For PBM images, specify image type pbm. Color, gray-scale and monochromatic images are supported. For mono PBM images, two additional image properties are supported.
:foreground foregroundThe value, foreground, should be a string specifying the image foreground color, or nil for the default color. This color is used for each pixel in the PBM that is 1. The default is the frame’s foreground color.
:background backgroundThe value, background, should be a string specifying the image background color, or nil for the default color. This color is used for each pixel in the PBM that is 0. The default is the frame’s background color.
The remaining image types that Emacs can support are:
Image type gif. Supports the :index property. See Multi-Frame Images.
Image type jpeg.
Image type png.
Image type tiff. Supports the :index property. See Multi-Frame Images.
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Licensed under the GNU GPL license.
https://www.gnu.org/software/emacs/manual/html_node/elisp/Other-Image-Types.html