Readonly_Fraction of the value channel range that is set to 0. The value should be in the range from 0 to 1.
Default is 0.0.
Fraction of the value channel range that is not set to 255. The value should be in the range from 0 to 1.
Default is 1.0.
Maps image value channel so that all the pixels darker than the black point are set to 0, all the pixels brighter than the white point are set to 255, and the pixels in between are linearly scaled.