Hi Lou, I think there's a pretty simple explanation of what you see. When you run Convert-To-Profile you get to select Intent & BPC so that overrides anything you selected in Color Settings... Looking at the Info Palette after conversion for the RGB values will be giving you exactly what's in the file. You see they are all the same which makes sense since the conversions were all the same. But looking at the LAB values in the Info Palette will have to run though Color Conversion again. (whenever you look at Info: a CM operation is done for all formats except the real file format). So the RGB -to- LAB conversion is the print-profile to Lab using the default i.e. Color Settings... selections of Intent & BPC. This Info Palette color conversion issue shows up all the time with RGB vs grayscale K - values. You have to realize that only the matching format shows what's in the file. The other one shows a CM conversion to the corresponding working space that you set in Color Settings... Roy On Wed, Sep 10, 2014 at 1:35 PM, Louis Dina <lou@loudina.com> wrote:
I have been through this before a number of years ago, but want to be sure I have this clear in my mind.
I took a wide gamut RGB target with very saturated colors and brought it into Photoshop. It was untagged, so I tagged it with ProPhoto RGB to give me the widest possible gamut and the most saturated Lab numbers. Then, I converted it in PS to a high gamut RGB printer profile (glossy RC paper on an Epson 3880). I used Relative Colorimetric with BPC for all the following conversions.
Before converting from ProPhoto RGB to the destination printer profile, I altered my Conversion Options in the PS Color Settings dialog box.
1. The first conversion from ProPhoto RGB was done with Color Settings Conversion Options set to Abs Colorimetric and BPC turned Off.
2. The second conversion from ProPhoto RGB was done with Color Settings Conversion Options set to Rel Colorimetric and BPC turned Off.
3. The third time, my conversion from ProPhoto RGB was done with Color Settings Conversion Options set to Rel Colorimetric with BPC turned On.
The actual conversion was done from Edit > Convert to Profile > Rel Col and BPC.
In each case, the Info Palette shows that the RGB numbers are identical, regardless of Color Settings Conversion Options. However, the Lab readout in the Info Palette is different for each conversion.
So, if conversion options is set to AbsCol w/o BPC, I am assuming the Lab readout is showing what the actual Lab numbers would in the dried print if I read the print with my spectro (assuming a perfect conversion, of course). Is that correct?
Assuming that is correct, I'm a little less clear on why I get different Lab numbers when Color Settings have RelCol Conversion Options, one with BPC turn On and one with BPC turned Off. In both these cases, white shows up 100L/0a/0b, which I feel confident is the color of paper white (which is less than 100/0/0). What surprised me, however, was that Black was different, one reading 7L/0a/0b, and the other reading 1L/0a/0b. I would have thought they'd be the same.
I could use some clarification.
Also, which Conversion Option makes the most sense to leave as the default setting in Color Settings?
Thanks,
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