The clipping and black bands are caused by the grayscale conversion.
Some components will get values higher than one.
color = rgb<0.1,0,1>
gray = 0.3 * red + 0.59 * green + 0.11 * blue (NTSC formula)
gray = 0.14
expgray = 1 - exp(-10*gray) = 0.75
expgray/gray * color.blue = 5.4
_____________
Kari Kivisalo
