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Saving Extra Channels

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  • Saving Extra Channels


    I have a picture that has quite a lot of yellow in it, so I duplicated the Blue channel and lowered it's opacity. The image looks much better. But when I try to save it, the blue goes away. Is there a way to save an extra channel into the picture? Also is there a way to put a mask on a channel, like you would on a layer, so that only certain parts get the blue? I'm wondering if I should be using something other than channels to do this. Maybe a new layer that's all blue as a low opacity overlay or something? Is there a different/better way to take out some of the yellow? I really like the way it looks with the channel. Any help appreciated.

    So I messed around with hue, saturation, color balance, channel mixer, etc, and I finally got something close to what I had achieved with simply adding an extra blue channel. Then I went to put a layer mask on it to cover one spot, and suddenly the extra blue channel was there! But it still won't save. Clearly I fundamentally misunderstand something about channels, but I've been looking all day and I can't figure out what it is. Most people seem to just use them to select things. I did read that you can't save alpha channels to jpegs, but I don't think the blue copy is an alpha channel, is it? Thanks so much.
    Last edited by Ana M; 05-29-2012, 09:52 PM. Reason: Update

  • #2
    Re: Saving Extra Channels

    Any channel besides the color channels is an alpha channel. That includes your duplicate blue channel. Alpha channels don't contribute to color information (unless they're spot colors, but believe me, you DON'T want to go there) so it's a little difficult to tell what you are doing but in general, it hasn't been necessary to directly edit a color channel since around 1993 or '94, since the advent of adjustment layers. Selective color, channel mixer or curves would accomplish all that you describe without actually altering the pixels until you flatten the file.

    As for preserving channel and layer information, save a .psd file as your editable master, then save whatever version you need along with it. JPEGs won't save layers or channels.


    • #3
      Re: Saving Extra Channels

      Another option would be to the following: Duplicate the background layer, select the Blue channel of the duplicate layer and then Image>Apply Image selecting the blue channel and the blend mode and opacity that gives you the effect you want. After you complete and click OK, just add a layer mask to that layer and mask out whatever you want affected.
      You will need to save the file as a .psd or a .tiff to retain both layers and the layer mask.
      Regards, Murray


      • #4
        Re: Saving Extra Channels

        Thanks! Yeah, I was using spot color, but since it isn't saveable as a jpeg I'll give it up I'll keep reading about color correction. What do you mean by jpegs won't save layers?


        • #5
          Re: Saving Extra Channels

          Originally posted by Ana M View Post
          Thanks! Yeah, I was using spot color, but since it isn't saveable as a jpeg I'll give it up I'll keep reading about color correction. What do you mean by jpegs won't save layers?
          The jpg file format only supports a single layer of RGB (3 channels), no alpha channels, and no additional layers. If you have more than one layer in a jpg file, the file will be flattened and then saved. JPG files only support 8 bit images.
          Regards, Murray


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