* - maybe try to generate a long switch in color_conv_pixel()
* with optimized entries instead of access to interpolation table
* - most of multiplications in srgb_to_luv_pixels can be replaced
* - maybe try to generate a long switch in color_conv_pixel()
* with optimized entries instead of access to interpolation table
* - most of multiplications in srgb_to_luv_pixels can be replaced