Is possible to add option to use Black Point Compensation in color convertion and Color Management settings?
I am working to give professional tools about Color to CorelDRAW users.
I teached about color conversion last week and I showed how close CorelDRAW can convert colors when compared with Photoshop.
But, there is one tool that has a huge difference, and it is Black Point Compensation.
This could be addressed to implement?
Black Point Compensation is not supported by CorelDRAW, nor Photo-PAINT. It is a non-ICC complaint workflow developed by Adobe to compensate for malformed RGB color spaces over 2 decades ago. BPC only works with relative colorimetric rendering and modifies it in a matter that (in layman's terms) mimics perceptual rendering. BPC was needed many years ago to establish a proper source and destination black point for the bad profiles of the past and has had no relevance for nearly 2 decades. Perceptual rendering is the default rendering used for all non device specific color profiles I've seen for nearly 20 years.
Simply set all applications Corel, Adobe or what ever to use perceptual rendering. CorelDRAW supports more color engines than Adobe does, I cannot find out what color engine Affinity uses, in any case my suggested settings will provide conversions as close as possible between the applications.
Some CorelDRAW users like the LCMS (little color management system) engine I prefer WCS (Windows Color System).
Thank for weel explained answer.
But, when we use perceptual we have all color changed, when we use colorimetric, all colors inside gamut is not changed (transformed), am I right?
How Relative and Absolute Colorimetric is used to have contratual proofs for impression, if I use perceptual, I have a different aproach to this situation and I do not get my proposal to have transformed only color out of gamut.
Am I right?
First things first, I have my grandchildren here today and tomorrow so my (sane) time is limited. I'll give a rough overview then in the next few days get you some documentation.
I'm not sure what your native language is and I only have the definitions in U.S. English. I must admit even if English is your native language most people need to read the definitions several times and then still need help understanding them.
There are 4 rendering intents:
Saturation (I have never seen a workflow where it was valid) does as it says it over saturates the conversions.
Absolute Colorimetric, used for hard proofing, it does well if proofing a newsprint job on gloss or matte paper. It will always try and print a gray color to simulate the white point of the destination, ergo the prints always have a frame around them to simulate the destination paper.
Perceptual rendering, the only profile created for converting large color spaces into small color spaces. Such as Prophoto RGB to Adobe or sRGB, or any RGB color space to any CMYK color space.
Perceptual is the default rendering intent for almost all ICC profiles that are not device dependent print color profiles. Yes the colors change but all colors in the source are represented in the destination in a proportional manner so the result looks as much like the original as possible for the destination gamut. Yes out of gamut colors change but they rarely posterize.
Relative Colorimetric rendering is really only good at converting color spaces of very near or equal sizes. It has no value for converting wide gamut spaces into small gamut spaces.
No relative colorimetric does not leave unchanged source colors that are in gamut in the destination space. Mathematical changes do take place differently for source colors that are in gamut for the destination space then for source colors that are out of gamut for the destination space. THAT'S the PROBLEM. In wide gamut to small gamut conversions a very few colors get little change and a very large amount of colors get a radical change. Causing distortion and posterization.
Many RGB color spaces are vastly larger then CMYK color spaces, Prophoto RGB is so much larger than sRGB that conversion to sRGB from Prophoto in many cases using relative colorimetric causes severe distortion and posterization.
The above rendering intents ARE ICC COMPLIANT! The below discussion is not ICC Compliant.
Relative Colorimetric with Black Point Compensation turned on IS NOT ICC COMPLIANT!
Black Point Compensation turned on only works with Relative Colorimetric Rendering by design. It mimics Perceptual Rendering but it very slightly different.
Do a test! Take a colorful RGB image and duplicate it twice. Convert all three images to the same CMYK profile one with perceptual rendering, the nest with Relative colorimetric with black point compensation TURNED ON, then convert the third image with Relative colorimetric with black point compensation TURNED OFF and compare them in Photo-PAINT simultaneously.
There are two basic errors made in the default installations by Adobe and Corel.
Adobe should have stopped using relative colorimetric rendering with black point compensation turned on 20 years ago. It has not been needed for that long.
When Corel changed to a professional color management process with the release of version X5 they should not have had relative colorimetric rendering with black point compensation turned off as their set default.
Both applications should default to perceptual rendering.
Adobe has made cross application color management difficult because they support very few, to only their color engine and they stopped releasing a 64 bit version of Adobe Color Engine (ACE) for others to use. To ad insult to injury their steadfast use of relative colorimetric rendering with black point compensation turned on.
Corel at least supports multiple color engines, although they need to set their default to perceptual rendering.
Now that the grandchildren are gone and sanity is returning I took the time to update my reading of the ICC (International Color Consortium) specifications and white papers. I have downloaded pertinent content and will place on line for you to download if you wish.
The truth is that reading all that data is as complicated and confusing as the Unabomers Manifesto. Confusing logic to say the least.
Color management while being an evolving technology is has been significantly mature for well over a decade.
I find it best to keep discussions sectioned into three major categories. Those who calibrate manufacturing devices. Those who are high end color critical work creators. Those who simply need basic settings for specific tasks.
For those like me who calibrate equipment the software and specifications have improved for greater accuracy. However, the question as always is, has it exceeded demand and general capability?
I regularly see the physical aspects of calibration being ignored so often that the reality is that with all the software improvements there is no real-world improvement.