Digital BW, The Print

Appendix 2 of Tom Moore's very useful Tutorial on making curves for QTR
says, "quacvraw is a way to convert a photoshop curve into a QuadToneRIP
curve.

 

How do these work?

 

What kinds of Photoshop curves are covered?

 

Does it work for all Epson printers?  Hextone included?

 

Thanks.

 

Paul

www.PaulRoark.com <http://www.paulroark.com/>  

 



[Non-text portions of this message have been removed]

Paul,

Yes QTR will work VERY well with Hextone inks in the supported 
printers, which include most of the useful ones.  About "qacvraw", I 
have not had any use for it.  But I can assure you, you cannot use 
the RGB partition curves you have created for Hextone inks.

QTR is actually sweet with any ink design you care to throw at it.  
It limits each ink channel individually, so you no longer rely on 
the "paper setting" in the Epson driver for that.  It partitions the 
inks you CHOOSE to use according to tone, and finally, it linearizes 
the tonal response from DMax to DMin.  And you CHOOSE to use ink 
channels as you desire, creating curves specific to your choice.  Let 
me give you an example of what I am working on on my 1280 right now:


K = Ebony, C = UT FS Neutral Dark, M = UT FS Warm Dark, LC = UT FS 
Neutral Medium, LM = UT FS Warm Medium, Y = UT FS Warm Light + Yellow 
UC Clone (I am tweaking the right mix).

With this set-up, I can print;

(1) all warm using just the K, M, and LM channels.
(2) all neutral using just the K, C, and LC channels
(3) a mix of "warm" and "neutral" across the entire tonal range (in 
10% steps)
(4) split-toned neutal/cool shadows to warm/gold highlights using K, 
C, LC, and Y channels.
(5) spilt-toned warm shadows to neutral highlights using K, M, and LC 
channels.
(5) Many other variations and mixes thereof.

Pretty nifty, if you ask me.  Once you get used to the method, it is 
really easy.  The great thing is that you are not affacting the 
integrity of the image file in the image editor.  So no 
posterization - ever!

With all due respect to you and your ink designs and curves methods, 
QTR takes them to a whole new realm of possibilities.  I can spend 
time designing the look I want with the inks, and NOT have to then 
slave at making the printer behave according to my whims.  QTR takes 
care of that.

Best regards.

Shilesh

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@v...> wrote:
> Appendix 2 of Tom Moore's very useful Tutorial on making curves for 
QTR
> says, "quacvraw is a way to convert a photoshop curve into a 
QuadToneRIP

> curve.
> 
>  
> 
> How do these work?
> 
>  
> 
> What kinds of Photoshop curves are covered?
> 
>  
> 
> Does it work for all Epson printers?  Hextone included?
> 
>  
> 
> Thanks.
> 
>  
> 
> Paul
> 
> www.PaulRoark.com <http://www.paulroark.com/>  
> 
>  
> 
> 
> 
> [Non-text portions of this message have been removed]

Paul

I can guess but can't answer your question from actual knowledge. You'll
have to rely on Roy Harrington or perhaps Daniel Staver for a definitive
answer.

The material in the tutorial was copied from information originally prepared
by Roy for the Mac version. The qacvraw program uses a specific file
cmyk-16.psd that I cannot find in any distribution of material I have from
Roy.

My guess is that cmyk-16.psd must be something like a linear 256 step wedge
that can be adjusted by a curve and saved in photoshop raw format.
Subsequently qacvraw can be used to read one of the 4 channels in the
"curved" raw format file and output it as a QTR curve, thereby creating a
QTR curve that is the image of the photoshop curve. Note that a QTR curve is
simply a sequence of 256 16 bit numbers. A QTR .quad file (confusingly,
sometimes also called a curve) is a concatenation of 4, 6 or 7 curves,
depending on the printer it is designed for.

Hope this is helpful and not too misleading.

Tom Moore

> -----Original Message-----
> From: Paul Roark [mailto:paul.roark@...]
> Sent: Friday, April 08, 2005 11:31 PM
> To: DigitalB&WPrint
> Subject: [Digital BW] QTR Question: how does "qacvraw" work?
> 
> 
> Appendix 2 of Tom Moore's very useful Tutorial on making curves for QTR
> says, "quacvraw is a way to convert a photoshop curve into a QuadToneRIP
> curve.
> 
> 
> 
> How do these work?
> 
> 
> 
> What kinds of Photoshop curves are covered?
> 
> 
> 
> Does it work for all Epson printers?  Hextone included?
>

The qacvraw program only works with special .RAW files that Roy created 
while qacv works with Photoshop .ACV curves.

The qacv program will output the curve points of the first channel in a 
Photoshop curve as a set of x,y coordinates. Then you can use the qcurve 
program to transform these coordinates into 256 16bit values. These 
values can be used for one ink channel in QTR.

In the latest, not yet released, version of QuadProfile and QTRgui we 
support loading a Photoshop curve for any individual ink channel. If the 
Photoshop curve has more than one channel the first will be used and the 
others discarded.

If you wanted to you could create a curve for every ink channel and 
effectively bypass the entire profiling process in QTR and have full 
manual control of every ink channel. A more reasonable approach would 
perhaps to use this for special curves like GLOP curves where the curve 
for the GLOP ink might have an unusual shape and you'd want full manual 
control.

You can also load a photoshop curve to modify a partitioned gray or 
toner curve. This has always been supported.

In addition to this you can manually enter curve points directly into 
QTRgui instead of using the photoshop file format. Up to 50 curve points 
  are supported.

This works for all printers, the only difference is the amount of ink 
channels you have available to work with.

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

> Appendix 2 of Tom Moore's very useful Tutorial on making curves for QTR
> says, "quacvraw is a way to convert a photoshop curve into a QuadToneRIP
> curve.
> 
> How do these work?
> 
> What kinds of Photoshop curves are covered?
> 
> Does it work for all Epson printers?  Hextone included?

The .raw files are just saved in Photoshop RAW format.  The files files
just contain the data of an image file -- no headers or formatting of
any kind.  I created 16-bit PS files that just had 256 pixels, one of
each possible gray value.   You can then apply a .acv curve to it and
save the result as a .raw.   The .raw will now contain the exact curve
transformation which can then be used as a component of a QTR
.quad file.  So qacvraw takes one channel of a raw file and converts it 
from binary to text i.e. .quad format.   You can do grayscale with one
channel or any number of channels 4,6,7,8 by just making the original
PS file and .acv N channels.  A minor issue is that PC and Mac store the
bytes in opposite order.   The other program qacv extracts (x,y)
coordinates out of a .acv file which can be connected and smoothed.

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Daniel Staver 
<daniel@p...> wrote:

> The qacvraw program only works with special .RAW files that Roy created 
> while qacv works with Photoshop .ACV curves.
> 
> The qacv program will output the curve points of the first channel in a 
> Photoshop curve as a set of x,y coordinates. Then you can use the qcurve 
> program to transform these coordinates into 256 16bit values. These 
> values can be used for one ink channel in QTR.
> 
> In the latest, not yet released, version of QuadProfile and QTRgui we 
> support loading a Photoshop curve for any individual ink channel. If the 
> Photoshop curve has more than one channel the first will be used and the 
> others discarded.
> 
> If you wanted to you could create a curve for every ink channel and 
> effectively bypass the entire profiling process in QTR and have full 
> manual control of every ink channel. A more reasonable approach would 
> perhaps to use this for special curves like GLOP curves where the curve 
> for the GLOP ink might have an unusual shape and you'd want full manual 
> control.
> 
> You can also load a photoshop curve to modify a partitioned gray or 
> toner curve. This has always been supported.
> 
> In addition to this you can manually enter curve points directly into 
> QTRgui instead of using the photoshop file format. Up to 50 curve points 
>   are supported.
> 
> This works for all printers, the only difference is the amount of ink 
> channels you have available to work with.
> 
> --
> Daniel Staver
> http://daniel.staver.no
> 
> > Appendix 2 of Tom Moore's very useful Tutorial on making curves for QTR
> > says, "quacvraw is a way to convert a photoshop curve into a QuadToneRIP
> > curve.
> > 
> > How do these work?
> > 
> > What kinds of Photoshop curves are covered?
> > 
> > Does it work for all Epson printers?  Hextone included?

Roy,

 
> The .raw files are just saved in Photoshop RAW format.

My XP system with PS CS can save in Photoshop (*.psd); I'm not familiar with
the "RAW" version.

>  The files files
> just contain the data of an image file -- no headers or formatting of
> any kind. 

Is this something that is doable by Photoshop?


> I created 16-bit PS files that just had 256 pixels, one of
> each possible gray value.   You can then apply a .acv curve to it and
> save the result as a .raw.   The .raw will now contain the exact curve
> transformation which can then be used as a component of a QTR
> .quad file.

So, it acts as, in effect, a translation interface between the formats?

Have you looked at the text file that Picture Window (an *acv-compatible
application) allows to be edited?

>  So qacvraw takes one channel of a raw file and converts it
> from binary to text i.e. .quad format.   You can do grayscale with one
> channel or any number of channels 4,6,7,8 by just making the original
> PS file and .acv N channels.

It seems to me that the conversion is one .acv curve to one .quad (?) curve.
That sounds doable.

With the .acv curves, however, the Epson driver crossovers are in a black
box.  Unless the conversion program contained information about the Epson
driver cross-overs, I can not see how the program could map a .acv curve to
the 2 QTR curves that would be needed for the, for example, C - LC
crossover.

Then there is the lack of black ink crossover information.

Conversion might not be worth the work.

>  A minor issue is that PC and Mac store the
> bytes in opposite order.   


>The other program qacv extracts (x,y)
> coordinates out of a .acv file which can be connected and smoothed.

Unless there is crossover information & algorithms, this faces the same
problems.

I think the rips would benefit from having pre-made ink pairs that were
based on reverse-engineered, printer-specific printer crossovers, at least
for C-LC and M-LM.  One could put clear in alternating chambers and extract
this information rather easily.  The Black-LK-CMY cross-over sounds like a
bear.

Paul
www.PaulRoark.com 

__________________________________

> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Daniel Staver
> <daniel@p...> wrote:
> > The qacvraw program only works with special .RAW files that Roy created
> > while qacv works with Photoshop .ACV curves.
> >
> > The qacv program will output the curve points of the first channel in a
> > Photoshop curve as a set of x,y coordinates. Then you can use the qcurve
> > program to transform these coordinates into 256 16bit values. These
> > values can be used for one ink channel in QTR.
> >
> > In the latest, not yet released, version of QuadProfile and QTRgui we
> > support loading a Photoshop curve for any individual ink channel. If the
> > Photoshop curve has more than one channel the first will be used and the
> > others discarded.
> >
> > If you wanted to you could create a curve for every ink channel and
> > effectively bypass the entire profiling process in QTR and have full
> > manual control of every ink channel. A more reasonable approach would
> > perhaps to use this for special curves like GLOP curves where the curve
> > for the GLOP ink might have an unusual shape and you'd want full manual
> > control.
> >
> > You can also load a photoshop curve to modify a partitioned gray or
> > toner curve. This has always been supported.
> >
> > In addition to this you can manually enter curve points directly into
> > QTRgui instead of using the photoshop file format. Up to 50 curve points
> >   are supported.
> >
> > This works for all printers, the only difference is the amount of ink
> > channels you have available to work with.
> >
> > --
> > Daniel Staver
> > http://daniel.staver.no
> >
> > > Appendix 2 of Tom Moore's very useful Tutorial on making curves for
> QTR
> > > says, "quacvraw is a way to convert a photoshop curve into a
> QuadToneRIP
> > > curve.
> > >
> > > How do these work?
> > >
> > > What kinds of Photoshop curves are covered?
> > >
> > > Does it work for all Epson printers?  Hextone included?
> 
> 
> 
> 
> 
> 
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--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark" 
<paul.roark@v...> wrote:
> Roy,
> 
>  
> > The .raw files are just saved in Photoshop RAW format.
> 
> My XP system with PS CS can save in Photoshop (*.psd); I'm not familiar with
> the "RAW" version.

It's one of the formats in Save As.

> 
> >  The files files
> > just contain the data of an image file -- no headers or formatting of
> > any kind. 
> 
> Is this something that is doable by Photoshop?

Yes, but it's a write-only format.   You don't get any info about what the
data is.  I use the file size in bytes as the only clue.
   Nchannels = Nbytes / 256pixels / 2          (2=bytes/pixel)

It's a pretty useless format unless you create it for a very specific reason.

> 
> 
> > I created 16-bit PS files that just had 256 pixels, one of
> > each possible gray value.   You can then apply a .acv curve to it and
> > save the result as a .raw.   The .raw will now contain the exact curve
> > transformation which can then be used as a component of a QTR
> > .quad file.
> 
> So, it acts as, in effect, a translation interface between the formats?

Essentially yes.  I'm using it to get the whole curve from a .acv -- including
all the smoothing between points.  Now I have some spline code that
I can do the smoothing -- only issue is that it's not identical to PS's.

> 
> Have you looked at the text file that Picture Window (an *acv-compatible
> application) allows to be edited?

No.  But the .acv's are pretty simple so making a text version wouldn't
be too hard.

> 
> >  So qacvraw takes one channel of a raw file and converts it
> > from binary to text i.e. .quad format.   You can do grayscale with one
> > channel or any number of channels 4,6,7,8 by just making the original
> > PS file and .acv N channels.
> 
> It seems to me that the conversion is one .acv curve to one .quad (?) curve.
> That sounds doable.

Yes, they (both .acv and .quad) can be multiple channels.  The qacv & qacvraw
do one channel at a time.   The .quad's are just concatenations of multiple
channels.

> 
> With the .acv curves, however, the Epson driver crossovers are in a black
> box.  Unless the conversion program contained information about the Epson
> driver cross-overs, I can not see how the program could map a .acv curve to
> the 2 QTR curves that would be needed for the, for example, C - LC
> crossover.

Your usage of RGB .acv's that will go though the Epson driver is a totally
different thing for the reasons you stated.  I'm using them for the individual
inks like K C M Y LC LM LK.  QTR has "crossover" or partitioning capability
builtin -- you just have to specify a single density to have the partitioning
done for you.

> 
> Then there is the lack of black ink crossover information.
> 
> Conversion might not be worth the work.
> 
> >  A minor issue is that PC and Mac store the
> > bytes in opposite order.   
> 
> 
> >The other program qacv extracts (x,y)
> > coordinates out of a .acv file which can be connected and smoothed.
> 
> Unless there is crossover information & algorithms, this faces the same
> problems.
> 
> I think the rips would benefit from having pre-made ink pairs that were
> based on reverse-engineered, printer-specific printer crossovers, at least
> for C-LC and M-LM.  One could put clear in alternating chambers and extract
> this information rather easily.  The Black-LK-CMY cross-over sounds like a
> bear.

Again this is all an RGB Epson driver problem, none of this is an issue if you go to
the individual inks.

Roy

> 
> Paul
> www.PaulRoark.com 
> 
> __________________________________
>  
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Daniel Staver
> > <daniel@p...> wrote:
> > > The qacvraw program only works with special .RAW files that Roy created
> > > while qacv works with Photoshop .ACV curves.
> > >
> > > The qacv program will output the curve points of the first channel in a
> > > Photoshop curve as a set of x,y coordinates. Then you can use the qcurve
> > > program to transform these coordinates into 256 16bit values. These
> > > values can be used for one ink channel in QTR.
> > >
> > > In the latest, not yet released, version of QuadProfile and QTRgui we
> > > support loading a Photoshop curve for any individual ink channel. If the
> > > Photoshop curve has more than one channel the first will be used and the
> > > others discarded.
> > >
> > > If you wanted to you could create a curve for every ink channel and
> > > effectively bypass the entire profiling process in QTR and have full
> > > manual control of every ink channel. A more reasonable approach would
> > > perhaps to use this for special curves like GLOP curves where the curve
> > > for the GLOP ink might have an unusual shape and you'd want full manual
> > > control.
> > >
> > > You can also load a photoshop curve to modify a partitioned gray or
> > > toner curve. This has always been supported.
> > >
> > > In addition to this you can manually enter curve points directly into
> > > QTRgui instead of using the photoshop file format. Up to 50 curve points
> > >   are supported.
> > >
> > > This works for all printers, the only difference is the amount of ink
> > > channels you have available to work with.
> > >
> > > --
> > > Daniel Staver
> > > http://daniel.staver.no
> > >
> > > > Appendix 2 of Tom Moore's very useful Tutorial on making curves for
> > QTR
> > > > says, "quacvraw is a way to convert a photoshop curve into a
> > QuadToneRIP
> > > > curve.
> > > >
> > > > How do these work?
> > > >
> > > > What kinds of Photoshop curves are covered?
> > > >
> > > > Does it work for all Epson printers?  Hextone included?
> > 
> > 
> > 
> > 
> > 
> > 
> > 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
> > 
> > 
> > 
> > 
> > 
> >