CHROMiX

fishing with a net

Hiya,

I just learned the value of a color list. Plotting all of the points in 3D is truly a great way of visualizing the statement, “You can’t get there from here!” My next ambition is to load a color list and an output profile (ie 7600 Proofing semimatte 720 PK), show how many colors are in gamut, and pinpoint which on the color list are out of gamut. Can the color list be sorted by in gamut/out gamut? Could this be done with and Xcel spreadsheet?

Needless to say, a picture is worth a thousand words and thanks to Colorthink that picture is in the round!

At 3:25 PM -0700 4/27/05, mikkelpope wrote:

Hiya,

I just learned the value of a color list. Plotting all of the points in 3D is truly a great way of visualizing the statement, “You can’t get there from here!” My next ambition is to load a color list and an output profile (ie 7600 Proofing semimatte 720 PK), show how many colors are in gamut, and pinpoint which on the color list are out of gamut. Can the color list be sorted by in gamut/out gamut? Could this be done with and Xcel spreadsheet?

not at this time. That is a feature that will be available in the upcoming ColorThink Pro. Calculating a gamut boundary and marking colors as in our out of gamut can be a bit involved. Strange considering that when you graph it it is fairly obvious.

Needless to say, a picture is worth a thousand words and thanks to Colorthink that picture is in the round!

glad you like it!

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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Good Stuff,

For now I can use Xkey, 530 and Excel, measure spot colors, save a text file, load the list and profile and see how much the gamut can capture. I was thinking of something like the layer palette in say photoshop where you click on the eye to reveal/hide content.

I look forward to the new release.

:^)

Matt

At 3:38 PM -0700 5/2/05, mikkelpope wrote:

Good Stuff,

For now I can use Xkey, 530 and Excel, measure spot colors, save a text file, load the list and profile and see how much the gamut can capture. I was thinking of something like the layer palette in say photoshop where you click on the eye to reveal/hide content.

ok… I think you’ve lost me here… where would this be? You can plot or not plot items by checking them but I think you mean something else…

I look forward to the new release.

me too!

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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To clarify my process, I measure a swatch with an Xrite 530 and use Xkey to bring the data into excel. I then turn the excel list into a color list in Color think. With the color list loaded, I will also load a few output profiles to see where the color list lands in relation to the device gamut.

If I could load a color list and each color could be hidden/revealed like layers in Photoshop that would be super. I can pretty much do this now by having a color list with only one color then reveal/hide that list. Some color lists I build have dozens of colors.

At 1:39 PM -0700 5/27/05, mikkelpope wrote:

To clarify my process, I measure a swatch with an Xrite 530 and use Xkey to bring the data into excel. I then turn the excel list into a color list in Color think. With the color list loaded, I will also load a few output profiles to see where the color list lands in relation to the device gamut.

If I could load a color list and each color could be hidden/revealed like layers in Photoshop that would be super. I can pretty much do this now by having a color list with only one color then reveal/hide that list. Some color lists I build have dozens of colors.

Ah… OK, now I get it…

the UI in the Grapher is not detailed enough to allow color-by-color selection within a list. So now you use a different list for each color - which is also a pain…

Pro will allow something like this but I’m not sure it’s exactly what you want. It will allow the highlighting of colors within a list (the color in the graph is marked so you can tell it from others) It doesn’t yet allow showing or hiding of one / many though… I think about how this might be done.

The whole act of selecting colors from images / lists gets rather complex and I insist on making the UI as clean and intuitive as possible. That said, I’m sure there’s a solution in here somewhere… Sorry you can’t see Pro yet… no one wants it to be released more than I!

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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I like this software more and more, I keep finding more uses and valuable feedback about profiles and the colors then define.

I’ve been selecting individual colors in a color list and doing so on my XP machine sometimes creates an infinite loop in the Plot Item palette, my attempts to recover from the loop crash Color Think. On the mac I can drag a color from the color list to the Plot list and that works fine.

On another note, is it possible to take a CMYK image using a refrence profile like SWOPv2 into Lab and then back out to an inkjet profile and use Color Think to reveal what the CMYK build is?

Are you using version 2.1.2? I believe this looping bug is fixed in the latest beta, which is a free download for curent users.

At 8:10 PM -0700 7/7/05, mikkelpope wrote:

I like this software more and more, I keep finding more uses and valuable feedback about profiles and the colors then define.

glad you like it. I’m also glad you are taking the time to explore color using it.

I’ve been selecting individual colors in a color list and doing so on my XP machine sometimes creates an infinite loop in the Plot Item palette, my attempts to recover from the loop crash Color Think. On the mac I can drag a color from the color list to the Plot list and that works fine.

are you trying this on the most recent beta? (b15). If so we’ll work at reproducing it here and killing it…

On another note, is it possible to take a CMYK image using a refrence profile like SWOPv2 into Lab and then back out to an inkjet profile and use Color Think to reveal what the CMYK build is?

ColorThink Pro will do a better (easier) job of this but it’s not shipping yet (soon, really, honestly…)

But, you can do it in the current version using color lists rather than images.

Follow these steps:

  • open a CMYK data file (there are a couple in the “stunt files” folder)
  • drop (or open) your SWOP profile onto the color list and CCT will generate Lab
  • you might want to change the intent to rel col here…
  • choose file:save as… and save the Lab data to disk
  • open the Lab file into ColorThink again
  • drop your inkjet profile onto the list and select your desired intent
  • then you will see the CMYK inkjet build that results from the original SWOP CMYK.

A bit convoluted but it works.

The Lab file is a pretty good reference file for various tests as it is now a bunch of in-gamut SWOP colors.

You can also load the Lab color into the grapher and plot as vectors using the Inkjet profile as the destination. Then you will see the color shifts introduced into the SWOP color by the inkjet profile.

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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Thanks guys,

The beta update works and resolves my earlier issue with the loop in the plot list. I like the workflow for the SWOP and inkjet profile, it is simpler than getting Profiler data into Profile Maker.

One question, if I load an IT8 refernce file (from PM 415) as a ColorList then apply a profile like SWOPv2 I get Lab numbers, great, I need those for a project I’m working. But when I change the rendering intent Lab values are unchanged. If I print an image and change the rendering intents the color changes, so by that reasoning shouldn’t the Lab values in my Colorlist change too?

Thanks for all the thourough replies to date.

At 11:54 AM -0700 7/13/05, mikkelpope wrote:

Thanks guys,

The beta update works and resolves my earlier issue with the loop in the plot list. I like the workflow for the SWOP and inkjet profile, it is simpler than getting Profiler data into Profile Maker.

One question, if I load an IT8 refernce file (from PM 415) as a ColorList then apply a profile like SWOPv2 I get Lab numbers, great, I need those for a project I’m working. But when I change the rendering intent Lab values are unchanged.

Good question.

First I would suggest trying it with a different profile. Preferably one that isn’t a “stock” profile. I think you will see a difference between the intents.

Profiles are required to have ‘entries’ for each rendering intent from CMYK->Lab (there are 3 intents - perceptual, saturation and colorimetric - relative and absolute each use the same table w/ different math). Each of these entries is actually in a tag table of contents. It is perfectly legal to have all of the entries point to exactly the same LUT table in the profile so that no matter which intent you choose, you get the same table and hence the same results.

I think you are running into one of these situations. If you open the profile into the Profile Inspector and look at the Tag Table tab you will see the different A2Bn entries listed. If any of them are italic text then they are sharing the table with another intent. Check the offset values that ColorThink reports for each tag to see which ones are sharing the same LUT table…

If I print an image and change the rendering intents the color changes, so by that reasoning shouldn’t the Lab values in my Colorlist change too?

another good question.

When you print an image you are applying two different profiles and receiving different intents from each profile. So lets use the example of printing an sRGB image to a CMYK SWOP profile and choosing the perceptual intent. The CMS (typically Photoshop) will attempt to use the perceptual RGB->Lab intent from the sRGB profile and the perceptual Lab->CMYK intent from the SWOP profile.

Two important things to note about this are:

  • there is no such thing as a perceptual intent of any sort for the sRGB profile as it is a matrix profile and they have no such tables. You get colorimetric from them no matter what you ask for.

  • the Lab->CMYK transform chosen from the SWOP profile is a totally different table (and direction) than the one you are testing in your original CMYK->Lab question.

Hope this helps…

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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Hi Steve,

This indeed answers my question. I have a test that I’d like to run by you.

  1. I open the ECI 2002V as a colorlist - it’s populated with CMYK values
  2. In the Colorlist I assign Adobe’s SWOPv2 and populate the Lab values and save the list with Lab, Xyz and Device Color.
  3. I open this second generation list and assign it Adobe’s SWOPv2

Now when I change the rendering intents the CMYK builds shift drastically and if I select the AbCol intent the CMYK numbers match the first generation color list. Does this verify that my first generation list got populated with Lab values using the AbCol rendering intent? Does this round trip even make sense?

My final goal is to use a profile optimization utility on an Inkjet RIP and our customer wants to reference Adobe’s SWOPv2. But I have no physical target to measure and iterate against, this is why I’m trying to use Colorthink to extract the Lab data for iterations.

By the way, does anyone know what press created Adobe’s SWOPv2 or was that put together in a mathmatical program.

Thanks for the insights thus far.

Steve,

This reminds me of what I thought was a really cool idea for the 2.0 Beta, namely the ability, when plotting a 3D image file gamut versus a profile gamut, to be able to click on image cubelets (or spheres or whatever) with something like an eye-dropper, and get a reading in Lab (or whatever the colour space was) of what colours are represented by a given cubelet, and so find out what colours in the original image are out of gamut.

I suspect that this feature is a lot easier to describe than to program! :slight_smile:

Regards,

Alan

At 4:45 PM -0700 7/26/05, mikkelpope wrote:

Hi Steve,

This indeed answers my question. I have a test that I’d like to run by you.

  1. I open the ECI 2002V as a colorlist - it’s populated with CMYK values
  2. In the Colorlist I assign Adobe’s SWOPv2 and populate the Lab values and save the list with Lab, Xyz and Device Color.
  3. I open this second generation list and assign it Adobe’s SWOPv2

Now when I change the rendering intents the CMYK builds shift drastically

good

and if I select the AbCol intent the CMYK numbers match the first generation color list. Does this verify that my first generation list got populated with Lab values using the AbCol rendering intent?

pretty much yes. AbsCol both ways should get you fairly close.

Does this round trip even make sense?

indeed.

My final goal is to use a profile optimization utility on an Inkjet RIP and our customer wants to reference Adobe’s SWOPv2. But I have no physical target to measure and iterate against, this is why I’m trying to use Colorthink to extract the Lab data for iterations.

understood. And yes, these calculating numbers this way should work fine. As you mentioned, AbsCol is the way to go so paper white is in there.

By the way, does anyone know what press created Adobe’s SWOPv2 or was that put together in a mathmatical program.

As far as I know it was created from the TR001 dataset. You may want to go straight to the horses mouth on this and order the TR001 set from NPES.org

Thanks for the insights thus far.

no problemo

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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At 5:42 AM -0700 7/27/05, alanrew wrote:

[quote:03c7bd0c2a=“upton at chromix.com”]
wrote:Calculating a gamut boundary and marking colors as in our out of gamut can be a bit involved. Strange considering that when you graph it it is fairly obvious.

[/quote:03c7bd0c2a]

Steve,

This reminds me of what I thought was a really cool idea for the 2.0 Beta, namely the ability, when plotting a 3D image file gamut versus a profile gamut, to be able to click on image cubelets (or spheres or whatever) with something like an eye-dropper, and get a reading in Lab (or whatever the colour space was) of what colours are represented by a given cubelet, and so find out what colours in the original image are out of gamut.

yup, I’ve certainly though of that one…

I suspect that this feature is a lot easier to describe than to program! :slight_smile:

yes, the toughest part is “picking” a 3D point out of thousands of possible points. There are routines available in OpenGL to help but when it’s thousands of colors it gets either very complicated or very slow…

I’m working on it though…

Regards,

Steve


o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX


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