Gimp

Misc

• White balancing an image
  Tools > Color Tools > Levlels >
  select the white doppler and pick a white point in the image ...
  I then do Colors > Brightness and Contrast.
  with still photography use color key cards
• resizing scanned image
  Image > Scale Image > 842 in width, click in height > Scale
  A4 has 595 * 842 pixels @ 72dpi - see What is A4 in pixel dimensions?