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PHP - How to convert RGB color to CIE 1931 color specification

I am creating my own PHP based application where i want to change RGB color into xy format of CIE 1931.

How can i convert my RGB color specs to the CIE color space?

Solution

  • First calculate X, Y and Z with the transform matrix and then normalize the result

    X = 0.4124*R + 0.3576*G + 0.1805*B
Y = 0.2126*R + 0.7152*G + 0.0722*B
Z = 0.0193*R + 0.1192*G + 0.9505*B

    Normalize:

    x = X / (X + Y + Z)
y = Y / (X + Y + Z)