rgb_premult - chung-leong/qb GitHub Wiki
rgb_premult - Perform pre-multiplication on RGBA values
float[4] rgb_premult( float[4] $pixel )
rgb_premult() multiplies the red, blue, and green values of a pixel by its alpha value.
rgb_demult() performs the reverse operation.
Parameters:
pixel - The RGBA values to convert. It can be a single four-element array or an array of such arrays.
Return Value:
An array containing the pre-multiplied RGBA values. The return value will have the same length as pixel.
Version
1.4 and above.