2 Replies Latest reply: Oct 15, 2010 1:07 PM by bpylant RSS

    Background Color Not Filled Correctly to Individual Channels.

    bpylant Community Member

      Before I file a bug report, can someone test this to make sure I'm not missing anything silly or doing something wrong... I don't recall this being an issue with CS4 and before.

       

      Bug:
      When applying a fill to individual channels, Photoshop is not using the background color specified in the Tools palette.

       

      Steps:
      1. Create a new CMYK document
      2. Set your background and foreground colors to c0 m0 y0 k0
      3. Select the C, M and/or Y channel individually and CMD-Delete (or use Edit > Fill) to fill this single channel with the background color.

       

      Result:
      Instead of 0% fill, you get 1%.

       

      Repeat the above steps, but use OPT-Del to fill a single channel with the foreground color (or use Edit > Fill). The fill is 0% as specified.

       

      Repeat the above steps but leave all channels selected. The fill is c0 m0 y0 k0 as specified.

        • 1. Re: Background Color Not Filled Correctly to Individual Channels.
          Rick McCleary Community Member

          Not seeing that behavior here.

           

          I ran your steps 3 ways:

          FG/BG colors: 0/0/0/0

          FG/BG colors: 50/50/50/50

          FG/BGcolors: 100/100/100/100

          Filling individual channels with FG or BG color yielded expected readings in the info panel.

           

          Could it be that the FG/BG colors you ran your test with were not identical? Perhaps hit "D" for default colors to be sure you're at 0/0/0/0.

          Can't think of other reasons why this would be happening.

          • 2. Re: Background Color Not Filled Correctly to Individual Channels.
            bpylant Community Member

            So, I figured out the circumstances that are causing the problem, although I still don't understand why Photoshop is doing this. Turns out that it's becasue we use a custom greyscale color profile; if I switch to Dot Gain 20% the issue goes away.

             

            So, now my questions are:

             

            1. What does the greyscale profile have to do with CMYK channels?

             

            2. Why would Photoshop need to refer to a profile at all in this case? I'm not asking for any sort of conversion, I'm instructing it to fill a channel with a specific value.

             

            2. Assuming that for whatever reason Photoshop needs to use the greyscale profile when working in individual channels (since they are, in essence, four greyscale images that comprise the full-color image), why would it only apply erroneous numbers when using the background color? Filling with a foreground of c0 m0 y0 k0 gives the correct 0% fill.

             

            Hmmmm...