Post Processing with the GIMP

Summary notes and links for my talk last night. I’ll expand a little on this as I find time over the next day or so.

Get the GIMP from It’s a free download. The Windows version weighs in at around 16MB, but it also runs on Mac OS X and Linux. (On Mac OS X you’ll have to install the X11 package too)

Essential GIMP tools for photographers:

  1. Curves
  2. Levels
  3. Crop
  4. Resize
  5. Unsharp Mark

Layers are a very important part of the post processing experience. Learn to use them along with layer masks and modes.

A handy way of creating a polarizer effect on a blue sky is by creating a new transparent layer, set the mode to overlay, and then select the gradient tool. Make sure it’s set to FG->transparent and the foreground colour is black. Draw from the top of your image. Hey Presto!

Dodge/Burn functions do exactly what they do in the darkroom. They brighten and darken areas of the image you apply them to. Remember to apply gently, not like I did last night!

2008-02-11 Update – GIMP For Photographers: Levels covers the basics of using the levels tool!

2 thoughts on “Post Processing with the GIMP

  1. To my mind there only a few things missing in the GIMP that Photoshop has:
    1. Adjustment layers, but the effect can be done with normal layers, mostly.
    2. CMYK printing. I would argue for photographers that this is a non-issue. GIMP can output Jpeg file in RGB colour space. The latest version of GIMP has some support for RGB and CMYK colour spaces but I haven’t really had to play with them.
    3. LAB colour.
    4. 16bit workspace. I only ever wish the GIMP supported 16bits internally when working on a graduated blue sky. There simply aren’t enough shades of blue sometimes in an 8bit palette.

    There are efforts under way to make Photoshop plugins work in the GIMP but there are also lots of free GIMP plugins out there too.

    I think for 99% of amateurs or even if you do make money from your images, then GIMP will do the job fine. If you’re only publishing online then you’re doing yourself a disservice not checking it out.

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