Blend together two portable pixmaps
ppmmix fadefactor ppmfile1 ppmfile2
Reads two portable pixmaps as input. Mixes them together using the specified fade factor. The fade factor may be in the range from 0.0 (only ppmfile1's image data) to 1.0 (only ppmfile2's image data). Anything in between gains a smooth blend between the two images.
The two pixmaps must have the same size.
pnmcomp is a more general alternative. It allows you to mix images of different size and to have the fade factor vary throughout the image (through the use of an alpha mask).
pnmcomp(5), ppm(5)
Copyright (C) 1993 by Frank Neumann