http://www.natrox.org/ami/blizzard1260.png (Warning, 16 MB PNG)
I had to debug an old circuitboard, and to do this I had to recreate the component traces. I scanned the board on two sides, then I used ImageMagick -distort Perspective to correctly align the front and back side so that I could follow every drilled hole in the board. After that, I used gnuplot to create a color-correction polynomial for each side so that the same type of component on both sides would get the same color. I applied the function with -fx in the CIELab colorspace. Then I used a plain -resize in a linear colorspace to get the size down to something more managable than the original high resolution scan, finally converting it to a 24-bit PNG.
This was all done in one command without using any temporary storage, as to maintain as much information as possible until the last stage. None of this could have been done in Gimp, the tool I normally use whenever I don't care much about quality and precision. I did however use Gimp to locate correction points for the perspective correction and to locate areas from where to sample colors.
Here's an seizure-inducing animation to show how well the perspective correction managed to align both sides. It's mostly visible in the small holes around the edge of the board. The original boards were slightly distorted because of my scanning method.
EDIT: Forgot to mention that none of this would have been possible without Anthony's great site about usage examples. I don't think anyone can actually use ImageMagick without those.
