If an input infile is specified, then the output file names will be in the form "rlefileroot.{alpha, red, green, blue}", where rlefileroot is infile with any ".rle" suffix stripped off. If the option -o prefix is specified, then the output file names will be of the form "prefix.{alpha, red, green, blue}". If neither option is given, then the output file names will be "out.{alpha, red, green, blue}". Input will be read from infile if specified, from standard input, otherwise. If more channels than just red, green, blue, and alpha are present in the input, numeric suffixes will be used for the others.