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Using grayscale photo images for cmyk output

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    • March 7, 2012 at 8:46 am #61761
      FlyingOil
      Member

      Hello All,, newbie post so apologies if rubbish:

      I have created an Indesign document which contains grayscale photos overlaid with bits and pieces of text. The (human) printer tells me that for an intense black (in his offset printworks) in the black parts of the photo I should use 100%K and 40-60%blue. Others tell me that whatever I do I should have converted the photos to CMYK before using them in Indesign because Indesign won't do the conversion.

      I would like to use the photos as unconverted grayscale files, because that is what I have a lot of, and then get Indesign to do the conversion and allow me to specify this 100%K and 40-60% blue.

      My question is: What's the real truth here and what's best to do, given that I don't have the option of only using CMYK images to work with.

      Any help much appreciated.

      Thanks.

    • March 20, 2012 at 12:57 am #61833
      Gert Verrept
      Member

      Well,

      Grayscale images are images with tints of black. This means that you cannot add another color to them directly, because the color in the pics is either white or black. Indesign doesn't convert the pics. In photoshop you could convert them to duo tones (black and cyan) and print them in that way.

      gert

    • March 20, 2012 at 2:33 am #61834
      Theunis De Jong
      Member

      Create an swatch consisting of 100% black and 50% cyan (there is no 'blue' ;) ). Select your image with the white arrow. Apply swatch.

      Not every grayscale image can be colored this way, because there are lots of ways to create one. If you applied your swatch, check with the Output Separations preview if it did anything.

      .. intense black (in his offset printworks) in the black parts of the photo ..

      It's a strange advice to get from a printer. Usually, they are pretty concerned about large full-black patches in pictures, as these may get printed as mud. Adding yet even more ink (on top of the 100% black) makes it even worse.

      The black-with-an-extra-dash-of-color is called “Rich Black”, and under that name you can find lots of advice on-line, such as David's article on this very site.

    • March 20, 2012 at 5:24 am #61835
      David Blatner
      Keymaster

      I agree with Jongware, but I add that it is far, far better (quality) to open the grayscale image in Photoshop, convert to Mode > Duotone, and use the tools there to add the color as a duotone. See the pdf excerpt from my old (but still relevant, in this case) book:

      Excerpted from Real World Adobe Photoshop CS3 by David Blatner and Bruce Fraser

    • March 15, 2013 at 12:34 am #64413
      WilhelminaTIFF
      Member

      Im not familiar with image in CMYK, my work is on image in RGB, we can convertim age from CMYK to RGB or the vice versa.

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