Digital BW, The Print

Hi all

Does anyone have a 21 or 51 step wedge for LAB that they can send me?  

All the step wedges I have seen are grey gamma 2.2.

Thanks in advance

Steve

Steve Kale wrote:
> 
> Does anyone have a 21 or 51 step wedge for LAB that they can send me?  
> 
> All the step wedges I have seen are grey gamma 2.2.

Evidently I don't understand something, so I'll ask...

Why can't you just take one of the standard 21-step wedges and have PS 
convert it to Lab for you?

	Walt

http://www.hutchcolor.com/Targets%20&%20images%20to%20go/Lab%20Ramp_03.hqx

Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Kale"
<stevekale@b...> wrote:

> 
> Hi all
> 
> Does anyone have a 21 or 51 step wedge for LAB that they can send me?  
> 
> All the step wedges I have seen are grey gamma 2.2.
> 
> Thanks in advance
> 
> Steve

Because it converts the profile but the underlying pixel values don't change
- you still have L=54 at the 50% step for example (rather than L=50) - or am
I doing something wrong?  By a LAB step wedge I mean one where L steps down
from 100 to 0.

> From: Walt Farrell <wftemp1@...>
> 
> 
> Steve Kale wrote:
>> 
>> Does anyone have a 21 or 51 step wedge for LAB that they can send me?
>> 
>> All the step wedges I have seen are grey gamma 2.2.
> 
> Evidently I don't understand something, so I'll ask...
> 
> Why can't you just take one of the standard 21-step wedges and have PS
> convert it to Lab for you?
> 
> Walt
>

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Steve Kale" 
<stevekale@b...> wrote:
> 
> Hi all
> 
> Does anyone have a 21 or 51 step wedge for LAB that they can send me?  
> 
> All the step wedges I have seen are grey gamma 2.2.
> 
> Thanks in advance
> 
> Steve

Hi Steve,

Creating your own is pretty easy.  
I'd convert the the regular 21step into Lab first.  The values will be wrong
but you'll have all the labels and the layout.  Then redo the actual steps.
Start with a new gradient (dither off), then posterize part of it to 21steps.

This is an interesting exercise, you'll see the difference in curve shape with
the different gray spaces.  

Roy

Here's my 21 step wedge converted to LAB:
http://download.petraflux.com/stepwedge_lab.zip (21.3kb)

And my other stepwedges in case anyone needs them:
http://download.petraflux.com/technical.zip (2.35mb)

--
Daniel Staver
http://daniel.staver.no

thanks

> From: Daniel Staver <daniel@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Tue, 07 Dec 2004 18:56:45 +0100
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] LAB Step Wedge
> 
> 
> Here's my 21 step wedge converted to LAB:
> http://download.petraflux.com/stepwedge_lab.zip (21.3kb)
> 
> And my other stepwedges in case anyone needs them:
> http://download.petraflux.com/technical.zip (2.35mb)
> 
> --
> Daniel Staver
> http://daniel.staver.no
> 
> 
> 
> 
> 
> Please visit the Group Homepage to check the Files, and other resources as
> they are often being updated.
> 
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> 
> If you wish to receive no emails or just a daily digest, or you wish to
> unsubscribe, please edit your Membership preferences by visiting this same
> page.
> 
> Please follow these basic guidelines:
> - As threads develop, trim off excess portions of earlier messages to keep
> them short.
> - Good manners are required at all time. No personal attacks or flames.
> Hostile, aggressive or argumentative users may be removed from the membership
> without notice.
> - Keep your posts and threads related to the group topic of digital B&W
> printing. Users who persistently make off-topic posts may be removed from the
> membership.
> - By posting on this forum you agree to abide by the group rules and
> guidelines, and to abide by the actions and decisions of the group Owner and
> Moderators. See ³Group Topic, Rules and Guidelines² in the Files section:
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
> 
> BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT
> YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE ³OWNER² AND
> ³MODERATORS² OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU
> FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY
> DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS, GOODWILL,
> USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  ³OWNER² AND ³MODERATORS² OF
> DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
> DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW,
> THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF YOUR
> TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD PARTY ON THE
> DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER MATTER RELATING TO THE
> DIGITAL BW, THE PRINT YAHOO GROUP.
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
>

Well you don't need the step wedge to do that.  Just plot out the values.  I
did this when I started on this whole topic.  I also plotted the curve shape
of the QTR EEM space....even more interesting   ;-)

> 
> This is an interesting exercise, you'll see the difference in curve shape with
> the different gray spaces.
> 
> Roy
> 
> 
>

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:
> Well you don't need the step wedge to do that.  Just plot out the values.  I
> did this when I started on this whole topic.  I also plotted the curve shape
> of the QTR EEM space....even more interesting   ;-)
> 
> 
> 
> > 
> > This is an interesting exercise, you'll see the difference in curve shape with
> > the different gray spaces.
> > 
> > Roy
> > 
> > 
> >


Well after writing that Photoshop didn't have a Lab oriented gray space,
I figured why not??

So this is an close approximation:

http://www.harrington.com/LabGrayscale.zip

Just download it and extract.

Then in PS Color Settings for Gray -- Load Gray and load this profile.
Its called Lab Grayscale.icm

Assign this Profile to your 21step or image.
Its not quite perfect, the 95 step is only Lab 4 but all the other steps are right.
If this is useful I can probably make a perfect one later.


Roy

Roy

Ok now you are confusing me.  First of all, Load Gray won't let me select
the extracted file.  Secondly Daniel posted a 21 step wedge in LAB ie each
step represented a 5% change in L from 0 to 100 (Paul also sent me one
directly).  I can leave my grey space the same (gamma 2.2) and few the LAB
step wedge (colorsync manages this for me) and the eyedropper gives me the
right LAB readings.  It is the image file that needs the right LAB pixel
values.  

Steve

> From: Roy Harrington <roy@...>

> 
> Well after writing that Photoshop didn't have a Lab oriented gray space,
> I figured why not??
> 
> So this is an close approximation:
> 
> http://www.harrington.com/LabGrayscale.zip
> 
> Just download it and extract.
> 
> Then in PS Color Settings for Gray -- Load Gray and load this profile.
> Its called Lab Grayscale.icm
> 
> Assign this Profile to your 21step or image.
> Its not quite perfect, the 95 step is only Lab 4 but all the other steps are
> right.
> If this is useful I can probably make a perfect one later.
> 
> 
> Roy
>

Hi Steve,

Sorry about the confusion.  What Daniel posted was a wedge in Lab space, i.e.
a 3 channel file with L, a, and b channels.  

What I've got is a completely new color space (or maybe more accurately a new
Gray space).   It's a single channel that is just the L channel.  Since its a single 
channel it can be used with grayscale images.

The idea, inspired by you, is to use the same flavor of space thoughtout -- use
a Lab-like space as the editting space as well as the print space.

From the .zip file you should get a .icm file.  You can load this as the Working
Gray Space in Photoshop.  So in "Color Settings"  for Gray Space you can
Load this file and use it as your working space. Alternatively you can use it as a
proofing space.   You can also Assign the profile to your grayscale files -- they
will inherently display just as they print with QTR -- builtin proofing!

Roy


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:

> Roy
> 
> Ok now you are confusing me.  First of all, Load Gray won't let me select
> the extracted file.  Secondly Daniel posted a 21 step wedge in LAB ie each
> step represented a 5% change in L from 0 to 100 (Paul also sent me one
> directly).  I can leave my grey space the same (gamma 2.2) and few the LAB
> step wedge (colorsync manages this for me) and the eyedropper gives me the
> right LAB readings.  It is the image file that needs the right LAB pixel
> values.  
> 
> Steve
> 
> 
> > From: Roy Harrington <roy@h...>
> 
> > 
> > Well after writing that Photoshop didn't have a Lab oriented gray space,
> > I figured why not??
> > 
> > So this is an close approximation:
> > 
> > http://www.harrington.com/LabGrayscale.zip
> > 
> > Just download it and extract.
> > 
> > Then in PS Color Settings for Gray -- Load Gray and load this profile.
> > Its called Lab Grayscale.icm
> > 
> > Assign this Profile to your 21step or image.
> > Its not quite perfect, the 95 step is only Lab 4 but all the other steps are
> > right.
> > If this is useful I can probably make a perfect one later.
> > 
> > 
> > Roy
> >

PS won't recognize the .icm file and won't allow me to select it when I try
load it.... Maybe I should try downloading it again.

> From: Roy Harrington <roy@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 08 Dec 2004 00:47:24 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: LAB Step Wedge -- a grayscape Lab space
> 
> 
> 
> 
> Hi Steve,
> 
> Sorry about the confusion.  What Daniel posted was a wedge in Lab space, i.e.
> a 3 channel file with L, a, and b channels.
> 
> What I've got is a completely new color space (or maybe more accurately a new
> Gray space).   It's a single channel that is just the L channel.  Since its a
> single 
> channel it can be used with grayscale images.
> 
> The idea, inspired by you, is to use the same flavor of space thoughtout --
> use
> a Lab-like space as the editting space as well as the print space.
> 
> From the .zip file you should get a .icm file.  You can load this as the
> Working
> Gray Space in Photoshop.  So in "Color Settings"  for Gray Space you can
> Load this file and use it as your working space. Alternatively you can use it
> as a
> proofing space.   You can also Assign the profile to your grayscale files --
> they
> will inherently display just as they print with QTR -- builtin proofing!
> 
> Roy
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> 
> wrote:
>> Roy
>> 
>> Ok now you are confusing me.  First of all, Load Gray won't let me select
>> the extracted file.  Secondly Daniel posted a 21 step wedge in LAB ie each
>> step represented a 5% change in L from 0 to 100 (Paul also sent me one
>> directly).  I can leave my grey space the same (gamma 2.2) and few the LAB
>> step wedge (colorsync manages this for me) and the eyedropper gives me the
>> right LAB readings.  It is the image file that needs the right LAB pixel
>> values.  
>> 
>> Steve

Steve,

Put the icm file in your user>Library>Colorsync>Profiles folder.  I had 
no problem setting the gray space to this icm - it should appear in the 
PS Color Settings gray pop-up list with all of the other profile 
choices.

Carl

On Dec 8, 2004, at 8:59 AM, Steve Kale wrote:

>
> PS won't recognize the .icm file and won't allow me to select it when 
> I try
> load it.... Maybe I should try downloading it again.
>
>
>> From: Roy Harrington <roy@...>
>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Date: Wed, 08 Dec 2004 00:47:24 -0000
>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Subject: [Digital BW] Re: LAB Step Wedge -- a grayscape Lab space
>>
>>
>>
>>
>> Hi Steve,
>>
>> Sorry about the confusion.  What Daniel posted was a wedge in Lab 
>> space, i.e.
>> a 3 channel file with L, a, and b channels.
>>
>> What I've got is a completely new color space (or maybe more 
>> accurately a new
>> Gray space).   It's a single channel that is just the L channel.  
>> Since its a
>> single
>> channel it can be used with grayscale images.
>>
>> The idea, inspired by you, is to use the same flavor of space 
>> thoughtout --
>> use
>> a Lab-like space as the editting space as well as the print space.
>>
>> From the .zip file you should get a .icm file.  You can load this as 
>> the
>> Working
>> Gray Space in Photoshop.  So in "Color Settings"  for Gray Space you 
>> can
>> Load this file and use it as your working space. Alternatively you 
>> can use it
>> as a
>> proofing space.   You can also Assign the profile to your grayscale 
>> files --
>> they
>> will inherently display just as they print with QTR -- builtin 
>> proofing!
>>
>> Roy
>>
>>
>> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
>> <stevekale@b...>
>> wrote:
>>> Roy
>>>
>>> Ok now you are confusing me.  First of all, Load Gray won't let me 
>>> select
>>> the extracted file.  Secondly Daniel posted a 21 step wedge in LAB 
>>> ie each
>>> step represented a 5% change in L from 0 to 100 (Paul also sent me 
>>> one
>>> directly).  I can leave my grey space the same (gamma 2.2) and few 
>>> the LAB
>>> step wedge (colorsync manages this for me) and the eyedropper gives 
>>> me the
>>> right LAB readings.  It is the image file that needs the right LAB 
>>> pixel
>>> values.
>>>
>>> Steve
>
>
>
>
>
> Please visit the Group Homepage to check the Files, and other 
> resources as they are often being updated.
>
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
>
> If you wish to receive no emails or just a daily digest, or you wish 
> to unsubscribe, please edit your Membership preferences by visiting 
> this same page.
>
> Please follow these basic guidelines:
> - As threads develop, trim off excess portions of earlier messages to 
> keep them short.
> - Good manners are required at all time. No personal attacks or 
> flames. Hostile, aggressive or argumentative users may be removed from 
> the membership without notice.
> - Keep your posts and threads related to the group topic of digital 
> B&W printing. Users who persistently make off-topic posts may be 
> removed from the membership.
> - By posting on this forum you agree to abide by the group rules and 
> guidelines, and to abide by the actions and decisions of the group 
> Owner and Moderators. See „Group Topic, Rules and Guidelines‰ in the 
> Files section:
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
>
> BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE 
> PRINT YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE „OWNER‰ 
> AND „MODERATORS‰ OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE 
> LIABLE TO YOU FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
> CONSEQUENTIAL OR EXEMPLARY DAMAGES, INCLUDING BUT NOT LIMITED TO, 
> DAMAGES FOR LOSS OF PROFITS, GOODWILL, USE, DATA OR OTHER INTANGIBLE 
> LOSSES (EVEN IF THE  „OWNER‰ AND „MODERATORS‰ OF DIGITAL BW, THE PRINT 
> YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES), 
> RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW, 
> THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF 
> YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD 
> PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER 
> MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>

Ah sorry I made a stupid mistake.  I missed it on the list and was trying to
load it twice!

> From: Carl Schofield <scho@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Wed, 8 Dec 2004 09:11:53 -0500
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] Re: LAB Step Wedge -- a grayscape Lab space
> 
> 
> Steve,
> 
> Put the icm file in your user>Library>Colorsync>Profiles folder.  I had
> no problem setting the gray space to this icm - it should appear in the
> PS Color Settings gray pop-up list with all of the other profile
> choices.
> 
> Carl
> 
> On Dec 8, 2004, at 8:59 AM, Steve Kale wrote:
> 
>> 
>> PS won't recognize the .icm file and won't allow me to select it when
>> I try
>> load it.... Maybe I should try downloading it again.
>> 
>> 
>>> From: Roy Harrington <roy@...>
>>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>> Date: Wed, 08 Dec 2004 00:47:24 -0000
>>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>>> Subject: [Digital BW] Re: LAB Step Wedge -- a grayscape Lab space
>>> 
>>> 
>>> 
>>> 
>>> Hi Steve,
>>> 
>>> Sorry about the confusion.  What Daniel posted was a wedge in Lab
>>> space, i.e.
>>> a 3 channel file with L, a, and b channels.
>>> 
>>> What I've got is a completely new color space (or maybe more
>>> accurately a new
>>> Gray space).   It's a single channel that is just the L channel.
>>> Since its a
>>> single
>>> channel it can be used with grayscale images.
>>> 
>>> The idea, inspired by you, is to use the same flavor of space
>>> thoughtout --
>>> use
>>> a Lab-like space as the editting space as well as the print space.
>>> 
>>> From the .zip file you should get a .icm file.  You can load this as
>>> the
>>> Working
>>> Gray Space in Photoshop.  So in "Color Settings"  for Gray Space you
>>> can
>>> Load this file and use it as your working space. Alternatively you
>>> can use it
>>> as a
>>> proofing space.   You can also Assign the profile to your grayscale
>>> files --
>>> they
>>> will inherently display just as they print with QTR -- builtin
>>> proofing!
>>> 
>>> Roy
>>> 
>>> 
>>> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
>>> <stevekale@b...>
>>> wrote:
>>>> Roy
>>>> 
>>>> Ok now you are confusing me.  First of all, Load Gray won't let me
>>>> select
>>>> the extracted file.  Secondly Daniel posted a 21 step wedge in LAB
>>>> ie each
>>>> step represented a 5% change in L from 0 to 100 (Paul also sent me
>>>> one
>>>> directly).  I can leave my grey space the same (gamma 2.2) and few
>>>> the LAB
>>>> step wedge (colorsync manages this for me) and the eyedropper gives
>>>> me the
>>>> right LAB readings.  It is the image file that needs the right LAB
>>>> pixel
>>>> values.
>>>> 
>>>> Steve
>> 
>> 
>> 
>> 
>> 
>> Please visit the Group Homepage to check the Files, and other
>> resources as they are often being updated.
>> 
>> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
>> 
>> If you wish to receive no emails or just a daily digest, or you wish
>> to unsubscribe, please edit your Membership preferences by visiting
>> this same page.
>> 
>> Please follow these basic guidelines:
>> - As threads develop, trim off excess portions of earlier messages to
>> keep them short.
>> - Good manners are required at all time. No personal attacks or
>> flames. Hostile, aggressive or argumentative users may be removed from
>> the membership without notice.
>> - Keep your posts and threads related to the group topic of digital
>> B&W printing. Users who persistently make off-topic posts may be
>> removed from the membership.
>> - By posting on this forum you agree to abide by the group rules and
>> guidelines, and to abide by the actions and decisions of the group
>> Owner and Moderators. See „Group Topic, Rules and Guidelines‰ in the
>> Files section:
>> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
>> 
>> BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE
>> PRINT YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE „OWNER‰
>> AND „MODERATORS‰ OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE
>> LIABLE TO YOU FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
>> CONSEQUENTIAL OR EXEMPLARY DAMAGES, INCLUDING BUT NOT LIMITED TO,
>> DAMAGES FOR LOSS OF PROFITS, GOODWILL, USE, DATA OR OTHER INTANGIBLE
>> LOSSES (EVEN IF THE  „OWNER‰ AND „MODERATORS‰ OF DIGITAL BW, THE PRINT
>> YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES),
>> RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW,
>> THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF
>> YOUR TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD
>> PARTY ON THE DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER
>> MATTER RELATING TO THE DIGITAL BW, THE PRINT YAHOO GROUP.
>> 
>> Yahoo! Groups Links
>> 
>> 
>> 
>> 
>> 
>> 
>> 
> 
> 
> 
> 
> Please visit the Group Homepage to check the Files, and other resources as
> they are often being updated.
> 
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> 
> If you wish to receive no emails or just a daily digest, or you wish to
> unsubscribe, please edit your Membership preferences by visiting this same
> page.
> 
> Please follow these basic guidelines:
> - As threads develop, trim off excess portions of earlier messages to keep
> them short.
> - Good manners are required at all time. No personal attacks or flames.
> Hostile, aggressive or argumentative users may be removed from the membership
> without notice.
> - Keep your posts and threads related to the group topic of digital B&W
> printing. Users who persistently make off-topic posts may be removed from the
> membership.
> - By posting on this forum you agree to abide by the group rules and
> guidelines, and to abide by the actions and decisions of the group Owner and
> Moderators. See “Group Topic, Rules and Guidelines” in the Files section:
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint/files/
> 
> BY PARTICIPATING IN AND/OR POSTING MESSAGES TO THE DIGITAL BW, THE PRINT
> YAHOO! GROUP YOU EXPRESSLY UNDERSTAND AND AGREE THAT THE “OWNER” AND
> “MODERATORS” OF DIGITAL BW, THE PRINT YAHOO GROUP SHALL NOT BE LIABLE TO YOU
> FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL OR EXEMPLARY
> DAMAGES, INCLUDING BUT NOT LIMITED TO, DAMAGES FOR LOSS OF PROFITS, GOODWILL,
> USE, DATA OR OTHER INTANGIBLE LOSSES (EVEN IF THE  “OWNER” AND “MODERATORS” OF
> DIGITAL BW, THE PRINT YAHOO GROUP HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
> DAMAGES), RESULTING FROM: (i) THE USE OR THE INABILITY TO USE THE DIGITAL BW,
> THE PRINT YAHOO GROUP; (ii) UNAUTHORIZED ACCESS TO OR ALTERATION OF YOUR
> TRANSMISSIONS OR DATA; (iii) STATEMENTS OR CONDUCT OF ANY THIRD PARTY ON THE
> DIGITAL BW, THE PRINT YAHOO GROUP; OR (iv) ANY OTHER MATTER RELATING TO THE
> DIGITAL BW, THE PRINT YAHOO GROUP.
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
>

Hi Roy

Ok so I have it up now - well done, just the L channel - cool!  That saves
us a lot of storage space should we choose to work in LAB rather than Grey
Gamma 2.2 and like I had said before LAB is hard for colour but easy for
B&W.  

A couple of points:

1.  I suspect most of us will still start either with a Gray Gamma 2.2 file
(scanning B&W film) or an sRGB/Adobe RGB/scanner RGB file (shooting
digitally or scanning colour film).  Once this is in grey scale we should
CONVERT to LAB else all the tonal values will shift (where we had one shade
of grey will now become another and if we exposed a part of the image to
Kodak grey it will no longer be so).  Not a problem, of course, and better
than converting to LAB because at least with this Grey LAB we strip off the
a and b that aren't needed. Very very cool.

(I am very intrigued as to how you did this by the way.)

2.  Now that we have our image in LAB-lite we still have the issue of this
space not being the same as the printer space.  For starters, an image using
the full tonal range (such as an ordinary step wedge) has deeper blacks than
we can print and hence we don't have WYSIWYG.)  So no "built-in" proofing
:-(  See my last post to Keith in the other thread which I will reproduce
here:

"Even if the printer RIP automatically spaces LAB values from
dMin to dMax, ie 0 gets mapped to 16, 5 to 20 etc, you still end up with the
same result: the mid-point shifts.

(By the way, take a look at this sequence of co-ordinates, and their density
equivalents, and look how all print values are shifted.  Plot the step vs
density figures of the two papers and overlay LAB.  Even if the RIP doesn't
make this linear, as I believe was suggested, but curved in equal increments
of LAB, each paper has a different gamma and non have the same value or
curvature as LAB. Only as paper white moves closer to perfect white and ink
dMax approaches perfect black do the curves begin to converge and have the
same gamma.)"

Cheers

Steve

> From: Roy Harrington <roy@...>

> 
>  Alternatively you can use it
> as a
> proofing space.   You can also Assign the profile to your grayscale files --
> they
> will inherently display just as they print with QTR -- builtin proofing!
> 
> Roy
>

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:
> Hi Roy
> 
> Ok so I have it up now - well done, just the L channel - cool!  That saves
> us a lot of storage space should we choose to work in LAB rather than Grey
> Gamma 2.2 and like I had said before LAB is hard for colour but easy for
> B&W.  
> 
> A couple of points:
> 
> 1.  I suspect most of us will still start either with a Gray Gamma 2.2 file
> (scanning B&W film) or an sRGB/Adobe RGB/scanner RGB file (shooting
> digitally or scanning colour film).  Once this is in grey scale we should
> CONVERT to LAB else all the tonal values will shift (where we had one shade
> of grey will now become another and if we exposed a part of the image to
> Kodak grey it will no longer be so).  Not a problem, of course, and better
> than converting to LAB because at least with this Grey LAB we strip off the
> a and b that aren't needed. Very very cool.

The new space does several different things.   For printing through QTR
there is no effect.  Remember in the Print with Preview we select Same
as Source for the print.   We still have a grayscale image so this means 
the exact pixel values are sent to QTR.
For display though -- what you see on the screen -- there's still a bunch
of color management going on.  The pixels go from the gray space (now
just L) to Lab to the RGB of the monitor.  Before they went from gamma 2.2
to Lab to RGB.   So the new way we see the difference between 95 and 100
on the screen as well as on the print.

The bottom line is that you should Assign to the new space NOT Convert to it.

> 
> (I am very intrigued as to how you did this by the way.)

With mirrors of course.  Actually I tried a few things to find out what
was in the icc file for a gray space and then matched it to the known formulas.  
Now I have to go back and have it all calculated.

> 
> 2.  Now that we have our image in LAB-lite we still have the issue of this
> space not being the same as the printer space.  For starters, an image using
> the full tonal range (such as an ordinary step wedge) has deeper blacks than
> we can print and hence we don't have WYSIWYG.)  So no "built-in" proofing
> :-(  See my last post to Keith in the other thread which I will reproduce
> here:
> 
> "Even if the printer RIP automatically spaces LAB values from
> dMin to dMax, ie 0 gets mapped to 16, 5 to 20 etc, you still end up with the
> same result: the mid-point shifts.
> 
> (By the way, take a look at this sequence of co-ordinates, and their density
> equivalents, and look how all print values are shifted.  Plot the step vs
> density figures of the two papers and overlay LAB.  Even if the RIP doesn't
> make this linear, as I believe was suggested, but curved in equal increments
> of LAB, each paper has a different gamma and non have the same value or
> curvature as LAB. Only as paper white moves closer to perfect white and ink
> dMax approaches perfect black do the curves begin to converge and have the
> same gamma.)"

You are right that absolute values will vary based on dMin, dMax, the kind
of display you use, the lighting etc...  I lean toward the everything relative
point of view though.   With color management there are the different
renderings and Perceptual is usually the one of choice.   This corresponds to
the compressing the gamut mode.  The Absolute Colormetric is more like
your view but seems rarely used.

Roy

> 
> Cheers
> 
> Steve
> 
> > From: Roy Harrington <roy@h...>
> 
> > 
> >  Alternatively you can use it
> > as a
> > proofing space.   You can also Assign the profile to your grayscale files --
> > they
> > will inherently display just as they print with QTR -- builtin proofing!
> > 
> > Roy
> >

Roy, you might try printing a file in a different space and use your
new profile as the print space and see how it looks compared to the
monitor.
Just might work.
Personally I prefer working and editing in the space "linearized to"
for grayscale, less loss in the end I think.
But some people might find it useful if it works. Back when I was
testing QTR I made a custom gray space that visually matched it's
output on the monitor and printed to QTR through it, seemed to work fine.
Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Tyler Boley" <tyler@t...> 
wrote:
> 
> Roy, you might try printing a file in a different space and use your
> new profile as the print space and see how it looks compared to the
> monitor.
> Just might work.
> Personally I prefer working and editing in the space "linearized to"
> for grayscale, less loss in the end I think.

Exactly.  That's what I have now.   They are both Lab, L* based and
not only are they the same they match the human eye the best.

You may be getting the same effect using dot gain 20% for both.  I'm not
as sure about the math of dot gain though.  The dot gain 20% tells
you how the midpoint is affected -- 50+20 = 70 but I'm not sure how
you should calculate all the other points.

Roy

> But some people might find it useful if it works. Back when I was
> testing QTR I made a custom gray space that visually matched it's
> output on the monitor and printed to QTR through it, seemed to work fine.
> Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Roy Harrington"
<roy@h...> wrote:
...
> Exactly.  That's what I have now.   They are both Lab, L* based and
> not only are they the same they match the human eye the best.
> 
> You may be getting the same effect using dot gain 20% for both.  I'm not
> as sure about the math of dot gain though.  The dot gain 20% tells
> you how the midpoint is affected -- 50+20 = 70 but I'm not sure how
> you should calculate all the other points.

I think it's a technical misnomer in StudioPrint. Dot gain is a
measured physical result, as you mentioned. So in StudioPrint, it has
to be a simulation, and it has to be a "simple" dot gain. That is, mid
point moves by the spec, other points move in some fashion apparently
agreed upon by those wiser than I. You see the same effect in
Photoshop my using only the mid point. I have not seen a spec for how
the rest of that works. But "simple" dot gain (mid point only) seems
to be a convention out there.
I suppose I could measure the actual output then derive and enter a
more complex curve, but this seems to be working and damn, there's
work to do.
I think, for our purposes, gamma would have been a better user
selectable descriptor. Not sure why they picked that, could be for
simulated proofing etc..
I could use 0% dot gain, but I think it'd be a pretty bad editing
space, and considerable loss when having to convert incoming files to
it. I think in the newest version, the target is more user definable,
haven't tried it yet.
I agree LAB is a good choice if you have to pick one.
Tyler

Hi Roy


> From: Roy Harrington <roy@...>


 
> The new space does several different things.   For printing through QTR
> there is no effect.  Remember in the Print with Preview we select Same
> as Source for the print.   We still have a grayscale image so this means
> the exact pixel values are sent to QTR.

Yes and there is no colour management in the RIP.

> For display though -- what you see on the screen -- there's still a bunch
> of color management going on.  The pixels go from the gray space (now
> just L) to Lab to the RGB of the monitor.  Before they went from gamma 2.2
> to Lab to RGB.   

Yes

>So the new way we see the difference between 95 and 100
> on the screen as well as on the print.
> 
> The bottom line is that you should Assign to the new space NOT Convert to it.
> 

I am still not convinced of this but let me think about it.  I agree that
the file that gets sent to QTR (via Same as Source) needs to be LAB or
LAB-grey.  But if I took a photograph such that a portion of the subject is
Kodak middle grey (L=50) and this successfully makes it through to my B&W
image on screen (ie is still L=50) before going to LAB-grey, if I ASSIGN
LAB-grey the L value of this portion of the image will change.

(As an example, pull up a grey gamma 2.2 step wedge.  The 50% step is L=54.
Assign LAB-Grey and the 50% step changes colour and becomes L=50.  What was
L=50 also moves to something less than that.  My image has changed and I
have lost my reference point that I noted at the time of exposure.)


>> 
>> (I am very intrigued as to how you did this by the way.)
> 
> With mirrors of course.  Actually I tried a few things to find out what
> was in the icc file for a gray space and then matched it to the known
> formulas.  
> Now I have to go back and have it all calculated.
> 

You are a genius.

>> 
>> 2.  Now that we have our image in LAB-lite we still have the issue of this
>> space not being the same as the printer space.  For starters, an image using
>> the full tonal range (such as an ordinary step wedge) has deeper blacks than
>> we can print and hence we don't have WYSIWYG.)  So no "built-in" proofing
>> :-(  See my last post to Keith in the other thread which I will reproduce
>> here:
>> 
>> "Even if the printer RIP automatically spaces LAB values from
>> dMin to dMax, ie 0 gets mapped to 16, 5 to 20 etc, you still end up with the
>> same result: the mid-point shifts.
>> 
>> (By the way, take a look at this sequence of co-ordinates, and their density
>> equivalents, and look how all print values are shifted.  Plot the step vs
>> density figures of the two papers and overlay LAB.  Even if the RIP doesn't
>> make this linear, as I believe was suggested, but curved in equal increments
>> of LAB, each paper has a different gamma and non have the same value or
>> curvature as LAB. Only as paper white moves closer to perfect white and ink
>> dMax approaches perfect black do the curves begin to converge and have the
>> same gamma.)"
> 
> You are right that absolute values will vary based on dMin, dMax, the kind
> of display you use, the lighting etc...  I lean toward the everything relative
> point of view though.   With color management there are the different
> renderings and Perceptual is usually the one of choice.   This corresponds to
> the compressing the gamut mode.  The Absolute Colormetric is more like
> your view but seems rarely used.
> 

Not quite.  In my methodology there has been no "compression of gamut" per
se at the point of "calibrating" the printer - merely a recognition of what
the range is.  This is important.  I make no judgement call at this point as
to how out-of-gamut values should be treated.  I recognise that the printer
can print a good portion of the LAB-grey space and I simply require that it
do so for the portion it can and I note down the portion that it can't.

With the recognition that the printer can only render say that portion of
the LAB-grey space defined by 16<=L=>96, I then look at my image.  How the
image is then compressed with a simple curve to 16<=L=>96 has an infinite
number of possibilities - all of which I control simply with one neat PS
curve.  It is actually better than colorsync in that you have an infinite
number of possible curves rather than 4 options.  For example, if I chose to
clip certain values I am in effect using a mix of Absolute Colormetric and
Perceptual.

OK you could say that I make the call at the time of calibration that IF I
don't do anything else, out-of-gamut values will be clipped to dMax or dMin
respectively!  But you gotta take the package in the same way I must take
the current package of a transformation function embedded in the RIP and the
transformation function I must manually do during soft proofing to get the
image to "look right" again.  If I do nothing with the current setup I don't
get a satisfactory image - I have to go back and rejigger it with a
softproof in hand.  Worse yet, if my image is fully in gamut (eg my
photography class example) at the moment I still have to go back and
rejigger it to get the image right.

Cheers

Steve

> 
> >So the new way we see the difference between 95 and 100
> > on the screen as well as on the print.
> > 
> > The bottom line is that you should Assign to the new space NOT Convert to it.
> > 
> 
> I am still not convinced of this but let me think about it.  I agree that
> the file that gets sent to QTR (via Same as Source) needs to be LAB or
> LAB-grey.  But if I took a photograph such that a portion of the subject is
> Kodak middle grey (L=50) and this successfully makes it through to my B&W
> image on screen (ie is still L=50) before going to LAB-grey, if I ASSIGN
> LAB-grey the L value of this portion of the image will change.
> 
> (As an example, pull up a grey gamma 2.2 step wedge.  The 50% step is L=54.
> Assign LAB-Grey and the 50% step changes colour and becomes L=50.  What was
> L=50 also moves to something less than that.  My image has changed and I
> have lost my reference point that I noted at the time of exposure.)
> 

This is exactly as is should be.  If you have a gg2.2 50% step, it reads K=50 and
the internal pixel value is 127 = 255*.50  if you look at the Info and see L=54
what you are seeing is a CONVERSION of  50 gg2.2 to Lab and the value comes
out 54.  If you were to convert-to-profile the file the pixel value would change from
127 to about 138 = 255*.54.   However if you assign-profile the pixel value
stays at 127 and now when you see the Info L=50 because thats the pixel value.

When you Assign the actual pixel numbers don't change, just the meaning of the
numbers.  Convert changes the pixel numbers so that the new number with the
new meaning is the same gray value as the old number with the old meaning.

If you've already got a file that prints well before you don't want to change all the
pixel numbers because then your print will change.  We're changing just the meanings
so that the display gives a better match to the print.

Of course if you are coming from the other side and like your image on the monitor 
but not the print.  Converting may get the print closer to the monitor.


> > 
> > You are right that absolute values will vary based on dMin, dMax, the kind
> > of display you use, the lighting etc...  I lean toward the everything relative
> > point of view though.   With color management there are the different
> > renderings and Perceptual is usually the one of choice.   This corresponds to
> > the compressing the gamut mode.  The Absolute Colormetric is more like
> > your view but seems rarely used.
> > 
> 
> Not quite.  In my methodology there has been no "compression of gamut" per
> se at the point of "calibrating" the printer - merely a recognition of what
> the range is.  This is important.  I make no judgement call at this point as
> to how out-of-gamut values should be treated.  I recognise that the printer
> can print a good portion of the LAB-grey space and I simply require that it
> do so for the portion it can and I note down the portion that it can't.
> 
> With the recognition that the printer can only render say that portion of
> the LAB-grey space defined by 16<=L=>96, I then look at my image.  How the
> image is then compressed with a simple curve to 16<=L=>96 has an infinite
> number of possibilities - all of which I control simply with one neat PS
> curve.  It is actually better than colorsync in that you have an infinite
> number of possible curves rather than 4 options.  For example, if I chose to
> clip certain values I am in effect using a mix of Absolute Colormetric and
> Perceptual.
> 
> OK you could say that I make the call at the time of calibration that IF I
> don't do anything else, out-of-gamut values will be clipped to dMax or dMin
> respectively!  But you gotta take the package in the same way I must take
> the current package of a transformation function embedded in the RIP and the
> transformation function I must manually do during soft proofing to get the
> image to "look right" again.  If I do nothing with the current setup I don't
> get a satisfactory image - I have to go back and rejigger it with a
> softproof in hand.  Worse yet, if my image is fully in gamut (eg my
> photography class example) at the moment I still have to go back and
> rejigger it to get the image right.

I get what you are saying, I just don't think its as desireable.  I think the
relationship between values is much more important to overall effect rather
than the absolute densities.  I think with your scheme you'd always have this
extra step of trying to find and match up your dmin and dmax.

Roy

> 
> Cheers
> 
> Steve

> From: Roy Harrington <roy@...>

> 
> I get what you are saying, I just don't think its as desireable.  I think the
> relationship between values is much more important to overall effect rather
> than the absolute densities.  I think with your scheme you'd always have this
> extra step of trying to find and match up your dmin and dmax.
> 


Hi Roy et al

I believe in the relationship between variables also.  I also believe in the
LAB mantra and would like the relationship between variables to meet LAB
specs because you have sold me on the fact that it is the way the eye sees.

In my scheme, I don't have to find dMin and dMax - they are known as they
are in the current methodology.  "Matching them up" takes about 3 seconds.
With the current methodology, I have to "match up" the end points and all
points in between.  I could get what currently has to be done in with a soft
proof, a visual and imprecise realignment of two images on screen, in this
same 3 seconds.  Furthermore if my image is all in-gamut such as my simple
classroom example, I don't even have to do that.

The reason why the current method has to fall back on to soft proofing is
very very simple.  This is very important and is the crux of this
conversation.  (Anyone want any more "verys"?)  While the current process of
"linearization" involves linearization OF LAB values it does not linearize
TO LAB (over the dynamic range of the printer).  This has a number of big
ramifications: our workspace (even with LAB-Grey!) will never match the
print space and the gamma of our print space is different for different
papers meaning even those parts of the density spectrum BOTH papers are
currently capable of rendering will be rendered differently.  This is why a
value such as L=50 in the image will never print at L=50 nor even
consistently across various papers. (This would not be a big deal if we had
colorsync to manage the transition between these (linear) spaces but we
don't.)  As a result, we have to soft proof even to get an in gamut image to
print properly.

I admit I am asking you to do things differently.  Specifically I am asking
you to:

1.  Calibrate the RIP differently (TO lab, not OF Lab)
2.  This means you will need to look at step wedges a little differently
3.  Draw the curves that manage tonal compression (or currently fix the
RIP's tonal compression) differently

Actually a lot of people (most?) don't even worry about RIP calibration and
step wedges.  They simply rely on the work of others (I have no problem with
this) and so, for many, items 1 and 2 above are a non-issues.  With regard
to item 3, we who calibrate the RIP could simply distribute our "standard"
curves for each paper, much in the same way Paul Roark does. In this case
the workflow for most collapses even further.

This is change, yes.  But I believe it will result in a simpler, faster,
more visually intuitive and more precise workflow than the current.

Another very important point.  There is nothing in my proposed workflow that
results in or calls for "clipping".  The image file is not clipped.  The
gamut is not clipped.  You CAN clip if you so choose but this is your call.

(Note a wetroom photographer clips when he let's the non V zones fall where
they may and they fall outside the tonal range of the paper.  The only way
he can manage this is through dodging and burning.  We have dodging and
burning AND curves.)

Guys, I can't go on with this in this form.  If I could show you what I mean
with the aid of a few simple diagrams we would at least reach comprehension
(if not adoption!) much faster.  So why don't I do this.  I will write up
with the help of a few diagrams what I am saying and proposing.  I will give
it three simple headings:

1.  Steve's RIP Calibration (avoiding the word linearization!)
2.  Managing compression of the image file to printer tonal range
3.  Workflow summary

I'll try to note what I see are the key issues with the current system and
why these are overcome with my proposed method.  I'll send it to you by
email offline and you can either read it at your leisure or toss it in the
trash.  How's that?

Steve

On Wednesday, Dec 8, 2004, at 15:13 US/Pacific, 
DigitalBlackandWhiteThePrint@yahoogroups.com wrote:

> Message: 13
>    Date: Wed, 08 Dec 2004 21:12:25 -0000
>    From: "Roy Harrington" <roy@...>
> Subject: Re: LAB Step Wedge -- a grayscape Lab space
>
>
>>
>
> The new space does several different things.   For printing through QTR
> there is no effect.  Remember in the Print with Preview we select Same
> as Source for the print.   We still have a grayscale image so this 
> means
> the exact pixel values are sent to QTR.
> For display though -- what you see on the screen -- there's still a 
> bunch
> of color management going on.  The pixels go from the gray space (now
> just L) to Lab to the RGB of the monitor.  Before they went from gamma 
> 2.2
> to Lab to RGB.   So the new way we see the difference between 95 and 
> 100
> on the screen as well as on the print.
>
> The bottom line is that you should Assign to the new space NOT Convert 
> to it.

Are you sure Roy? Sure the data stays the same, but our view of it 
changes (especially in the darkest tones) and we edit the image 
differently to compensate for the new LAB working space.

What I don't understand, is that if I have a QTR curve that works for 
gamma 2.2 space, then I would need to create a new curve for a LAB 
working space. If I create such a new QTR curve that works for LAB 
space and not gamma 2.2 then I would want to "convert to profile" when 
changing from gamma 2.2 image to a LAB greyspace image.

If I don't create a new QTR curve, then I loose my visual screen to 
print match, even if I can make the the original print while working 
from LAB space. It's hard to write this stuff and have it make sense! 
But it makes perfect sense to me <g>
>
> You are right that absolute values will vary based on dMin, dMax, the 
> kind
> of display you use, the lighting etc...  I lean toward the everything 
> relative
> point of view though.   With color management there are the different
> renderings and Perceptual is usually the one of choice.   This 
> corresponds to
> the compressing the gamut mode.  The Absolute Colormetric is more like
> your view but seems rarely used.

Absolute colormetric  is used when proofing a low gamut output on a 
high gamut output device. (like what would newsprint look like printed 
on my epson 1280?) Isn't it also used in softproof profiles or 
conversions?

-bruce
>
> Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, bruce greene 
<bagreene@v...> wrote:
> 
> On Wednesday, Dec 8, 2004, at 15:13 US/Pacific, 
> DigitalBlackandWhiteThePrint@yahoogroups.com wrote:
> 
> > Message: 13
> >    Date: Wed, 08 Dec 2004 21:12:25 -0000
> >    From: "Roy Harrington" <roy@h...>
> > Subject: Re: LAB Step Wedge -- a grayscape Lab space
> >
> >
> >>
> >
> > The new space does several different things.   For printing through QTR
> > there is no effect.  Remember in the Print with Preview we select Same
> > as Source for the print.   We still have a grayscale image so this 
> > means
> > the exact pixel values are sent to QTR.
> > For display though -- what you see on the screen -- there's still a 
> > bunch
> > of color management going on.  The pixels go from the gray space (now
> > just L) to Lab to the RGB of the monitor.  Before they went from gamma 
> > 2.2
> > to Lab to RGB.   So the new way we see the difference between 95 and 
> > 100
> > on the screen as well as on the print.
> >
> > The bottom line is that you should Assign to the new space NOT Convert 
> > to it.
> 
> Are you sure Roy? Sure the data stays the same, but our view of it 
> changes (especially in the darkest tones) and we edit the image 
> differently to compensate for the new LAB working space.
> 
> What I don't understand, is that if I have a QTR curve that works for 
> gamma 2.2 space, then I would need to create a new curve for a LAB 
> working space. If I create such a new QTR curve that works for LAB 
> space and not gamma 2.2 then I would want to "convert to profile" when 
> changing from gamma 2.2 image to a LAB greyspace image.
> 
> If I don't create a new QTR curve, then I loose my visual screen to 
> print match, even if I can make the the original print while working 
> from LAB space. It's hard to write this stuff and have it make sense! 
> But it makes perfect sense to me <g>

I'd first like to say that the best thing to do is try things out and see.

But here is my reasoning.   The QTR curves/profiles aren't based on the
photoshop gray space at all.  When you print and select "Same As Source"
you are just passing the data through without modification.  QTR gets
the raw data.  When you did all the linearization it was based on raw
pixel data -- it was not at all dependent on the gray space.  So the
existing QTR profiles should work just fine as long as the pixel values
don't change, hence Assign-Profile.   Another way to look at it is: do
I want to preserve the way the screen looks (use Convert) or the way the
print looks (use Assign).

So, we are we doing all this??

In the past, (without using softproof) the display and the print never looked
the same.  My idea with the new gray space is to bring those two different
looks closer together -- naturally at least one of them has to change.
It's kind of like a "for free, builtin, generic" softproof.  

> >
> > You are right that absolute values will vary based on dMin, dMax, the 
> > kind
> > of display you use, the lighting etc...  I lean toward the everything 
> > relative
> > point of view though.   With color management there are the different
> > renderings and Perceptual is usually the one of choice.   This 
> > corresponds to
> > the compressing the gamut mode.  The Absolute Colormetric is more like
> > your view but seems rarely used.
> 
> Absolute colormetric  is used when proofing a low gamut output on a 
> high gamut output device. (like what would newsprint look like printed 
> on my epson 1280?) Isn't it also used in softproof profiles or 
> conversions?

I don't know what really goes on inside, but that sounds plausible.  But I
don't think we "need" absolute in the QTR printing process.

Roy

> 
> -bruce
> >
> > Roy

> From: Roy Harrington <roy@...>



>> Are you sure Roy? Sure the data stays the same, but our view of it
>> changes (especially in the darkest tones) and we edit the image
>> differently to compensate for the new LAB working space.
>> 
>> What I don't understand, is that if I have a QTR curve that works for
>> gamma 2.2 space, then I would need to create a new curve for a LAB
>> working space. If I create such a new QTR curve that works for LAB
>> space and not gamma 2.2 then I would want to "convert to profile" when
>> changing from gamma 2.2 image to a LAB greyspace image.
>> 
>> If I don't create a new QTR curve, then I loose my visual screen to
>> print match, even if I can make the the original print while working
>> from LAB space. It's hard to write this stuff and have it make sense!
>> But it makes perfect sense to me <g>
> 
> I'd first like to say that the best thing to do is try things out and see.
> 
> But here is my reasoning.   The QTR curves/profiles aren't based on the
> photoshop gray space at all.  When you print and select "Same As Source"
> you are just passing the data through without modification.  QTR gets
> the raw data.  When you did all the linearization it was based on raw
> pixel data -- it was not at all dependent on the gray space.

Yes this is correct.  We measure the density printed for a the image file's
"raw data" and then feed this back into the equation via LINEARIZE=

>So the
> existing QTR profiles should work just fine as long as the pixel values
> don't change, hence Assign-Profile.

This would work if the print space was LAB but it isn't.

>Another way to look at it is: do
> I want to preserve the way the screen looks (use Convert) or the way the
> print looks (use Assign).
> 

This is correct.  But for most people, what they have on screen is what they
want to print and hence convert is the right answer.

Bruce,

Unless I am mistaken, and I am happy to be proven incorrect, when we tag a
file initially with a profile, eg Gray Gamma 2.2, we are giving reference to
the individual pixel values.  So when the file has a pixel with value, in 8
bit, of 128 it can be described as 128/Gray Gamma 2.2. 128/Gray Gamma 2.2
has a density of 0.66.  If our screen's profile were LAB - which of course
it isn't as it has its own profile! but just for illustrative purposes -
colorsync would take that 128/Gray Gamma 2.2 pixel and deliver the screen
not 128 but 138.  This is because 138 is L=54 (there is some rounding here)
or the grey we want to see.

Now let's send the image file pixel value to a printer calibrated such that
it matched LAB.  We send the raw pixel values as noted above. In our
example, let's look at 3 scenarios.  Firstly let's send the Gray Gamma file.
The printer gets sent value 128 and prints density of 0.73 (ie the density
equivalent of 128/256x100=50).  If we Assign LAB to the gray gamma 2.2 image
there is no translation of raw pixel values.  Instead the existing raw pixel
values take on their new meaning in the new space.  This is why when you
assign a profile its look changes on screen. The printer still gets 128 and
prints the same density but this time it matches the screen because the
image on screen has changed.   Now the last scenario.  We Convert and all
pixels with value 128 now have file values of 138, ie the pixel vales have
been remapped to their correct respective places in the new space.  The
printer prints L=54 and we get the grey we wanted.

Cheers

Steve

Steve,

I see from your  post that we are working with different QTR curves, 
hence my profile assign/convert approach is different.

I've made my QTR curves by eye, without measurement, to match gamma 2.2 
working space because I  don't have a densitometer to measure the 
output. So I have not used the QTR linearize function. Believe it  or 
not, I've been quite successful at creating these curves (there was a 
bit of learning by  trial and error  involved but I've got  it down 
pretty good now).

So am I correct now in assuming that the Linearize function in QTR 
linearizes to LAB values? If so the LAB grey space makes perfect sense 
to match the Linearized output. I assume that the Linearized QTR/LAB 
output is not an exact density match to the monitor, but the perceptual 
change of densities in a printed step wedge matches the perceptual 
change of the step wedge in LAB/grey working space.  A "perceptual" 
working space conversion if you will.

So far, so good. My question: How does this approach deal with the 
reduced density range of a print vs. the monitor w/o softproofing by 
measured output?

IOW, I suspect that one still needs the softproof in addition to the 
LAB/grey space and Linearized output curve for true WYSIWYG printing. 
Still the LABgrey space combined with the LAB based Linearization seems 
to be a great starting point to standardizing the printer behavior. So 
now I'll have to find a densitometer?

Cheers,
-bruce


On Friday, Dec 10, 2004, at 08:53 US/Pacific, 
DigitalBlackandWhiteThePrint@yahoogroups.com wrote:

> Message: 8
>    Date: Fri, 10 Dec 2004 12:59:11 +0000
>    From: Steve Kale <stevekale@...>
> Subject: Re: Re: LAB Step Wedge -- a grayscape Lab space
>
>
>
>> I'd first like to say that the best thing to do is try things out and 
>> see.
>>
>> But here is my reasoning.   The QTR curves/profiles aren't based on 
>> the
>> photoshop gray space at all.  When you print and select "Same As 
>> Source"
>> you are just passing the data through without modification.  QTR gets
>> the raw data.  When you did all the linearization it was based on raw
>> pixel data -- it was not at all dependent on the gray space.
>
> Yes this is correct.  We measure the density printed for a the image 
> file's
> "raw data" and then feed this back into the equation via LINEARIZE=
>
>> So the
>> existing QTR profiles should work just fine as long as the pixel 
>> values
>> don't change, hence Assign-Profile.
>
> This would work if the print space was LAB but it isn't.
>
> Cheers
>
> Steve

> From: bruce greene <bagreene@...>

 
> So am I correct now in assuming that the Linearize function in QTR
> linearizes to LAB values?

Bruce I had to laugh when I read this. This thread started as a spur from a
thread titled "Tonal range and linearization".  Your question is in essence
the topic of that thread.  QTR "linearizes LAB values".  Whether that means
linearizes to LAB is a whole different kettle of fish!!


> So far, so good. My question: How does this approach deal with the
> reduced density range of a print vs. the monitor w/o softproofing by
> measured output?
> IOW, I suspect that one still needs the softproof in addition to the
> LAB/grey space and Linearized output curve for true WYSIWYG printing.
> Still the LABgrey space combined with the LAB based Linearization seems
> to be a great starting point to standardizing the printer behavior. So
> now I'll have to find a densitometer?

Read the other thread.... And then come back.

;-)

Bruce

I am sorry.  I shouldn't have blown you off so fast.  I also should have added a better 
explanation when I curtly replied to Roy's post by saying:

>So the
> existing QTR profiles should work just fine as long as the pixel values
> don't change, hence Assign-Profile.

This would work if the print space was LAB but it isn't.



Here is a fuller explanation and also, in effect, a summary of the other thread.  To explain 
things more easily, go to this page and download the one page pdf file:

http://homepage.mac.com/stevekale/stevekale2/FileSharing37.html

It saves me having to put a bunch of numbers in this post and also allows you to look at a 
couple of charts which will help.

A RIP like QTR is, in effect, a set of look up tables which tell the printer how much of each 
ink to put down for each possible image file pixel value.  Add the amounts of each ink 
together and you get total ink, and total ink determines the density printed.  QTR works in 
8 bit like many (most?) other printer drivers - although all computations are done in 16 bit 
- and so the possible range of image file values is 0-255.  Roy will correct me if I am 
wrong here but the final part of the calibration process for QTR is a "linearize" function.  
What this function does is to make sure that there is a nice linear progression in LAB's L 
value from dMin to dMax.  Note I said a progression in L and not density.  The density 
curve is not straight but L is.  This reflects the way the eye sees.  (In LAB space L goes 
from 0 (pixel value 0) to 100 (pixel value 255, 8 bit) in a straight line.)

Now look at the table in the pdf sheet.  There are 3 "input" columns.  These just show 
possible input values in 21 (5%) steps:  firstly 8 bit, then LAB and lastly % black.  The next 
column has the densities that the LAB space prescribes for each step of input.  The 
formula to get these figures has been tossed up a couple of times in recent posts so I 
won't repeat it here.  The first I whited out because it is really infinity and I had to plug a 
number to make the chart below the table print sensibly.

Now the output.  3 columns each for two paper types: first EEM and, secondly, a 
hypothetical glossy or semi-gloss paper.  For each paper there is L, density, and the 8 bit 
equivalent of the L figure.  For now just worry about the first two columns for each.

As I said above, I understand QTR is calibrated to get a smooth, straight line progression 
in LAB values from dMax at step 100 to dMin at step 0.  (Note all the figures you see are 
the derived by computing forecast values - I am sure there is some variance in 
implementation.  I used forecast values to avoid this variance clouding the concepts and 
because you can do this exercise without having to buy a densimeter!)   So if we look at 
EEM which with Eboni produces a dMax of around 1.68 and has a paper white or dMin of 
0.04, the progression in L is from 16 (the L value which gives a density of 1.68) to 96 (the 
L value which gives a density of 0.04) in equal steps of 4 L.  The densities associated with 
each step are in the column next to them.  Same process for the hypothetical glossy 
paper.

The chart immediately below the table plots these densities for each input step.  I have 
also overlaid a curve of the reference LAB densities for the same input values.  Remember 
we are using a Same as Source workflow and so the RIP is fed the raw pixel values from the 
file.  For each paper you can read off what density is printed for each pixel value input.  
You can also compare them to LAB.

To clarify my rebuttal to Roy, you can see how the print space for EEM, for example, is not 
the same as LAB (nor could it be - we can't print perfect black, nothing can!).  Almost all 
file pixel values will be rendered lighter than desired.  So even if you have your image on 
screen in LAB (or LAB-grey) and it looks just the way you'd like, it is not going to print like 
that.  

(One other thing to remember.  When you look at the file on screen you aren't looking at 
perfect LAB either - your display can't produce a perfect black!  You are looking at 
colorsync's rendition of the LAB file in your monitor space done according to whether you 
selected Relative Colormetric etc.  Because we print with Same as Source we don't have 
colorsync's help with managing the different shape of the workspace, LAB, to the print 
space as described in the chart.)  

Now for the remaining two columns in the table and the two screen grabs from Photoshop 
at the bottom of the page.  Look at the EEM 8 Bit Equiv column.  All this does is convert 
the EEM L value to its place in the 0-255 8 bit scale.  So 16 becomes 16/100 x 255 = 41.  
In 8 bit LAB space, the value 41 equates to LAB 16 which in turn has a density of 1.68.  
And so on for the other numbers (and the other paper).  Now you can get a sense for the 
"effective" pixel value remapping that the RIP is doing.  I say effective because the file 
values are not changed but you can see that an 8 bit value of 0 is printed at density 1.68 
which is actually  the density that would otherwise be associated with a pixel value of 41 in 
LAB space etc etc.

You can simulate this pixel transformation in Photoshop using the Curves function.  Bring 
up a 21 step wedge (or any other file), make sure it is tagged as LAB (either by converting 
or assigning it doesn't matter for this exercise) and look at it.  Now do a curves layer and 
input the co-ordinates that are listed for EEM - 8 bit input to 8 bit equiv output.  You can 
actually cut to the chase and do just the beginning and end - it is a straight line in the 
middle.  The two screen grabs at the bottom of the page show the "curves" for each paper.  
NOW, with Preview checked you can see how your image will be printed with QTR.  (Just 
don't print it with the curve in place else you will double the transformation!)

Remember this "curve" is buried in the RIP - you can't edit it.  It is also different for each 
paper.  It is also a straight line.  This, coupled with the general shift up in all values and 
hence lightening of most input values (look at the shift in all the midtones), is why we have 
to go back to our image with a soft proof methodology and reinstitute some rebalancing 
or curvature into the transformation.  Typically this is done with an "s curve" over the full 
range of image values (because all are sent to the printer as is).  After doing that, the total 
transformation at work is, obviously, the summation of the RIP curve (depicted in the 
screen grabs) and whatever s curve you applied.

Now for the debate on the other thread.  In essence, I have been arguing that we are better 
off doing the remapping with a curves layer in Photoshop and thereby transforming actual 
pixel values sent to the printer rather than doing the transformation in the RIP.  Why?  Two 
principal reasons:  

Firstly, by doing it in PS we can more easily round out the curve in a manner that balances 
the relative tones in a way that respects the image and our artistic eye - we might ensure 
for example that the mid point  and a bunch of the mid tone range is not moved, thereby 
leaving the coompression in tonal range more concentrated in the shadows and highlights.  
We can achieve the same end result with the current setup and two curves, an S curve and 
the embedded RIP curve, but it is not as easy to see what is really going on and the curve 
that you can edit is only half the story so-to-speak. 

Secondly, and this finally answers your soft proof question, we get to use Photoshop's 
built in Preview. When we have a transformation which alters pixel values the effect is 
rendered on screen for us to see.  Thus by having all of the remapping done to the image 
file (temporarily as a separate layer for printing only!!) in a layer we can see the results of 
our work - real time soft proofing!  

So in my proposed methodology, I would in essence edit the image to my liking on a well-
calibrated monitor (this is reason enough to own a photospectrometer) in a workspace 
that matches my print space.  Apply the "print curve" and check my on-screen perfect 
preview of the image (except for ink hue) and maybe tweak the curve for the specifics of 
the paper/ink tonal compression effects on this image, and then print.  I would make sure 
that the "print curve" is saved as a layer because if I then decide to print to glossy paper I 
don't need to compress the tonal range so much and hence I can use a broader curve.

I hope this helps 

Steve



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale <stevekale@b...> 
wrote:

> 
> 
> 
> > From: bruce greene <bagreene@v...>
> 
>  
> > So am I correct now in assuming that the Linearize function in QTR
> > linearizes to LAB values?
> 
> Bruce I had to laugh when I read this. This thread started as a spur from a
> thread titled "Tonal range and linearization".  Your question is in essence
> the topic of that thread.  QTR "linearizes LAB values".  Whether that means
> linearizes to LAB is a whole different kettle of fish!!
> 
> 
> > So far, so good. My question: How does this approach deal with the
> > reduced density range of a print vs. the monitor w/o softproofing by
> > measured output?
> > IOW, I suspect that one still needs the softproof in addition to the
> > LAB/grey space and Linearized output curve for true WYSIWYG printing.
> > Still the LABgrey space combined with the LAB based Linearization seems
> > to be a great starting point to standardizing the printer behavior. So
> > now I'll have to find a densitometer?
> 
> Read the other thread.... And then come back.
> 
> ;-)

On Saturday, Dec 11, 2004, at 17:38 US/Pacific, 
DigitalBlackandWhiteThePrint@yahoogroups.com wrote:

> Message: 7
>    Date: Sat, 11 Dec 2004 12:52:49 -0000
>    From: "Steve Kale" <stevekale@...>
> Subject: Re: Re: LAB Step Wedge -- a grayscape Lab space
>
>
> Bruce
>
> I am sorry.  I shouldn't have blown you off so fast.  I also should 
> have added a better
> explanation when I curtly replied to Roy's post by saying:
>
>> So the
>> existing QTR profiles should work just fine as long as the pixel 
>> values
>> don't change, hence Assign-Profile.
>
> This would work if the print space was LAB but it isn't.
>
>
>
> Here is a fuller explanation and also, in effect, a summary of the 
> other thread.  To explain
> things more easily, go to this page and download the one page pdf file:
>
> http://homepage.mac.com/stevekale/stevekale2/FileSharing37.html
>
> It saves me having to put a bunch of numbers in this post and also 
> allows you to look at a
> couple of charts which will help.
>
> A RIP like QTR is, in effect, a set of look up tables which tell the 
> printer how much of each
> ink to put down ...
>
>
> You can simulate this pixel transformation in Photoshop using the 
> Curves function.  Bring
> up a 21 step wedge (or any other file), make sure it is tagged as LAB 
> (either by converting
> or assigning it doesn't matter for this exercise) and look at it.  Now 
> do a curves layer and
> input the co-ordinates that are listed for EEM - 8 bit input to 8 bit 
> equiv output.  You can
> actually cut to the chase and do just the beginning and end - it is a 
> straight line in the
> middle.  The two screen grabs at the bottom of the page show the 
> "curves" for each paper.
> NOW, with Preview checked you can see how your image will be printed 
> with QTR.  (Just
> don't print it with the curve in place else you will double the 
> transformation!)
>
>
>
> Secondly, and this finally answers your soft proof question, we get to 
> use Photoshop's
> built in Preview. When we have a transformation which alters pixel 
> values the effect is
> rendered on screen for us to see.  Thus by having all of the remapping 
> done to the image
> file (temporarily as a separate layer for printing only!!) in a layer 
> we can see the results of
> our work - real time soft proofing!
>
> So in my proposed methodology, I would in essence edit the image to my 
> liking on a well-
> calibrated monitor (this is reason enough to own a photospectrometer) 
> in a workspace
> that matches my print space.  Apply the "print curve" and check my 
> on-screen perfect
> preview of the image (except for ink hue) and maybe tweak the curve 
> for the specifics of
> the paper/ink tonal compression effects on this image, and then print. 
>  I would make sure
> that the "print curve" is saved as a layer because if I then decide to 
> print to glossy paper I
> don't need to compress the tonal range so much and hence I can use a 
> broader curve.
>
> I hope this helps
>
> Steve

Thank you Steve for the lengthly explanation. Ironically, this is 
exactly what I've been doing for previews with the difference that my 
QTR curves are set (by eye) for gamma 2.2 because I can't linearize 
without the densitomiter.

I have also experimented with applying my "s" helper curve directly to 
the QTR curve and building a new QTR curve with the "s" curve built in. 
I would think you could do this as well with a linearized curve as 
well. I suppose this kind of screws up the softproof accuracy though, 
but it is a good curve for printing from applications that are not 
photoshop.

It's been a fun and interesting discussion!

-bruce

Bruce

Rather than messing with the QTR curves you are better off using an Excel spreadsheet to 
compute a PS curve that, together with the curve in the RIP, gives you the "net curve" you 
want.  I gave you the way QTR will remap input to output.  If you layout a sheet with the 
same calcs but add a column for your target curve (graphing this is useful so you can see 
its shape as you alter the numbers) you can then solve for the curve which will remap the 
file values so that when the adjusted values are then remapped by QTR you will get the 
curve you want.  All without a densimeter.

Steve


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, bruce greene <bagreene@v...> 
wrote:

> 
> On Saturday, Dec 11, 2004, at 17:38 US/Pacific, 
> DigitalBlackandWhiteThePrint@yahoogroups.com wrote:
> 
> > Message: 7
> >    Date: Sat, 11 Dec 2004 12:52:49 -0000
> >    From: "Steve Kale" <stevekale@b...>
> > Subject: Re: Re: LAB Step Wedge -- a grayscape Lab space
> >
> >
> > Bruce
> >
> > I am sorry.  I shouldn't have blown you off so fast.  I also should 
> > have added a better
> > explanation when I curtly replied to Roy's post by saying:
> >
> >> So the
> >> existing QTR profiles should work just fine as long as the pixel 
> >> values
> >> don't change, hence Assign-Profile.
> >
> > This would work if the print space was LAB but it isn't.
> >
> >
> >
> > Here is a fuller explanation and also, in effect, a summary of the 
> > other thread.  To explain
> > things more easily, go to this page and download the one page pdf file:
> >
> > http://homepage.mac.com/stevekale/stevekale2/FileSharing37.html
> >
> > It saves me having to put a bunch of numbers in this post and also 
> > allows you to look at a
> > couple of charts which will help.
> >
> > A RIP like QTR is, in effect, a set of look up tables which tell the 
> > printer how much of each
> > ink to put down ...
> >
> >
> > You can simulate this pixel transformation in Photoshop using the 
> > Curves function.  Bring
> > up a 21 step wedge (or any other file), make sure it is tagged as LAB 
> > (either by converting
> > or assigning it doesn't matter for this exercise) and look at it.  Now 
> > do a curves layer and
> > input the co-ordinates that are listed for EEM - 8 bit input to 8 bit 
> > equiv output.  You can
> > actually cut to the chase and do just the beginning and end - it is a 
> > straight line in the
> > middle.  The two screen grabs at the bottom of the page show the 
> > "curves" for each paper.
> > NOW, with Preview checked you can see how your image will be printed 
> > with QTR.  (Just
> > don't print it with the curve in place else you will double the 
> > transformation!)
> >
> >
> >
> > Secondly, and this finally answers your soft proof question, we get to 
> > use Photoshop's
> > built in Preview. When we have a transformation which alters pixel 
> > values the effect is
> > rendered on screen for us to see.  Thus by having all of the remapping 
> > done to the image
> > file (temporarily as a separate layer for printing only!!) in a layer 
> > we can see the results of
> > our work - real time soft proofing!
> >
> > So in my proposed methodology, I would in essence edit the image to my 
> > liking on a well-
> > calibrated monitor (this is reason enough to own a photospectrometer) 
> > in a workspace
> > that matches my print space.  Apply the "print curve" and check my 
> > on-screen perfect
> > preview of the image (except for ink hue) and maybe tweak the curve 
> > for the specifics of
> > the paper/ink tonal compression effects on this image, and then print. 
> >  I would make sure
> > that the "print curve" is saved as a layer because if I then decide to 
> > print to glossy paper I
> > don't need to compress the tonal range so much and hence I can use a 
> > broader curve.
> >
> > I hope this helps
> >
> > Steve
> 
> Thank you Steve for the lengthly explanation. Ironically, this is 
> exactly what I've been doing for previews with the difference that my 
> QTR curves are set (by eye) for gamma 2.2 because I can't linearize 
> without the densitomiter.
> 
> I have also experimented with applying my "s" helper curve directly to 
> the QTR curve and building a new QTR curve with the "s" curve built in. 
> I would think you could do this as well with a linearized curve as 
> well. I suppose this kind of screws up the softproof accuracy though, 
> but it is a good curve for printing from applications that are not 
> photoshop.
> 
> It's been a fun and interesting discussion!
> 
> -bruce

On Monday, Dec 13, 2004, at 10:41 US/Pacific, 
DigitalBlackandWhiteThePrint@yahoogroups.com wrote:

> Message: 5
>    Date: Mon, 13 Dec 2004 16:46:09 -0000
>    From: "Steve Kale" <stevekale@...>
> Subject: Re: LAB Step Wedge -- a grayscape Lab space
>
>
> Bruce
>
> Rather than messing with the QTR curves you are better off using an 
> Excel spreadsheet to
> compute a PS curve that, together with the curve in the RIP, gives you 
> the "net curve" you
> want.  I gave you the way QTR will remap input to output.  If you 
> layout a sheet with the
> same calcs but add a column for your target curve (graphing this is 
> useful so you can see
> its shape as you alter the numbers) you can then solve for the curve 
> which will remap the
> file values so that when the adjusted values are then remapped by QTR 
> you will get the
> curve you want.  All without a densimeter.
>
> Steve


Thanks Steve, but unfortunately this is now going over my head a bit.  
My curves are made by eye using QTR without linearization so they are 
done, I think, using ink percentages. Of course dot gain makes the 
steps uneven over part of the output, so I don't use those ink 
percentages in my curves by limiting the maximum ink out put in each 
ink to where there are clear and even (visually) steps from darkest to 
white. My "raw" or 1st trial profiles come out with near gamma 1.8 
(differs on different papers). I then create a temporary photoshop 
levels adjustment layer to match my test image and step wedge (in gamma 
2.2 working space, viewed on calibrated monitor) to the first trial 
curve print. I then create another temp levels adjustment layer to 
bring the monitor image back to the original look using the levels 
gamma adjustment ( I use the eye dropper to make sure I'm accurate to 
the original file). I then type this gamma adjustment into the ink 
descriptor file and create a new curve. Turning off the temporary 
levels layers, I compare the new curve printout to the original file. 
The match will be quite good. So I've now created a QTR curve for 
gamma2.2 greyscale working space.

To add a little more punch (if I desire) to the QTR curve I create a 
curve adjustment layer temporary layer to add a little punch to my 
original. I save this curve and open and apply it to QTR supplied 
"grayscale-16.psd" file. This is a miniature (pixel wise) grey wedge in 
16bit gamma 2.2 space. I save this file with a new name with the curve 
applied and create a new QTR curve by adding the name of this new 
greyscale file in the curve descriptor line in the ink descriptor text. 
(yea this is going over someones' head!) When the new QTR curve is 
made, my photoshop "s" curve made by eye is now built in to the new QTR 
curve on top of the accurate gamma 2.2 QTR curve. No need for Excel. 
Photoshop provides the graph. It's a mystery how exactly this works as 
the instructions with QTR have "a style all their own" and it took me a 
while to figure out that I needed to actually apply the curve to the 
greywedge and save it under a new name. I guess the QTR curve making 
script examines the contents of this greyscale, notes the changes in 
tonal values and applies these changes to a new QTR curve. It's kind of 
neat actually and very cleaver of Roy I think. How the QTR curve making 
software finds this file is a mystery to me as the instructions don't 
say where (which folder) to save the file in. I saved it in the folder 
with the other curve descriptor files I think.  ***I am using an older 
version of the QTR. If the curve making aspects have changed, then no 
one will understand what I'm saying here!

I would encourage the curious who use QTR on the Mac to try making 
their own curves for quadtone ink sets. It is very educational about 
the way the different inks are laid down and the way a good transition 
works from one density ink to the next. What's really amazing is how 
well the curve making software (ink partitioning) works after one has 
identified the maximum amount of each color ink to lay down. The 
transition is so smooth, with no posterization. If you print 
photographs of people, this is really important. When I used the old 
piezo plug-in, it looked fine on landscapes, but faces always showed 
the poor partitioning of the old plug-in from cone/R9. What I mean by 
this is that if I print a grey gradient from white to black, under an 
8x lupe, I cannot see when one inks stops and the next lighter ink 
starts. Very cool.

enough blabbing...
-bruce

What I meant was that you should do the curves as prescribed by Roy in his
notes and linearize them also according to Roy's instructions (unfortunately
this ideally requires a densimeter but I think some people have used their
scanners).  This way you can also use curves compiled and linearized by
someone else (you only need to look to see what dMin and dMax are in the ink
descriptor file).  If you don't like the linear change in L from dMin to
dMax and the density shift this implies, it is easy to calculate the curve
required in PS which, together with the "(density) curve" in QTR, will get
you the net curve you want.  I think this would be a lot easier than messing
with the inks themselves.  I just did this for my EEM and HPR curves and it
works well.

As an example from my HPR curve, if you know QTR will print value 128 with a
density normally associated with a pixel value of 144 and you want it to
remain 128 (L=50 18% reflectance grey) then you need a curve that maps 128
to 107 in the file before it goes to QTR where 107 gets printed as 128.
Calculating the adjustment curve values is just a process of interpolation.
Probably more accurate than relying on your eye which will be heavily swayed
by the surrounding shades of grey.

> From: bruce greene <bagreene@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Mon, 13 Dec 2004 21:07:56 -0800
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] Re: LAB Step Wedge -- a grayscape Lab space
> 
> 
> 
> On Monday, Dec 13, 2004, at 10:41 US/Pacific,
> DigitalBlackandWhiteThePrint@yahoogroups.com wrote:
> 
>> Message: 5
>>    Date: Mon, 13 Dec 2004 16:46:09 -0000
>>    From: "Steve Kale" <stevekale@...>
>> Subject: Re: LAB Step Wedge -- a grayscape Lab space
>> 
>> 
>> Bruce
>> 
>> Rather than messing with the QTR curves you are better off using an
>> Excel spreadsheet to
>> compute a PS curve that, together with the curve in the RIP, gives you
>> the "net curve" you
>> want.  I gave you the way QTR will remap input to output.  If you
>> layout a sheet with the
>> same calcs but add a column for your target curve (graphing this is
>> useful so you can see
>> its shape as you alter the numbers) you can then solve for the curve
>> which will remap the
>> file values so that when the adjusted values are then remapped by QTR
>> you will get the
>> curve you want.  All without a densimeter.
>> 
>> Steve
> 
> 
> Thanks Steve, but unfortunately this is now going over my head a bit.
> My curves are made by eye using QTR without linearization so they are
> done, I think, using ink percentages. Of course dot gain makes the
> steps uneven over part of the output, so I don't use those ink
> percentages in my curves by limiting the maximum ink out put in each
> ink to where there are clear and even (visually) steps from darkest to
> white. My "raw" or 1st trial profiles come out with near gamma 1.8
> (differs on different papers). I then create a temporary photoshop
> levels adjustment layer to match my test image and step wedge (in gamma
> 2.2 working space, viewed on calibrated monitor) to the first trial
> curve print. I then create another temp levels adjustment layer to
> bring the monitor image back to the original look using the levels
> gamma adjustment ( I use the eye dropper to make sure I'm accurate to
> the original file). I then type this gamma adjustment into the ink
> descriptor file and create a new curve. Turning off the temporary
> levels layers, I compare the new curve printout to the original file.
> The match will be quite good. So I've now created a QTR curve for
> gamma2.2 greyscale working space.
> 
> To add a little more punch (if I desire) to the QTR curve I create a
> curve adjustment layer temporary layer to add a little punch to my
> original. I save this curve and open and apply it to QTR supplied
> "grayscale-16.psd" file. This is a miniature (pixel wise) grey wedge in
> 16bit gamma 2.2 space. I save this file with a new name with the curve
> applied and create a new QTR curve by adding the name of this new
> greyscale file in the curve descriptor line in the ink descriptor text.
> (yea this is going over someones' head!) When the new QTR curve is
> made, my photoshop "s" curve made by eye is now built in to the new QTR
> curve on top of the accurate gamma 2.2 QTR curve. No need for Excel.
> Photoshop provides the graph. It's a mystery how exactly this works as
> the instructions with QTR have "a style all their own" and it took me a
> while to figure out that I needed to actually apply the curve to the
> greywedge and save it under a new name. I guess the QTR curve making
> script examines the contents of this greyscale, notes the changes in
> tonal values and applies these changes to a new QTR curve. It's kind of
> neat actually and very cleaver of Roy I think. How the QTR curve making
> software finds this file is a mystery to me as the instructions don't
> say where (which folder) to save the file in. I saved it in the folder
> with the other curve descriptor files I think.  ***I am using an older
> version of the QTR. If the curve making aspects have changed, then no
> one will understand what I'm saying here!
> 
> I would encourage the curious who use QTR on the Mac to try making
> their own curves for quadtone ink sets. It is very educational about
> the way the different inks are laid down and the way a good transition
> works from one density ink to the next. What's really amazing is how
> well the curve making software (ink partitioning) works after one has
> identified the maximum amount of each color ink to lay down. The
> transition is so smooth, with no posterization. If you print
> photographs of people, this is really important. When I used the old
> piezo plug-in, it looked fine on landscapes, but faces always showed
> the poor partitioning of the old plug-in from cone/R9. What I mean by
> this is that if I print a grey gradient from white to black, under an
> 8x lupe, I cannot see when one inks stops and the next lighter ink
> starts. Very cool.
> 
> enough blabbing...
> -bruce