xpmtoppm

Convert an X11 pixmap to a PPM image. More information: https://netpbm.sourceforge.net/doc/xpmtoppm.html.

xpmtoppm path/to/input_file.xpm > path/to/output_file.ppm

xpmtoppm --alphaout path/to/alpha_file.pbm path/to/input_file.xpm > path/to/output_file.ppm