to_pseudogray
Arguments:
- _max_step>=0,_is_perceptual_constraint={ 0 | 1 },_bits_depth>0
Description:
Convert selected scalar images ([0-255]-valued) to pseudo-gray color images.
Default values:
max_step=5, is_perceptual_constraint=1 and bits_depth=8.
The original pseudo-gray technique has been introduced by Rich Franzen [
http://r0k.us/graphics/pseudoGrey.html].
Extension of this technique to arbitrary increments for more tones, has been done by David Tschumperlé.