"brian0918" wrote in message
I want to adjust the colors in this image so that the color labeled "Red" is red, "Blue" is blue, etc:
http://memory.loc.gov/service/pnp/cp…0/3g04814r.jpg
(I have a larger version of the image that I am using, but you get the idea)
There is probably a really easy way to do this; I just haven’t found it.
In theory, you can accomplish this via info points on the relevant colors. Set them to HSB mode, and use curves to adjust them to the appropriate hue angles, zero for red, 240 for blue, etc. This will probably be of limited usefulness because the hues of the patches are probably not accurately known.
You may get more accuracy by getting nominal Lab values for the control patches, and using curves to match them as best you can. This is called color pinning in Curvemeister, and can be used to good effect, provided you are aware of the limitations. If Kodak does not publish these values, perhaps you can use a spectrophotometer to measure the Lab color values of the original card, if it is available. Focus on an accurate match for the light red, red, and light blue patches, since these are the colors that appear in the image.
A lot can be done without having accurate Lab values for the patches. I would use curves (what else?) to remove the overall yellow-green cast from the image, make sure that black and white colors span the entire range, and use a gradient layer mask and an adjustment layer to correct the uneven lighting of the original.
Since this appears to be a hand tinted engraving, or color block print, I would not concern myself so much with color fidelity, as with having a reasonably natural skin tone, and a brighter look to the colors. The original artist was, after all, not able to achieve an accurate rendering of the subject, since he was limited by whatever pigments were used for the original colors.
—
Mike Russell
www.curvemeister.com/forum/
