raster
When raster-color is active, specifies the combination of source RGB channels used to compute the raster value. Computed using the equation mix.r * src.r + mix.g * src.g + mix.b * src.b + mix.a. The first three components specify the mix of source red, green, and blue channels, respectively. The fourth component serves as a constant offset and is not multipled by source alpha. Source alpha is instead carried through and applied as opacity to the colorized result. Default value corresponds to RGB luminosity.
This is an Expression representation of "raster-color-mix".