How weights are assigned to each RGB component in function rgb2gray

In function rgb2gray, Gray=0.299*R + 0.587*G + 0.114*B, i understand it is a standard formula but can anyone help me understanding on how the weights for each channel are computed?

[Jing]

What do you mean by channel? Do you mean the 'R', 'G' or 'B' component? That's explained in color theory or color model. If you're interested, try to search that.

Answer 1

[Image Analyst]

It comes from the luminous efficacy curve. See http://en.wikipedia.org/wiki/Luminous_efficacy