Metamerism and custom output profiles

Hi,

I make custom paper profiles and I'm wondering how the profiling software

interprets the metamerism characteristics of different printers, or if it does.

When I create a profile I usually set the viewing light source to D65 (6500k).

So I believe that the profile software (Profile Maker) makes the print a little

more yellow to compensate for the cool lighting. When I soft-proof in Photoshop

the image takes on a yellow cast. So how does my profile software know if I'm

using an older 9600, which I am, or a newer 9800 which has much better

metamerism prevention(or so they claim). I don't believe the software knows

what printer type I have, nor does it ask.

Thanks

The characteristics of the printer are incorporated into the profile. It's not necessary for the software (e.g., Photoshop) to know the particular printer as long as the profile shows how that printer responds. Soft proofing essentially reads the profile in reverse, showing the gamut and contrast limitations.

Metamerism occurs because the reflectance of the dyes used in a print is not constant thoughout the band width. Consequently, the print will look different when the distribution of the light changes. Your eye is forgiving under changing conditions, possibly because your brain takes cues from what should be "white", "grey" or of a known color (e.g., grass green).

It doesn't account for metamerism. The colour values in the target that are read by the spectro are compared to what the values should be in a data file. A set of differences or corrections is recorded which essentially becomes the profile. The RGB values are converted to LAB values with the proper corrections when the file is sent to the printer.

The profiling hardware/software doesn't discern what printer is being used. All it does is read the RGB values of the target that gets printed. That's all it needs to do.

Does the yellow cast appear when you print or only when you soft proof? Have you looked at the soft proof with both Simulate Paper White turned off and turned on and is there a difference that might be accounted for by a slight warmness of the paper? Have you tried creating the profiles with the light source set to 5000K which is the more common approach to profiling?

I think its worth pointing out what Metamerism is:

Two (2) samples with different spectral properties compared to each other with a

given set of viewing conditions equals Metamerism. Metamerism is good!

One (1) sample compared to itself in differing viewing conditions:

Color Constancy (or inconsistency if there's a change).

For metamerism:

Match Metamerism

Mismatch (no standardized term)

For constancy

Match Constancy

Mismatch Inconstancy

The lack of a defined term for the metameric mismatch is the problem.

"Metameric failure" is the best so far because it is unambiguous.

<p>A colorimeter would indeed not be able to measure metamerism, since it determines

color measurements and matches assuming a single light source (D50 or D65).</p>

<p>But if soft-proofing creates a yellow cast, <em>shouldn't you then make color

adjustments as you're soft-proofing to correct the color of the soft-proof?</em></p>

Thanks for all the responses.

"But if soft-proofing creates a yellow cast, shouldn't you then make color adjustments as you're soft-proofing to correct the color of the soft-proof?"

But shouldn't profiling my paper eliminate the need to make color adjustments. I'm concerned that this yellow cast is a problem.(maybe user error on my part in making the profile?) I had assumed that since I was profiling for D65, that maybe the yellow cast was intended to correct for the blue color of fluorescent light?

So D50 is the standard for creating paper profiles?

Is there a way to profile for black and white printing with the 9600?

Also, the yellow cast does carry over to the print, not just the soft-proofing. I made a new profile yesterday from the same measurement data and the yellow disappeared. I'm not sure if I used a different viewing condition setting?

Why does the profiling software ask you what your viewing color is? Does is shift the color to respond to that? Why would it do that if your eyes will adjust to that color automatically? Thats why I thought it was compensating for metamerism( of metameric failure).