# pnmindex > Build a visual index of multiple PNM images. > See also: `pamundice`. > More information: . - 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}}`