You're likely referring to a fascinating aspect of primate biology where certain individuals exhibit colour vision deficiencies, which in some contexts, can actually offer adaptive advantages. While gibbons typically don't display this trait as prominently, this scenario is more associated with New World monkeys, like howler monkeys or tamarins.

In these species, some individuals are dichromatic (having two types of colour receptors), which can indeed help them to detect variations in texture and pattern that those with trichromatic vision (three types) might miss. This dichromatic vision can be beneficial in environments where distinguishing between camouflaged or toxic foods and safe ones based on texture or pattern is crucial.