The following graph shows the sensitivity for eye cones and rods, but I want to know e.g. what is the red cone sensitivity for a wavelength of 500 nm?
How can I find an answer for questions like this?
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$\begingroup$ You read it from the graph, right? Find 500 nm on the x-axis, draw a vertical line at that point, find the height of the red curve on that vertical line, and read on the y-axis what the sensitivity is. Don't expect any natural exact analytic formula. But you may find functions that fit the graphs rather well. $\endgroup$– Luboš MotlCommented Jun 29, 2016 at 5:59
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$\begingroup$ That formula is what I'm looking for Luboš Motl $\endgroup$– Ahmed ElsawyCommented Jun 29, 2016 at 11:50
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$\begingroup$ Well, if you were rational, you wouldn't be. Cones and rods are extremely complex objects. $\endgroup$– Luboš MotlCommented Jun 29, 2016 at 12:32
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$\begingroup$ @LubošMotl I mean a function that fits the graphs. $\endgroup$– Ahmed ElsawyCommented Jun 30, 2016 at 5:23
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$\begingroup$ Just use a polynomial times a Gaussian and adjust the coefficients. Or try something else. None of these options will be dramatically more convenient than others. I already told you about thrice that there is no "the formula". $\endgroup$– Luboš MotlCommented Jun 30, 2016 at 5:44
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1 Answer
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See the CIE 1931 color space, it is based on the sensitivity of the cones. You can find standards and tabels on the site of The Colour & Vision Research laboratory and database. The functions can be downloaded in cvs, xml, tabular or plot format, with stepsize of 0.1 nm, 1 nm or 5 nm. No mathematical formula, but a lookup or a formula doesn't make much difference when used in a program (unless you hoped for a useful formula like a normal distribution. No such luck I'm afraid)..
This pdf has some more info.
