New Approach for Generating Optimal Profile Patch Sets

[Alan Goldhammer]

Doug, your ABW approach will only work with Windows OS as anyone on a MAC cannot use ABW profiles.  This pathway was broken by Apple at least five years ago and I remember Eric Chan complaining about it at the time.

[rasworth]

Doug,

I created a 1000 patch set (fills up 13"x19" for i1Pro) using -m 8 -l 4 -n 86 with neutrals training from previous profile.  It seems to me your new version causes the near neutrals to hug the L* axis more closely (plot attached).  Is this controlled by the -s parameter?

Richard Southworth

[Doug Gray]

Doug,

I created a 1000 patch set (fills up 13"x19" for i1Pro) using -m 8 -l 4 -n 86 with neutrals training from previous profile.  It seems to me your new version causes the near neutrals to hug the L* axis more closely (plot attached).  Is this controlled by the -s parameter?

Richard Southworth

Yes, I changed the default "-s" parameter to 2. You can modify it. If you set it to 0 it will follow the actual neutrals but the value of 2 gives it a small amount of variation which might help is some instances. If you examine the CGATs file, the full set of options used is stored in the description tag like this:

Opts:t0f0r0v0 m8M1l3L1h0H1s0n76C1 iprofilename A bit cryptic but each letter is followed by the value and the bools are either 1, if selected, or 0 if not.

[Doug Gray]

Doug, your ABW approach will only work with Windows OS as anyone on a MAC cannot use ABW profiles.  This pathway was broken by Apple at least five years ago and I remember Eric Chan complaining about it at the time.

Well, ABW is a lonely orphan. OTOH, my code, while in portable C++, is only compiled for Windows. I could compile it for iOS but I'd have to buy an Apple. Eventually I'll post the source to GitHub and someone with iOS could compile it. That wouldn't solve the ABW of course but would make the patch generation program available to Apple users. 

Or one could borrow someone's PC. 

[Doug Gray]

Hot Dog!

On the 9800, I created a patch set for ABW using the idea mentioned above, saved the RGBLAB CGATs file with a full 256 measured device neutrals using ABW and I1Profiler happily made a profile.

What's even better is that, after printing the 256 patch set assigned to ProPhoto using the profile and selecting Abs. Col, all the in-gamut L*s variances were incredibly close to 0. Average dE 1976 was .11 dE00 was .09

Unreal. And even better. the DMax dropped. Min. L* went from 4.0 to 2.9.

I now have a great profile for printing using normal color management with ABW!

[Alan Goldhammer]

Hot Dog!

On the 9800, I created a patch set for ABW using the idea mentioned above, saved the RGBLAB CGATs file with a full 256 measured device neutrals using ABW and I1Profiler happily made a profile.

What's even better is that, after printing the 256 patch set assigned to ProPhoto using the profile and selecting Abs. Col, all the in-gamut L*s variances were incredibly close to 0. Average dE 1976 was .11 dE00 was .09

Unreal. And even better. the DMax dropped. Min. L* went from 4.0 to 2.9.

I now have a great profile for printing using normal color management with ABW!

Excellent work.  My 3880 bit the dust last week and I have a new Canon Pro-1000 sitting in the box as I need to wait for my neighbor to help get it up on the printer table.  I'm interested toe explore how it handles B/W printing as I still do a fair amount of that and have scanned a lot of old Tri-Ex negatives.

[1PhotoGuyinNM]

Hi Doug,

I really appreciate you sharing your observations and work.  Now that you appear to be converging on an optimal approach, would it be possible for you to create a document which summarizes the process and provides recommended values (or possible starting points) for profile creation using the tools and techniques that you developed?  I am sure it would be extremely useful to the entire community and would help simplify the process. Thanks!

[Doug Gray]

Hi Doug,

I really appreciate you sharing your observations and work.  Now that you appear to be converging on an optimal approach, would it be possible for you to create a document which summarizes the process and provides recommended values (or possible starting points) for profile creation using the tools and techniques that you developed?  I am sure it would be extremely useful to the entire community and would help simplify the process. Thanks!

I'm currently working on adding ABW to the program. Being able to use softproofing and get consistent B&W prints using ABW is badly needed for ABW users getting by in Photoshop.

So the main value of the program is to generate profiles that produce more accurate neutral and near neutral colors for regular color printing and do so with smaller patch totals. The secondary benefit is providing profiles for use in ABW printing.

But after the program is more finished I do intend to write a pdf description and outline the various usages.

[JRSmit]

Here's the latest (Ver .4). It's a 32 bit Windows program so works in both x64 and x86 Windows.

I've added options to generate high density subgrids in low and high RGB values. This is mostly useful for generating more accurate patch sets for images with larger, darker areas.

I've attached a sample, agnostic patch set with a 10x10x10 main grid and 6x6x6, low RGB value high density grid. The high density grid is repeated because the elements are close and this reduces variation in patches.

These are the options for the command line operation but it also works in interactive mode..

Usage: ICCProfilePatches [-f] [-t] [-r repeats] [-p pagesize] [-m MGrid]\n                  "
                        [-s StaggeredNeutralDistance] [-n neutralCnt] [-i iccProfile]\n"
                        [-C ColorimetricMode] [-c creator] [-o outfile]\n";

     -t                   Test run. Don't create output. Use to get statistics\n"
     -f                   Emit fractional RGB values, ints are default\n"
     -r                   Remove neutrals in grids (use when adding neutrals separately)\n"
     -v                   Scramble Patches\n"
     -m MajorGridDim      Major Grid dimension\n"
     -M repeatcount       Major Grid Repeat Count\n"
     -l LowGridDim        Low Grid Dimension (scales and places half spacing packed grid at low RGB values)\n"
     -L repeatcount       Low Grid Repeat Count\n"
     -h HighGridDim       High Grid Dimension (scales and places half spacing packed grid at high RGB values)\n"
     -H repeatcount       High Grid Repeat Count\n"
     -s staggerVal        Stagger alternate RGB neutrals by this magnitude\n"
     -n Counts            Counts neutrals (device or colorimetric) are added\n"
     -C Color mode        1 (Colorimetric) or 3 (Absolute Colorimetric)\n"
     -o CGATsFilename     The name of the CGATs file\n"
     -i ICC profile       Profile used to adapt neutrals to actuals\n"
     -c creator           Who dunnit\n";

Hi Doug,

Your downloads are not accessible , has something changed?

[Doug Gray]

Hi Doug,

Your downloads are not accessible , has something changed?

No idea. Seems to not be on the server anymore. odd.

[Alan Goldhammer]

No idea. Seems to not be on the server anymore. odd.

There are also some threads that disappeared yesterday on some of the other sections.  I would ask the senior Moderator, Jeremy Roussak, what has happened (he won't talk to me).

[JRSmit]

No idea. Seems to not be on the server anymore. odd.

Too bad, hopefully will become available soon. Tested the previous version, did give a smoother result in the a and b curves from black to white. Withe exception of near blak and near white, on these areas there is a issue. That is why i am hoping on your latest version as it addresses those RGB value areas.

[Alan Goldhammer]

Doug, did you run the Canon printer calibration for the media setting before printing out profile targets?  I just got my Pro-1000 set up this morning and before I start to go wild profiling papers it would be good to know how crucial a step this is.

[Doug Gray]

Doug, did you run the Canon printer calibration for the media setting before printing out profile targets?  I just got my Pro-1000 set up this morning and before I start to go wild profiling papers it would be good to know how crucial a step this is.

When I first set up the printer I ran the installation instructions which clearly includes some sort of initial calibration. I printed profile patches for reference. I then ran a calibration on Canon Plat. Gloss. It slightly reduced gamut and the patches varied so I cleared it back to the installation default. So all testing since has been with that native installation/calibration.

I think that's the best way to go for people that make their own profiles. I do like the idea of Canon's individual printer calibration where one is importing profiles and it should reduce printer to printer variation. But I don't think the approach is as good as directly profiling a printer.

[Alan Goldhammer]

Yes, it does a required alignment/calibration when you first set the printer up.  The printer documentation is really not clear on the usefulness of the media calibration process and I thought the same as you, that one's profile would address all the color management issues.  I've heard that if you do a calibration and prepare a profile, that profile can be used reliably on someone else's calibrated printer.  That's not my concern.  I just didn't want to print out lots of targets and do profiling and then find out that it was not the optimal way to go.

[Doug Gray]

Yes, it does a required alignment/calibration when you first set the printer up.  The printer documentation is really not clear on the usefulness of the media calibration process and I thought the same as you, that one's profile would address all the color management issues.  I've heard that if you do a calibration and prepare a profile, that profile can be used reliably on someone else's calibrated printer.  That's not my concern.  I just didn't want to print out lots of targets and do profiling and then find out that it was not the optimal way to go.

Yep, A really good technical approach to dealing with aging as well as inter printer compatibility with vendor profiles. Poorly documented though. Especially interactions between calibrations and paper types affected. Could be useful but I'd have to do a lot of experiments to see what works and what doesn't. Not worth the time unless I had multiple printers where it might be handy to use the same profile for each.

[Doug Gray]

WARNING!

I have recently discovered a peculiarity of I1Profiler when using lots of neutrals/near neutrals. And it's greatly magnified when used with smaller numbers of color patches.

This can produce, in some cases, wildly wrong profiles. I have seen profiles with huge variations along the neutral axis. Not often but sometimes.

I strongly recommend setting the "Smoother"slider at 80 instead of the default, 50, when using profiles with lots of added neutrals/near neutrals.

I'm currently working on finding the best settings by making profiles with these settings but for now, be aware of this potential problem.

[rasworth]

Doug,

This combo (attached) of 256 neutrals/near neutrals and 6 colors went thru ok, with smoothness set to 50.  How does "wildly wrong" manifest itself?  Do we look for bad neutrals in a test print?  Is there a quick check in ColorThink Pro?

Richard Southworth

[Doug Gray]

Doug,

This combo (attached) of 256 neutrals/near neutrals and 6 colors went thru ok, with smoothness set to 50.  How does "wildly wrong" manifest itself?  Do we look for bad neutrals in a test print?  Is there a quick check in ColorThink Pro?

Richard Southworth

Richard,

I've seen profile errors just along the neutral axis of over 10 dE. Rare though. When it occurs it sees to be most often when the stagger value is 0 or near 0. Virtually goes away with the smoothness slider set to 80. It's really strange and difficult to pin down because it's so infrequent.

However, it disturbs me to see this sort of thing at all. Suggests some weird stuff going on in I1Profiler. Almost like some matrixes that were being inverted for curve fitting had near singular Eigenvalues. When this happens math errors can go through the roof. Since it takes a fair amount of work to detect this and strip out the near singular results it may be the cause. But this is rank speculation based on my own experience with DSP work. So I'm testing their program by introducing step functions in the neutral response and looking at how the smoothing setting interacts with it. It would be way faster if they had a batch processing capability like ProfileMaker 5.

In the meantime I suggest setting the smoothness slider at 80.

My gold standard is to print, and scan the LAB neutrals in steps of 1 and plot the results. This is time consuming. Right now testing an idea has a turnaround time of about 10 minutes. However, the magnitude of the errors, when they occur, are easily seen in my Matlab tools.

This is sort of fun, I like problems. Especially unexpected ones. Makes me want to dig and find out what's going on.

[rasworth]

Doug,

As an EE (retired) I do remember eigenvalues and singularities, although it's been a while.

Thanks for the alert,

Richard Southworth