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| Function: | im.matrix.saturation | (level, desat=(0.2126, 0.7152, 0.0722)): |
Constructs an im.matrix that alters the saturation of an image. The alpha channel is untouched.
level - The amount of saturation in the resulting image. 1.0 is the unaltered image, while 0.0 is grayscale.
desat - This is a 3-element tuple that controls how much of the red, green, and blue channels will be placed into all three channels of a fully desaturated image. The default is based on the constants used for the luminance channel of an NTSC television signal. Since the human eye is mostly sensitive to green, more of the green channel is kept then the other two channels.