Do it with the GIMPBasic Areal EffectsSharpeningAnswer to how one can sharpen

4.2.1. Answer to how one can sharpen

Demo

  1. Open lena.png
  2. Invoke the "Convolution Matrix" dialog.
  3. Type 12 in the middle square and -1 in the 8 surrounding squares.
  4. Type 4 as a divisor (12 + 8 * (-1) == 4).
  5. Apply.

Written by Shlomi Fish