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How to reduce number of colors in an image

Feb 5, 2012 10:05 PM

Tags: #reduce_colors

I am fairly new to Photoshop and I'm learning as I go, so I apologize for using your time.  I haven't worked with images that much - I've used MS Digital Image Suite with photos from my camera.  That's the extent of my knowledge.


I am taking over a job from someone who is gone and I can't ask him how to do this.  He used Photoshop to reduce the number of colors in an image (for example, a color drawing or clipart) to 2-6 colors.  I haven't been able to figure this out.  I've visited this site that explains how to reduce tones but it's still a lot of colors.  I thought I might learn something from this link that explained how to make Photoshop cartoons, but I didn't.  I've done a lot of searching but nothing seems to explain this.  I know that the other guy had some knowledge of Photoshop but he wasn't a power user.


Thanks to anyone who will help me.  (I am using CS5.)

  • Currently Being Moderated
    Feb 5, 2012 10:16 PM   in reply to erleichda

    Naturally there are several options for what you are asking – but it also depends on what you really need as end result.

    One possibility might be

    Layer > New Adjustment Layer > Posterize

    Another one would be to create copy of the image and use

    Image > Mode > Indexed Color

    and then edit the Palette (number of colors for example) and Options as needed.

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  • Trevor Dennis
    5,938 posts
    May 24, 2010
    Currently Being Moderated
    Feb 5, 2012 10:21 PM   in reply to erleichda

    It sounds like you are talking about a cartoon type gif image, and the Indexed colour is definitely the way to do that as above, but if you want to keep it as a jpg then Save for Web is a very useful tool, and you can see what affect it has on file size as you adjust the output options.  But I think you already had the right answer.

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  • Currently Being Moderated
    Feb 8, 2012 8:00 PM   in reply to erleichda

    It is not clear to me what your issues are with the previous suggestions.


    If you change your image to index color mode, specify 4 colors, force custom colors and select your choice of 4 Pantone colors then it would seem that ALL your criteria are met.  Perhaps you could post an example of an original & modified imaged that the previous designer produced and specify what is wrong with the index color approach, someone might be able to help.



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  • Pierre Courtejoie
    7,043 posts
    Jan 11, 2006
    Currently Being Moderated
    Feb 9, 2012 12:26 AM   in reply to erleichda

    Are you sure that he was using Photoshop? (see my third solution)

    There are some plug-ins for Photoshop, but they basically do the same as the posterize or index mode: (commercial) see this panel for colorizing comic art:


    I would rather use posterize, as an adjustment layer, as you can control it.

    Try with this layer stack, from bottom to top:

    Convert the original image in a Smart Object, in order to use Smart filters and blur the image (Gaussian Blur, or noise>median or blur>smart blur or blur>surface blur could be interesting internatives) would be useful, to make smoother posterized areas.

    A dodge/burn layers (a neutral gray layer in overlay mode) to adjust areas using the Dodge/burn tools.

    the Posterize Adjustment layer, with very few colors

    On top of it, put a gradient map adjustment layer, to control the posterized colors

    Vectorizing in Illustrator can also be used to reduce the number of colors. Live Trace: 7d0100196cbc5f-6229a.html

    More on the topic: 7d0100196cbc5f-622aa.html

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