pix-threshold-to-binary

in - PPIX - 4 or 8bpp
in - THRESH - if src pixel is < THRESH, dest is 1, else dest is 0. (Max pixel value for 8bpp == 255, 4bpp == 15.)
returns: dithered 1bpp ppix or #f on error.

chickadee » leptonic » pix-threshold-to-binary