Thrown from all the functions...
Color format which you can pass to the read and write functions.
Reads an image from file. req_chans defines the format of returned image (you can use ColFmt here).
Reads an image from a buffer. req_chans defines the format of returned image (you can use ColFmt here).
Returns width, height and color format information via w, h and chans. If number of channels is unknown chans is set to zero, otherwise chans values map to those of ColFmt.
Writes an image to file. req_chans defines the format the image is saved in (you can use ColFmt here).