January 20, 2019

Fixing Your Holiday Photos With GIMP - page 2

Exposure Settings, Healing Blemishes

  • December 22, 2009
  • By Akkana Peck

Most cameras, even camera phones, let you adjust the sensitivity of the sensor: look for a setting called "ISO" or "speed" and set it to a high number, like 400. Many cameras also offer "exposure compensation", where you tell the camera to make the photo darker. Sometimes this is buried deep in the menus, so check your manual if you're not sure.

figure 4
figure 4


Exposure compensation will give you an image that's too dark, and fixing that is easy. Choose from three tools, all in GIMP's Colors menu: Brightness->Contrast, Levels, and Curves. Which one you choose is a matter of taste; Brightness->Contrast is the simplest, but my favorite is Curves (Figure 4). Just drag the curve upward to make the image brighter.

But the high sensitivity also made that dark image grainy (Figure 5), and that's harder to fix.

figure 5
figure 5

If you're targeting small images for the web, try using just enough Filters->Blur->Gaussian Blur... to smooth out the image before you scale down, then Filters->Enhance->Sharpen on the scaled-down image. Or download the external plug-in "GREYCstoration": Fedora and Mandriva have greycstoration packages, while Ubuntu includes it in the gimp-plugin-registry package. Or download the source from cimg.sourceforge.net. It shows up in Filters->Enhance->GREYCstoration.

Touching up

Back to the photo in Figure 1, did you notice the chocolate stains on his cheek? Cleaning up minor blemishes is fairly easy in GIMP.

figure 6
figure 6


The Heal tool (Figure 6) is perfect for small spots. Use it with a large fuzzy brush: if the largest brush still isn't as big as the spot you're trying to fix, use the Scale slider to make the brush bigger. Zoom way in (150%, 200% or more) so you can see more detail.

You're going to be copying small areas from one part of the photo, called the source region, to the part you want to fix, the destination. Use Control-click to select the source, and GIMP will draw a circle around it the size of the brush (Figure 7). Then click on the spots you want to fix. Heal will try to combine the texture of the source with the color and lighting of the destination. Voil´┐Ż! no more chocolate spots.

figure 7
figure 7


The Heal tool works best clicking in a few small spots. If you need to copy a larger part of a photo, use the regular Clone tool, or Copy and Paste. A combination of these tools can fix most of your photo problems. So have fun shooting during the holidays!

Akkana Peck is a freelance programmer whose credits include a tour as a Mozilla developer. She's also the author of Beginning GIMP: From Novice to Professional.



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