Digital BW, The Print

Antonis,

From what you say below IJC/OPM would seem to be going in the ideal
direction. Basically it is offering the best of both worlds. It gives you
"canned profiles" to get started with and to stay with if that satisfies the
artist's requirements, and at the same time is open to in-depth tweaking for
people who want or need to take things further.

The plug-in is great but not being able to open up a profile and customize
it yourself has been frustrating. That said, getting into things at that
level is no small task.

One of the things that really strikes me at this point is that there have
been wildly different experiences among users with the same software and
inks. Some people do really well with a given system and others experience
total failure with every possible degree of success in between. After going
through a 1270 and three 1280's I think that the problem lies in a huge
amount of variation from printer-to-printer within a given model. This makes
things a bit of a crap shoot. Maybe your printer handles the canned software
well and maybe not. The ability to dial things in for your equipment sounds
great.

I would be very curious to see a print made with the plug-in compared to a
print made with an optimized IJC/OPM profile from the same printer.

As you very accurately point out we really don't know how much of the PS
adjustment we ultimately do on an image is driven by the need to correct
problems in the system. About all most of us can do is make a print,
evaluate it, make changes in PS, make another print and keep repeating this
cycle until we reach a satisfactory print.

IJC/OPM or something like it might or might not produce a better print than
a canned approach depending upon how far off any particular printer is from
the "ideal" printer that was used to create the canned software. If a
printer is too far off, it is conceivable that you could not get an optimum
print with canned software since you might have to adjust the image in PS to
the point where data is being lost.

This then comes back to the idea that if you have a smooth running system in
place that gives good prints then you may be better off making prints than
pursuing the "perfect system". On the other hand if a you are not able to
get a satisfying print of a significant number of your images IJC/OPM looks
like a very good option to explore.

While the appeal is the ability to match the profile to the printer, wide
spread use will probably depend upon the number of printers, ink sets and
papers supported with canned profiles. Is the base of available profiles a
growing or are things still pretty much in a development stage in this
regard?

The one thing that still seems elusive is the creation of the separation or
partitioning curves. The decision of where and how to bleed one ink into
another on the tonal ramp seems to remain as much art as science. Does
IJC/OPM have any tools to help in this regard or is it still by feel as it
was doing CYMK separation curves for use with RIP's in the early days of
quad printing?

Thanks for the feedback and explanations.

Martin


----- Original Message ----- 
From: "Antonis Ricos" <antonisphoto@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Thursday, June 05, 2003 6:30 PM
Subject: [Digital BW] Re: OPM in theory (to Martin's q.)


>
> > Would this be a case where converting back to 16-bit just prior to
printing
> > would be in order?
>
>
> Martin,
>
> yes, exactly - or to 720dpi  for that matter.
>
>
> >
> > I know you beta tested the IJC/OPM software and are a long time user of
the
> > Piezo/R9 plug-in. Can you give us your comparison of print quality and
> > workflow quality of the two?
>
> well.... yes, I suppose I should. I would need to print the same file both
ways
> and upload detailed scans of the prints. I can do that with the 1280/PT
> seleniums. ..   OK, "coming soon"....
>
> Meanwhile, by way of a (lengthy) prologue:
>
> The main difference between IJC/OPM and systems that use canned profiles
> is not just the accurate match of the profile to the user's system but the
fact that
> you gain "analogue" control of the tonal distribution of your print.  This
applies
> to any Raster Image Processor that gives you single channel control of the
> printer, not just OPM.
>
> When you tweak RGB curves, or  tweak a grayscale file based on a monitor
> preview (or printed output) you are altering the digital data in the
picture.
> That's normally where people are careful with scans and histograms, do
some
> moves in 16bit etc. trying protect the tonal integrity of that data.  I
call that
> "digital" corrections or adjustments that take place  in the digital
domain.
>
> When you tweak how much ink - and in what combination of colors or grays -
> is layed down for each digital value in the image, you are performing an
> "analogue" correction. Sure, it's handled digitally, but it is not
dependent on
> the digital data in the image file. It only becomes related to it  when
the
> software "looks up" the digital value in the image and matches it up with
your
> choice of amount of ink(s). In this scenario, you can lighten/darken etc
without
> affecting the precious bits and bytes in the original file. I call it
"analogue",
> (like audio D/A converters) because it occurs at the point where pixels
are
> converted into the appearance of a continuous tone print.
>
> This "analogue" option is not available when the controls are locked away
in a
> black box like the Epson driver or the R9 plug in or ImagePrint etc. Now,
there
> may be good reasons for locking them away - there is serious complexity in
> reproducing CcMmYK color prints from RGB files and companies like
> Colorbyte have brought a lot of science to help us out.
> In the case of bw, it takes  a fairly knowledgable user to make a profile
and
> understand how you partiton the grayscale into the 2-7 inks you may be
using
> to print. So, this may not be for everyone, and there may be plenty of
happy
> users of canned profiles (as Tyler points out) - fair enough.  Of course,
as
> profiles become available for OPM, not only are they canned and
easy-to-use,
> the whole thing is free, which is another matter to consider!
>
> By the same token, we need to be aware of what we are doing to our digital
> data when (and if) we have to twist it because of  inaccuracies in our
printing
> systems. When you make a bw print with a "locked" system, then adjust your
> image to improve that print, some of the adjustments are part of  the
artistic
> interperetation, of course, but a fair amount may be aimed at
counteracting
> the effects of an out-of-whack system. You will never be able to separate
the
> two without  access to the print controls of the driver independently of
the
> image file.
>
> So, these are the theoretical reasons for seeking out systems that allow
> "analogue"  tweaks. Now, it doesn't mean that everything else is garbage,
nor
> that the ability to have these controls automatically makes a software
superior.
> I am happy to see the introduction into the arena of monochrome printing
of
> the Ergosoft product (at inkjetmall), because it appears to address the
issues I
> am talking about. I have not had any experience with it (because I am
> Windoze-challenged) but have pretty high hopes for its performance based
on
> reviews and on line discussions.  It may be several times the cost of IJC,
but I
> believe it also supports more large format printers without the
limitations of
> IJC. We've seen leapfrogging before - let's see what's in store next....
>
> Antonis
>
>
>
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>

---  "Martin Wesley" <mwesley250@e...> wrote:
....
> 
> The one thing that still seems elusive is the creation of the 
separation or
> partitioning curves. The decision of where and how to bleed 
one ink into
> another on the tonal ramp seems to remain as much art as 
science. Does
> IJC/OPM have any tools to help in this regard or is it still by feel 
as it
> was doing CYMK separation curves for use with RIP's in the 
early days of
> quad printing?
> 
> Thanks for the feedback and explanations.
> 
> Martin
> 

---  Kevin Gulstene <kevin@d...> wrote:
> Roy-
> 
> > For anyone considering this, a machine that can run OS X
> > might be well worth it.  The next QuadToneRIP will have 
some
> > significant new capabilities.  Transfer of files via ethernet
> > ought to be very easy.
> >
> > Roy
> 
> Any hints what these new capabilities may be?
> 
> 
> --
> Kevin
> http://www.dockwalker.com

Kevin, Martin etal

I've been away at a graduation for a few days and I see there's 
been
lots of action about partitioning and new workflows.

I'm not much for pre-announcing things -- but I guess I've got to 
say
some about QuadToneRIP.   In between a bunch of other things 
I've
managed to upgrade to a new version.

First QuadToneRIP 2.0 now has all the obvious stuff:
1) Separate control of all 4, 6, and 7 ink epson printers.
2) All curves are internally 16 bit to match the gimp-print 
internals.
3) blending of two curves for neutral--to--toned ink sets.

After working for a while with these "raw" 16-bit curves, I found 
that
partitioning at this level is very simple.  So the new and exciting
thing is another program I'm calling QuadProfile.  With a couple
of very straightforward calibration steps to measure the relative
densities of the various inks, all the partitioning curves are
generated automatically.  This works for any set and any number
of inks.  The generated curves give a monotonically increasing
density but the exact shape can be customized.  Adding toner to
the gray is fairly easy but manual so far.

I'm sure this will raise lots of questions so here's a few answers:

System?
This is a Mac OS X system -- Linux if you do the port.

Printers?
Any Epson printer supported by Gimp-print is possible.  I'm
figuring on all the 4-digit model numbers, and several of the
3-digit models (860,870,890,960,980).  Others?

When?  
The basic QuadToneRIP code has been running for quite a 
while.
The QuadProfile system is working on my computer, but it's
currently several programs and shell scripts to connect it all
together.  I've been working on putting this all in one program
and one descriptor file.  I have a lot of printing that I need to
do this month, so work on this is lower priority -- sorry.  If
anyone is familar with running shell scripts and the Terminal
program, a beta version with shell scripts can be used.  Email 
me at
quadtone <at> harrington <dot> com

Densitometer?
It's certainly a very useful tool, but I've been able to get good
results trying a flatbed scanner for the partitioning.  Contrast  
decisions can for the most part be done visually.

Roy Harrington
www.harrington.com

Martin,

there may be more OPM profiles in the future, but this isn't necessarily a 
commitment on the part of Bowhaus. They may share profiles they make for 
themselves as much as I and others may share here on the list.  The only 
limitation to this free-flow is that increasingly IJC users will take advantage of 
the individual ink controls and load up their inks in a non-standard order.  That 
would make for yet another variable in the matching game. 

Development of OPM - not just profiles - seems to proceed very slowly;  bursts 
of new stuff and real progress followed by periods of complete stagnation. If 
you look at their web site, Bowhaus is primarily a company that offers 
scanning and printing services. IJC is a byproduct of their inhouse needs. In 
that sense, IJC is here to stay and has a long future, but at the same time 
development isn't likely to proceed at the pace a real software company might 
be able to sustain.  If they only figured out how to support the large format 
printers without the present limitations,  their pricing would make this the 
bargain of the decade. But  it is what it is, and when they are ready to move to 
the next revision we'll see what happens.



As for tools to help with partitioning the inks, there is indirect help within IJC, 
but no "tools" per se.  Deciding where to start an ink and how to taper it off, 
however, isn't as difficult as it sounds. A new user has plenty of existing 
profiles as guides, and the software has an amazing feature in which it can 
automatically print all active inks (jets) separately one after the other in a 
0-100% grayscale. So you get to see what each ink is doing as well as a 
composite of all these together in a separate grayscale.
 
 If you look closely at the composite grayscale, you begin to see the effects of 
bringing, say. a darker ink into the lighter values: you see the device dots that 
happen as the ink starts to kick in. By moving it further down "under" the 
heavier densities of the lighter ink, you can successfully hide those dots.  

It's actually fun to play with this because soon you will realize the benefit of 
the smaller-drop-size printers: you can get away with bringing a darker ink 
further up towards lighter values because the smaller device dots don't 
become apparent quite so easily. Thus a 2200 has a huge advantage over, 
say, a 7000 which appears clunky by comparison. Or, by the same approach, 
you get to use all 6 inks in a 7000 to hide its dots much better  than software 
that only uses 4 inks. Plus you know what each nozzle does. IP, as an 
example,  randomly picks among the pair of inks of the same density (Cyan / 
Photo Cyan, Magenta / Photo Magenta) in an effort to equalize their usage. If 
you have a bad nozzle in one of your heads, good luck tracking it down, plus 
you are waisting 2 ink positions that could be used as toners.

Another consideration in  adjusting how "soon" a darker ink comes into the 
gray scale has to do with the total load of ink that is layed down  for that part of 
the scale. Less actual fluid is needed to produce the same density with a 
darker ink than with a lighter one. Something to think about when tweaking to 
reduce bronzing in glossy papers, for example.

All this is swell and wonderful, as they say, except it won't run on your PC - so 
how about we swap one of my Macs for one of your PCs and then I get to test 
the Ergosoft RIP!...  : - )

Oh well, enough theory - let's go make some prints now....


Antonis



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Martin Wesley" 
<mwesley250@e...> wrote:
> Antonis,
> 
> From what you say below IJC/OPM would seem to be going in the ideal
> direction. Basically it is offering the best of both worlds. It gives you
> "canned profiles" to get started with and to stay with if that satisfies the
> artist's requirements, and at the same time is open to in-depth tweaking for
> people who want or need to take things further.
> 
> The plug-in is great but not being able to open up a profile and customize
> it yourself has been frustrating. That said, getting into things at that
> level is no small task.
> 
> One of the things that really strikes me at this point is that there have
> been wildly different experiences among users with the same software and
> inks. Some people do really well with a given system and others experience
> total failure with every possible degree of success in between. After going
> through a 1270 and three 1280's I think that the problem lies in a huge
> amount of variation from printer-to-printer within a given model. This makes
> things a bit of a crap shoot. Maybe your printer handles the canned software
> well and maybe not. The ability to dial things in for your equipment sounds
> great.
> 
> I would be very curious to see a print made with the plug-in compared to a
> print made with an optimized IJC/OPM profile from the same printer.
> 
> As you very accurately point out we really don't know how much of the PS
> adjustment we ultimately do on an image is driven by the need to correct
> problems in the system. About all most of us can do is make a print,
> evaluate it, make changes in PS, make another print and keep repeating 
this
> cycle until we reach a satisfactory print.
> 
> IJC/OPM or something like it might or might not produce a better print than
> a canned approach depending upon how far off any particular printer is from
> the "ideal" printer that was used to create the canned software. If a
> printer is too far off, it is conceivable that you could not get an optimum
> print with canned software since you might have to adjust the image in PS to
> the point where data is being lost.
> 
> This then comes back to the idea that if you have a smooth running system 
in

> place that gives good prints then you may be better off making prints than
> pursuing the "perfect system". On the other hand if a you are not able to
> get a satisfying print of a significant number of your images IJC/OPM looks
> like a very good option to explore.
> 
> While the appeal is the ability to match the profile to the printer, wide
> spread use will probably depend upon the number of printers, ink sets and
> papers supported with canned profiles. Is the base of available profiles a
> growing or are things still pretty much in a development stage in this
> regard?
> 
> The one thing that still seems elusive is the creation of the separation or
> partitioning curves. The decision of where and how to bleed one ink into
> another on the tonal ramp seems to remain as much art as science. Does
> IJC/OPM have any tools to help in this regard or is it still by feel as it
> was doing CYMK separation curves for use with RIP's in the early days of
> quad printing?
> 
> Thanks for the feedback and explanations.
> 
> Martin

I've been working with Roy's beta of 2.0 for a couple weeks now and I couldn't be 
happier so far. No conclusive results from me, since I have had some higher-priority 
work on my queue and since I am testing ultratones and the new qtr at the same 
time, but so far so good :)

> If you look at their web site, Bowhaus is primarily a company that
> offers scanning and printing services. IJC is a byproduct of their
> inhouse needs. 

> ... the software has an amazing feature in which it can 
> automatically print all active inks (jets) separately one
> after the other in a 0-100% grayscale. So you get to see what
> each ink is doing as well as a composite of all these together
> in a separate grayscale

Sounds like OPM/IJC is a prime example of two fundamental rules of
software tools:

(1) the best software tools are written poeple who are actually
	using the tools

(2) the quality of software is inversely proportioinal to what you
	pay for it

John

----- Original Message ----- 

From: "Antonis Ricos" <antonisphoto@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, June 06, 2003 1:00 AM
Subject: [Digital BW] Re: OPM in theory (to Martin's q.)


> Martin,
>
> there may be more OPM profiles in the future, but this isn't necessarily a
> commitment on the part of Bowhaus. They may share profiles they make for
> themselves as much as I and others may share here on the list.  The only
> limitation to this free-flow is that increasingly IJC users will take
advantage of
> the individual ink controls and load up their inks in a non-standard
order.  That
> would make for yet another variable in the matching game.

Antonis,

I really wasn't thinking that Bowhaus would provide a lot of profiles but
rather that new profiles would be shared by users. Some general standards on
ink order would be helpful though but obviously voluntary.
>
> Development of OPM - not just profiles - seems to proceed very slowly;
bursts
> of new stuff and real progress followed by periods of complete stagnation.
If
> you look at their web site, Bowhaus is primarily a company that offers
> scanning and printing services. IJC is a byproduct of their inhouse needs.
In
> that sense, IJC is here to stay and has a long future, but at the same
time
> development isn't likely to proceed at the pace a real software company
might
> be able to sustain.  If they only figured out how to support the large
format
> printers without the present limitations,  their pricing would make this
the
> bargain of the decade. But  it is what it is, and when they are ready to
move to
> the next revision we'll see what happens.
>
> As for tools to help with partitioning the inks, there is indirect help
within IJC,
> but no "tools" per se.  Deciding where to start an ink and how to taper it
off,
> however, isn't as difficult as it sounds. A new user has plenty of
existing
> profiles as guides, and the software has an amazing feature in which it
can
> automatically print all active inks (jets) separately one after the other
in a
> 0-100% grayscale. So you get to see what each ink is doing as well as a
> composite of all these together in a separate grayscale.

That sounds pretty slick. Are you using this to fine tune individual prints
or just the prewritten profiles?
>
>  If you look closely at the composite grayscale, you begin to see the
effects of
> bringing, say. a darker ink into the lighter values: you see the device
dots that
> happen as the ink starts to kick in. By moving it further down "under" the
> heavier densities of the lighter ink, you can successfully hide those
dots.
>
> It's actually fun to play with this because soon you will realize the
benefit of
> the smaller-drop-size printers: you can get away with bringing a darker
ink
> further up towards lighter values because the smaller device dots don't
> become apparent quite so easily. Thus a 2200 has a huge advantage over,
> say, a 7000 which appears clunky by comparison. Or, by the same approach,
> you get to use all 6 inks in a 7000 to hide its dots much better  than
software
> that only uses 4 inks. Plus you know what each nozzle does. IP, as an
> example,  randomly picks among the pair of inks of the same density (Cyan
/
> Photo Cyan, Magenta / Photo Magenta) in an effort to equalize their usage.
If
> you have a bad nozzle in one of your heads, good luck tracking it down,
plus
> you are waisting 2 ink positions that could be used as toners.

Interesting about the 2200 vs. the 7000. Where do you think the 7600 falls
in comparison?
>
> Another consideration in  adjusting how "soon" a darker ink comes into the
> gray scale has to do with the total load of ink that is layed down  for
that part of
> the scale. Less actual fluid is needed to produce the same density with a
> darker ink than with a lighter one. Something to think about when tweaking
to
> reduce bronzing in glossy papers, for example.
>
> All this is swell and wonderful, as they say, except it won't run on your
PC - so
> how about we swap one of my Macs for one of your PCs and then I get to
test
> the Ergosoft RIP!...  : - )

Too bad I don't have that 386 with the 8 MB of DIMM chip RAM. I could make
you a great deal. Actually this could be a great opportunity for Mac users
to sell off older machines to PC users for OPM and buy newer Mac's. Wait a
minute! Do I smell a conspiracy here!<G>
>
> Oh well, enough theory - let's go make some prints now....

You don't get much mileage on the list doing that. <G>

(snip earlier)

----- Original Message ----- 

From: "Tyler Boley" <tyler@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, June 06, 2003 11:53 AM
Subject: [Digital BW] Re: OPM in theory (to Martin's q.)


> I feel like the godfather character- I keep trying to get out and they
> keep dragging me back in!

Tyler,

You know where all the bodies are buried and we can let you leave. Not alive
at least. You simply know too much.<G>

(For those who don't know, Tyler has probably been doing quad grayscale
inkjet printing as long or longer than anyone else on the list and is still
printing with his 3000, custom CMYK separation curves and PressReady RIP to
make some of the very finest prints I have ever seen. Totally from the stone
age back about 1998 or earlier. <G>)

(snip earlier)

> For mono printing systems, we may have a master 16 bit gamma 2.2 (for
> example) file. Our output system, whether Piezo, RGB driver after
> curves, ImagePrint, IJC, whatever, is never perfectly linear or
> possibly not appropriate for that given print. So we may have a final
> curve we want to apply to print they way we want today on whatever
> output system we have today. Why would anyone save their file in that
> state? It's device specific. Also, if our work habits are refined, a
> final curve to a high bit file is not very destructive at all. It's
> not an issue.

In theory you are absolutely correct but I think practically data
destruction remains an issue. I know that all adjustments can be made in PS
in 16-bit mode and I have tried working that way. Unfortunately it isn't a
workflow that goes well for me. I do some initial adjustments in 16-bit but
then drop down to 8-bit for all the fine tuning. While I could go back and
apply all my 8-bit adjustments to a 16-bit version of the file the task gets
way too complicated for me and the results don't exactly match.

For instance you have a copy of my print "Side Aisle and Gate." This PS file
has 23 adjustment layers all with different masks. The opacity of many of
those layers was tweaked several times in combination before the print fell
into place for me (or as close as I felt I was going to get it anyways).
Interestingly this pretty much follows how I print in the wet darkroom and
if you look at my printing instructions and charts it is not uncommon to see
10 to 30 different dodging and burning maneuvers with different contrast
filters. I don't recommend or defend this as a good way to print but it
seems to be the way I like to work.

Also I think most people wind up in 8-bit mode for the same reasons they
stick with a "canned" printing software. Ease of use and generally great
results. While adjustments in 8-bit mode do cause data loss it appears you
can lose quite a bit and still get a fine print. Back to the old combed vs.
un-combed histogram discussion.

Anyways my point is that 8-bit image adjustment is widespread and that makes
data loss from poor or over adjustment an issue. So if something like
OPM/IJC increases the margin of error I have working in 8-bit and allows me
to push the data a bit farther before print quality breaks down, I would be
very interested. If it doesn't, then as you say, it is then a matter of ease
or use and convenience which can be a significant factor.

> I'll be willing to bet that, with OPM/IJC and the new Ergosoft option,
> after initial sep curves are developed or canned ones selected, final
> densitometer linearization is an overall correction applied at INPUT
> to the file on the fly. That's exactly the same thing as applying a
> final correction curve, exactly. Any other method of linearization
> would be ridiculously complex and have to alter each and every ink
> channel.
> So, that a file needs some kind of optimization for printing is not a
> plus or minus of any particular product or output system, but more of
> a convenience feature of whether or not it happens on the fly or you
> do it yourself in Photoshop.

Would tweaking the separation curves take things a step further and
genuinely improve output rather than just manipulating the input data as you
explain above?
>
> Black box printing systems-
> Piezo plugin and Pro
> ImagePrint
> Epson driver with RGB cures user can't edit (for experience reasons)
> Maybe some others, I'm not paying much attention at this point
>
> With these, if you have no flat spots, reversals, harsh transitions or
> other major problems, with well made master files a final tweak is not
> a problem. I'd say, for those not interested in delving the depths of
> individual channel control with the new systems, it's no different
> than what an overall linearization is going to do on the fly with
> these new systems. If the correction can be handled by the particular
> percentage points Photoshop offers in a custom grayscale space, you
> can even save it out and apply it when printing on the fly, assuming
> your output system accepts grayscale in.

Your point is well taken. You have certain input data from the scan or
digital capture and the order or manner in which you alter that data from
its initial to final form would seem to be immaterial to the final result.
(Which goes back to the importance of scanning to printing.) Can we be
certain that all paths treat the data in the same manner? Some workflows
such as the RGB separation curves may put much more stress on the integrity
of the file data than some others. Applying the curves to an 8-bit image
file really hashes the histogram which may or may not effect image quality.
Very image dependent.

All in all though the better the monitor and printer profiles you have to
work with the better the results are likely to be, not because one system is
technically better than another but because the way the tools work can have
a great impact on the artistic decisions.

>
> Obviously, new systems have extraordinary features for those who
> choose to work with them and I'm certainly stoked about the
> possibilities. But an output system is not dictating an unwise or
> destructive workflow, it may however make for a much more convenient
> one. Let me know if I'm missing something, please.
> This is worth restating-
> > Of course, as
> > profiles become available for OPM, not only are they canned and
> easy-to-use,
> > the whole thing is free, which is another matter to consider!

I agree! Perfect business model for us end users but the pit fall here is
the same as with the RGB separation methods. We have a nice free open system
but if it was not for the sustained effort of Paul Roark in curve building I
doubt that it would be as popular as it is. Other than yourself, I can't
think of very many other people who contributed to the library of "canned"
curves. If someone does not drive a similar effort with OPM and QuadTone
RIP, I suspect they may not be widely accepted.

Just to touch on a key point again. If a person is printing with as system
of materials, hardware and software, and achieving satisfying results they
should be very reluctant to leave it for the new and untried. The old adage
of, "If it ain't broke, don't fix it." really applies here.

Martin

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Martin Wesley" <
mwesley250@e...> wrote:
...
> In theory you are absolutely correct but I think practically data
> destruction remains an issue.
and bla bla bla <G>... big snip...

I don't think you have to justify your complicated adjustment layers. 
As you say it relates very closely to darkroom work and many fine 
workers do extensive dodging and burning routines. Under these 
circumstances staying high bit can be a pain, and I realize many people 
work in 8 bit.

> Anyways my point is that 8-bit image adjustment is widespread and that makes
> data loss from poor or over adjustment an issue. So if something like
> OPM/IJC increases the margin of error I have working in 8-bit and allows me
> to push the data a bit farther before print quality breaks down, I would be
> very interested.

Well, now I'm really blowing smoke because of my lack of knowledge. How 
that linearization is applied is really the question, and if it's 
primarily the same as a final adjustment curve out, then potential 
destruction is a non-issue in terms of one method over another.

> If it doesn't, then as you say, it is then a matter of ease
> or use and convenience which can be a significant factor.

Absolutely, there are many impressive characteristics of OPM/IJC, and 
if it supported my printers, I'd be all over it.
But here's another major issue we are ignoring. Antonis tells us that 
resizing the file to a friendly dpi is ideal with OPM/IJC, as is high 
bit. If changing to 16 bit then resampling, you will be filling in 
levels and certainly be sending a file with no gaps. Purists would say 
it's non image info, or noise, but I would say it would result in a 
significantly better print than a file with major dropouts in the 
histo. So any internal tonal adjustment done by linearization will no 
doubt be non-destructive, you're working with a lot of levels now. Of 
course you could do the same thing before a final adjustment 
curve out...

> Would tweaking the separation curves take things a step further and
> genuinely improve output rather than just manipulating the input data as you
> explain above?

That's really hard to say. How linearization is applied vrs how seps 
are applied internally would have something to do with it. It's all 
theoretically potentially destructive. I tend to like to make the seps 
as linear as possible so multiple serial adjustment is kept to a 
minimum, but that's based on some bizarre religion instead of science.

...You have certain input data from the scan or
> digital capture and the order or manner in which you alter that data from
> its initial to final form would seem to be immaterial to the final result.
> (Which goes back to the importance of scanning to printing.)
> Can we be
> certain that all paths treat the data in the same manner?


No, some adjustments MAY be being applied in these drivers by defining 
how they ramp, rather than simply applying a curve to an existing file. 
Also, I've found that adjustments applied via a profile conversion 
result in more loss than the exact same adjustments applied manually, 
though the difference may never show in a print.

> Some workflows
> such as the RGB separation curves may put much more stress on the integrity
> of the file data than some others. Applying the curves to an 8-bit image
> file really hashes the histogram which may or may not effect image quality.
> Very image dependent.

Quad ink separation is very severe, no matter where or how it's 
applied. So how all these genius' are addressing that is interesting, 
it all seems to work to 
varying degrees. You can detect stepped output sometimes with some 
systems. I think that just further stresses that our files need to be 
pretty tough to begin with.
I want to add a note about Roy's work with Gimp. My apologies to him 
for not working with it more yet. His final builds are very easy to 
install and use, no terminal work is necessary. The whole thing is very 
ingenious, and he seems to be coming up with some very easy tools to 
create curves.
Time for this dottering quad cadet to go down for a nap.
Tyler

----- Original Message ----- 

From: "Tyler Boley" <tyler@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, June 07, 2003 8:58 AM
Subject: [Digital BW] Re: OPM in theory (to Martin's q.)


> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Martin Wesley" <
> mwesley250@e...> wrote:
> ...
>
> > Anyways my point is that 8-bit image adjustment is widespread and that
makes
> > data loss from poor or over adjustment an issue. So if something like
> > OPM/IJC increases the margin of error I have working in 8-bit and allows
me
> > to push the data a bit farther before print quality breaks down, I would
be
> > very interested.
>
> Well, now I'm really blowing smoke because of my lack of knowledge. How
> that linearization is applied is really the question, and if it's
> primarily the same as a final adjustment curve out, then potential
> destruction is a non-issue in terms of one method over another.

Tyler,

That makes sense. There is no free lunch and the real solution for me lies
in the hands of Adobe and wheither or not they will every provide all of the
current 8-bit functionality in 16-bit mode. I'm not going to hold my breath
on that one.
>
> > If it doesn't, then as you say, it is then a matter of ease
> > or use and convenience which can be a significant factor.
>
> Absolutely, there are many impressive characteristics of OPM/IJC, and
> if it supported my printers, I'd be all over it.
> But here's another major issue we are ignoring. Antonis tells us that
> resizing the file to a friendly dpi is ideal with OPM/IJC, as is high
> bit. If changing to 16 bit then resampling, you will be filling in
> levels and certainly be sending a file with no gaps. Purists would say
> it's non image info, or noise, but I would say it would result in a
> significantly better print than a file with major dropouts in the
> histo. So any internal tonal adjustment done by linearization will no
> doubt be non-destructive, you're working with a lot of levels now. Of
> course you could do the same thing before a final adjustment
> curve out...
Once again I agree. You could avoid data damage from applying final printing
curves by going to 16-bit before using them. This would be interesting to
try with the RGB seperation curve method. I would welcome a program that did
fill in the data in 16-bit during conversion but I suspect that is not what
is happening here. I would bet they are simply right or left justifying the
data. Otherwise the process would be pretty intense because the software
would have to decide which pixels to change from a specific value in 8-bit
to some inbetween value in 16-bit based on adjacent pixel values. That could
be a real nightmare or a blessing if done well.
>
(snip)
>
> ...You have certain input data from the scan or
> > digital capture and the order or manner in which you alter that data
from
> > its initial to final form would seem to be immaterial to the final
result.
> > (Which goes back to the importance of scanning to printing.)
> > Can we be
> > certain that all paths treat the data in the same manner?
>
>
> No, some adjustments MAY be being applied in these drivers by defining
> how they ramp, rather than simply applying a curve to an existing file.
> Also, I've found that adjustments applied via a profile conversion
> result in more loss than the exact same adjustments applied manually,
> though the difference may never show in a print.
>
(snip)
>
> Quad ink separation is very severe, no matter where or how it's
> applied. So how all these genius' are addressing that is interesting,
> it all seems to work to
> varying degrees. You can detect stepped output sometimes with some
> systems. I think that just further stresses that our files need to be
> pretty tough to begin with.

Point well taken.

So in summary it appears that IJC/OPM and QuadTone-RIP don't offer any
absolute improvement in print quality over other earlier methods. However,
they may allow the user to reach the ultimate quality level of their
printer, ink and paper more easily, which for a given user may result in a
significant improvement in their own print quality. I think both of these
programs are key advances in that they do offer the user access to
individual channel control if desired, their low cost (or no cost) and open
system model is the direction most beneficial to end users. I hope that we
will see more info on these systems as they mature.

Martin