pnmindex
Build a visual index of multiple PNM images.
TLDR
Produce an image containing thumbnails of the specified images in a grid
$ pnmindex [path/to/input1.pnm path/to/input2.pnm ...] > [path/to/output.pnm]
Specify the size of the (quadratic) thumbnails
$ pnmindex -size [50] [path/to/input1.pnm path/to/input2.pnm ...] > [path/to/output.pnm]
Specify the number of thumbnails per row
$ pnmindex -across [10] [path/to/input1.pnm path/to/input2.pnm ...] > [path/to/output.pnm]
Specify the maximum number of colors in the output
$ pnmindex -colors [512] [path/to/input1.pnm path/to/input2.pnm ...] > [path/to/output.pnm]
