How to convert three real numbers showing red, green and blue to one real number showing how bright the color is?

Question

Mathematics

There are three real numbers, each of which lies in the interval [0; 1] .

The first real number shows how red the pixel is, the second how much the pixel is green, the third how much the pixel is blue, that is, the classic color representation through red, green and blue (used in JPEG ). It is necessary to convert all these real numbers into one real number lying in the interval [0; 1] and showing the brightness of a pixel. An example for some values ​​from this range:

0 - absolutely black
0.1 - almost black
0.25 - dark gray
0.5 - gray
0.75 - light gray
0.9 - almost white
1 - absolutely white



Required for loading images into the neural network. Tell me which way to think.

Answer 1

Google: "brightness formula of RGB color"

Answer 2

Just the arithmetic average of three numbers.