It occurred to me that while the human colour vision is trichromatic, i.e., every colour can be represented as a three-dimensional point (Red,Green, Blue), the Klingon colour vision might well be bichromatic with just two dimensions, {Doq} and {SuD}. In this case, all colours Klingons distinguish can be represented as the following picture: https://cdn.discordapp.com/attachments/235416538927202304/617793348433870868... Here I mapped the (Doq,SuD) Klingon colour to the (Doq,SuD,SuD) RGB colour to avoid the difficulty of getting white from combining red and green in RGB, but Klingons would see a (100%,100%) colour as white. So on the picture we see {qIj}, {chIS}, {Doq}, and {SuD} at the corners, the colours close to black are {Hurgh}, the ones close to white are {wov}, the ones away from the grey diagonal are {chum}, and the ones close to that diagonal are {tlhoD}. Also, we learnt a few days ago that {qalmuS} is used to distinguish colour from black-and-white. Otherwise, if Klingons are bichromatic, then they would see any non-greyscale colour as either a variety of {Doq} or a variety of {SuD}, so it is not much possible to use colour as a defining attribute of an object. No wonder they are irritated by other species making distinctions where they see none! I wonder if there is a Klingon word meaning "be grey".