How to check whether an NSImage is GrayScale or RGB?

Is there any way to check an NSImage's color type in OBJC? I wanna know whether the image is GrayScale or RGB. Any suggestions would help, thanks~

Solution

If you can get the image's color space (possibly from its underlying CGImage) you could determine the number of components in it. If its < 3 you have a monochrome image.

However an image could still be monochrome and have a color color space.