How the eye perceives colour can cause quite a few problems with data visualization. Say you have a range of 1,000 values ( eg height of a surface) and decide to use colour to represent height with the 1,000 increments split evenly across the regular spectrum of colours, weird things happen.
What you will find is people see big 'changes ’ in the data where the data maps across the Blue / indigo / violet range and in the Yellow orange red transition, but data will look very ‘flat’ in the green band. Say you set height zero to be violet and ,10000 to be red, with all the mapping evenly spaced. A change from 200 to 400 would sweep you through moving from indigo to blue and appear to have a lot of change in height. The next change in height form 400 to 600 would all look green with almost no apparent transitions. You then get a sharp contrast form green to yellow, possible with minimal change in the underlaying data.
Explained much better here
Intro to his full series here
And for those who like representing data with colour some excellent reasons not to use the normal rainbow spectral range, and if you are a MatLab kind of person, some great colour maps here.
Right, just as long as it is certain that the L cone itself is not sensitive to blue.
Sorry, I don’t see what that link means or that there is anything special with yellow. Yes you can make yellow (at least but many more than) two ways, but the same is true of cyan, orange, chartreuse, or puce. Two colors can be perceived the same but completely spectrally different. Yellow is not special.
‘Every seven-year-old kid in America is taught that “the opposite of red is green” and “the opposite of blue is yellow.”’ I remember 7+/-2 year old tlh making drawings where red was opposed to green; blue and orange; yellow and purple. When you have a three-primary system, there is no opposite color unless you go into the secondary colors that are a combination of 2/3 of the primaries (r+y=o; r+b=p; y+b=g). So those seven year olds are essentially wrong. Dumb kids :D. RBY vs. CMY is a rather arbitrary distinction.
The part about the “filters,” i.e. the ganglion cell layer of the retina and LGN leading to the opponent colors - if you look at color spaces, it is not unintuitive to see how R+G = yellow signal, in the absence of blue. BTW, Filter #3 is essentially not correct: due to a biological quirk the S/blue cones don’t contribute much to our intensity perception. L/M cones are essentially identical except for their sensitivities, whereas S cones are sparser on the retina, in different areas, coarser resolution, and encoded on a separate chromosome. So the differences are much larger and they do not work well without the others. The last section on color constancy occurs further on; in the cortex. Essentially our perception is a result of complex calculations in our brain, that get input from simpler cortical calculations, that get input from lower brain areas, that get input from our retina. So we can look at what the cones are doing, but it doesn’t translate directly, without tons of intermediate steps, to our perception.
No, but depending on how you define it, there is either exactly one way to make yellow, or there are many, many ways. As part of the EM spectrum, it has no meaning except as how we perceive it as a color. When we reach color opponency, the spectral information is essentially lost and we only have relative activation. But comparing them is apples and oranges.
I´m aware of that; my question concerned the names we give to the colours. I was wondering whether there are non-adjacent parts of the rainbow spectrum that are commonly referred to by the same name.
That is an interesting question. I don’t believe that there are any in the English language. Regarding other languages, according to the research of Paul Kay and Luisa Maffi, there are languages that have a single word to describe red and yellow, or blue/green, or yellow/green, or yellow/green/blue, but in each of these cases the colors are adjacent in the spectrum. Some languages, they say, have a single word for Black/Green/Blue, White/Red/Yellow, or Black/Blue, but since black and white aren’t spectral colors then they’re irrelevant to the question.
Regarding the WCS, and maybe not a direct answer to the OP (as it is Munsell not spectrum, although terms are adjacent from what I can tell and I hope it helps): they ask two basic questions. 1) Given an array of color chips, what is the “best” blue (green/red/etc.), and 2) For each of these chips, what color is it. This gives us a rough analogy of central tendency and variability. For example, English.
