About Luminance Format

[Poma]

I'd like to ask a question about luminance color format in OpenGL

If the input color data (or texture row data) is in the type GL_LUMINANCE, there is a byte to present a luminance data for each texel. How do i get the RGB value from luminance byte? Or what do i need to do on color buffer when the input data is in luminance form?

What i think is just multiple the color value with the luminance value, is that correct?

but why Luminance value is 0.3*R+0.59*G+0.11*B
is there any reason?

thanks

[waramp]

The constants 0.3, 0.59 and 0.11 are there to represent the sensitivity of the human eye to Red Green and Blue light.

Its just a weighted average of the RGB color that mimicks how we see colors.