https://stackoverflow.com/questions/17949796/how-many-unique-values-are-ther... ppl here come up with this number: 1,065,353,215. so ... even between 0.0f and 1.0f there is quite a number of ... numbers. Still, out of range numbers useful in photo work like here https://ninedegreesbelow.com/photography/gimp-tone-map-with-levels.html found via bugzilla bug filled for gimp: https://bugzilla.gnome.org/show_bug.cgi?id=737925 "*Bug 737925* <https://bugzilla.gnome.org/show_bug.cgi?id=737925> - Some filters / operations provide float values superior to 1.0" on CinGG plugins I found only exactly one instance of clamp line as Andrea suggested: grep "CLAMP(output, 0, 1.0)" -r plugins plugins/histogram/histogram.C: CLAMP(output, 0, 1.0); plugins/histogram/histogram.C: CLAMP(output, 0, 1.0); and nothing more.