[PATCH 2/2] Move the EDID parsing to its own file

[Bill Spitzak]

Graeme Gill wrote:
> Bill Spitzak wrote:
>> The Y of the primaries can be used as alternative method of specifying the whitepoint. (convert the
>> 3 Yxy colors to XYZ, add them, then convert back to Yxy and the xy is the whitepoint, I think).
> 
> Correct, but this assumes the display is perfectly additive. Real world ones mightn't be, so
> Yxy or XYZ x RGBW does provide extra information.

I suppose that is possible if the primaries and whitepoint were all Yxy 
triples, because that provides 12 degrees of freedom. However I have 
always seen them specified as xy pairs thus giving 8 degrees of freedom, 
which is less than the 9 degrees of freedom from three Yxy triples.

Also non-additiveness is usually considered a second step after 
conversion to additive primaries. I have doubts it can be specified by 
just one extra point in the color space.

>> I think the reason rgb sets are specfied as 4 pairs of xy (the three primaries and the whitepoint)
>> instead of 3 triples is to remove the arbitrary multiplier that makes there be 9 numbers instead of 8.
> 
> A lot of display folk are very chromaticity diagram oriented - they are used to just
> specifying xy, and it's nice to have the white point be explicit so you can more easily
> check what the white point color temperature is.

xy of the whitepoint does define the color temperature. Possibly you are 
thinking of X and Z?