On 28/11/2016 09:11, Mike Horvath wrote:
> On 11/28/2016 3:53 AM, scott wrote:
>>>> Also it would be surprising to me if the
>>>> human visual range came out exactly as a cylinder (after a brief glance
>>>> of the maths involved), are you sure about this?
>>>>
>>>
>>> The human visual range has a very irregular shape.
>>>
>>> https://en.wikipedia.org/wiki/File:Cie_Chart_with_sRGB_gamut_by_spigget.png
>>>
>>>
>>>
>>> There's a lot of blank empty space around it in every color space. (The
>>> one in the picture is called CIExyY I think.
>>>
>>> I would like to learn how to plot this irregular shape in the near
>>> future.
>>
>> You just need the XYZ colour-matching functions in terms of wavelength.
>> Look here (just click the first "Submit" to get a basic table):
>>
>> http://cvrl.ioo.ucl.ac.uk/cmfs.htm
>>
>> This table then gives you the exact XYZ values for each pure wavelength.
>> XYZ is a linear representation of absolute colour, so you can do a lot
>> of math with them (eg adding, averaging, mixing etc).
>>
>> To get the graph you linked to, you just need to calculate x and y for
>> each of those wavelengths.
>>
>> x = X/(X+Y+Z)
>> y = Y/(X+Y+Z)
>>
>> You'll then find that the x,y pairs give the outline of the graph you
>> linked to, which are the pure wavelengths. The internal area is formed
>> by mixing pure wavelengths, so roughly speaking the further you are away
>> from the boundary the more "wideband" the light is.
>>
>
> Well, I don't understand that.

Which bit?

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