img2png.py – convert several image formats to PNG format.
img2png.py [options] image_files...
-o <dir> The directory to place the .png file(s), defaults to the current directory. -m <#rrggbb> If the original image has a mask or transparency defined it will be used by default. You can use this option to override the default or provide a new mask by specifying a colour in the image to mark as transparent. -n <name> A filename to write the .png data to. Defaults to the basename of the image file + ‘.png’ This option overrides the -o option.