1 Reply Latest reply on Apr 28, 2008 4:44 AM by Lou Dina

    adjusting images for yellow stock

      We have to adjust images to print on a yellowish stock that has a LAB reading of 94,-1,8 (CMYK=4,3,9,0). Should I just build a curve that pulls the cmyk down by those amounts? Or should I have our press actually run an IT8 chart on that stock, read it with a spectrolino and build a new ICC with GretagMcbeth?

      The colors are really swatches in Illustrator, so each global color swatch would need to be tweeked. It would be much simple just to convert the documents color space from say US Sheetfed Uncoated to "Special Yellow stock.icc".

      Any thoughts?
        • 1. Re: adjusting images for yellow stock
          Lou Dina Level 3

          There are probably many different answers to this question depending on what you want the outcome to be. Normally, people select a warm, yellowish stock because they WANT the warmth of the stock to show, otherwise they would select a more neutral stock. This is true of jobs printed on an inkjet or press. I like a slightly warm paper for many of my prints, so I select a warm paper. Others look better on a cool white paper.

          The color of the paper stock will always affect the quarter tones and highlights much more than the midtones and shadows, since much less ink hits the paper to cover up the substrate color. If you actually want your highlights to be more neutral, you will end up using some cool inks, such as cyan, to help neutralized the yellow of your paper. This will decrease the dynamic range of your print, since you are laying down ink in highlight areas. It doesn't always look natural, in my opinion (this is akin to using Absolute colorimetric rendering, which is fine for simulations, but I don't use it for printing a real job).

          Gretag's ProfileMaker allows you to build profiles with a "neutral" or "paper gray" gray axis. It ONLY affects Perceptual rendering, not Relative Colorimetric. In paper gray rendering, the color of your paper base will affect the neutrality of the image all the way from highlights to shadows. It is like using the exact same press plates on two different paper runs, one on neutral white paper, and the other on warm, yellowish paper. The paper color will affect the entire tonal scale.

          The "neutral" axis profiles will print highlights and quarter tones like the paper gray profile, allowing the color of the paper base to show through and skew the gray axis, but it adjusts the midtones and shadows so they are more neutral (more like absolute colorimetric in the mids and shadows).

          I guess you could also attempt to edit the profile with a profile editor, but that might be a difficult proposition. I'm not sure you would like the results.

          I'm not 100% sure what you wish to accomplish. Hope this helps some.