The colors , and are supposed not to be gamma corrected. If they are colors obtained from gamma-corrected image files (JPEG, PNG, etc.), they need to be linearized before working with them, which is carried out by scaling the channel values to the range and raising them to the gamma value of the image, which for images in the sRGB color space can be assumed to be about 2.2 (even though for this specific color space, a simple power relation is just an approximation of the actual transformation). Modern graphics APIs have the ability to perform this gamma correction automatically when sampling from a texture or writing to a framebuffer.