Gimp

To process a portrait

1. white balance
2. remove background
3. remove red-eye
4. (optional) white balance
5. add new background
6. blend edges with fuzzy circle paintbrush and/or blur tool
7. (optional) white balance again

To remove background

If you have an early version of gimp, use Quickmask to select the foreground image. For version 2.3 and up, use the Foreground Extractor.

Select foreground with Quickmask

• http://software.newsforge.com/article.pl?sid=05/04/27/1327225&tid=75&tid=131
• Select -> Toggle Quickmask
• Choose eraser tool and erase the foreground image
• If you go outside the lines of your object, click Select -> Invert, then click Select -> Toggle Quickmask, and use the eraser again to "put back" the mask.
• When you are done, toggle the quickmask off. You should see a marching outline around your foreground image.

Select foreground with Foreground Extractor (Gimp 2.3+)

• Select the foreground extraction tool and follow the prompts in the status bar
• After you hit Enter, you should see a marching outline around your foreground image.

Create image without background

• Once the extracted image is highlighted, do Edit -> Copy
• In the Layers window, create a new transparent layer and select it
• Do Edit -> Paste
• In the Layers window, you should see the pasted image as a floating layer
• Right-click the floating layer and choose "anchor layer"
• Select the old non-transparent layer and delete it.

Soften the edges of your cutout

http://www.gimptalk.com/forum/topic/Softening-The-Edges-Of-Your-Cutouts-1603-1.html

Make Background Transparent

http://aplawrence.com/Linux/crousegif.html

Resize an Image

Choose Image -> Scale Image.

Remove Red-Eye

http://gimp.org/tutorials/Red_Eye_Removal/

http://gimpguru.org/Tutorials/RedEye2/

I've had luck with the Fuzzy Selector and the Brightness/Contrast tool.

Best yet: Filters -> Enhance -> Red Eye Removal

Auto Color Levels

Colors -> Auto -> White Balance