Principle and realization of common shader (i.) grayscale

Gray image is a special color image with the same three components of R, G and B. So grayscale is the process of calculating the gray value, here only the most commonly used weighted average method.

The color image of the YUV space, the physical meaning of its Y component is the luminance of the pixel, which reflects the brightness level, so it can be based on the variation relationship between RGB and YUV color space to establish the corresponding three color components of brightness Y and R, G and B: y=0.3r+0.59g+0.11b, The grayscale value of the image is expressed with this luminance value.

Fragment Shader
Assume that the output value previously computed is color
float grayvalue= Dot (Color.rgb, VEC3 (0.30.590.11 1.0);

Principle and realization of common shader (i.) grayscale