Gordon-
When I move a printed press sheet from our pressroom standard D50 lighting to office lighting there is a perceptual change in the color of the imagery on the sheet. When I move an Epson proof produced with K3 inks from our pressroom standard D50 lighting to office lighting there is little perceptual change. When I move an Epson proof produced with pre-K3 inks from our pressroom standard D50 lighting to office lighting there is a significant perceptual change in the imagery on the sheet. Would I not be correct in stating that the Epson produced with K3 inks is more color constant(using the definition of said Color Constancy) than the press sheet or the Epson produced with pre-K3 inks. Epson clearly addressed this when they produced the K3 inkset,
and I am wondering why offset ink companies don't address this, or even attempt to address this. I know there are variables(UV brighteners, etc.) that also play a part, but I find it hard to believe that nothing can be done.
Regards,
Todd
No, I don't believe this has anything to do with "color constancy."
Color constancy is the eye/brain determining the approximate wavelength composition of light striking the observed object and then discounting that part of the illumination in order to obtain the "true" color of the object. Basically, a white paper looks white, or a red apple looks red, under a variety of lighting conditions.
What you're referring to is the effect of the spectral composition of K3 inks vs other inks. You are evaluating how one set of pigments reflect light compared to a different set of pigments under the same illuminant.
I.e. You're taking proof K3 and proof X and comparing them under illuminant D50 and under D32. One appears to shift more than the other. So what you are experiencing is illuminant metameric failure.
If you weren't making a comparison then you might be able to say that the color of the K3 proof does not appear to shift as you go from one illuminant to another. In that sense you might be able to say that color constancy is a factor in why the color doesn't appear to shift under different illuminants.
However when you are comparing, for example, two or more proofs to each other or to a press sheet you are in the realm of metameric pairs. If the proofing pigments were identical to the offset press pigments then you would expect a metameric match under every lighting condition. Since that's unlikely, then you would hope for them to be metameric pairs. I.e. match under one, or more, specific lighting conditions.
So, you're asking for inkjet manufacturers to use pigments that have a much closer spectral composition to the pigments use for presswork. That way proof and presswork would continue to match under different lighting conditions. That being said, the white paper of the proof and the white paper of the press sheet will always appear white because of color constancy.
Sorry if this is too pedantic.
best, gordon p