MATLAB: Mean luminance Values of an Image

Question

Hi ALL,

I want to calculate the means luminance value of an image block

i found the formula is..

 luminance= 0.3 R + 0.59 G + 0.11 B

but how i can calculate the R, G and B values.

i know that

R=rgb_img(:,:,1) 
G=rgb_img(:,:,2) 
B=rgb_img(:,:,3)

but it give in the shape of matrix, i think i need only a single value of R,G and B, to use above luminance formula.

please help me out.

Thanks in Advance

Answer 1

mean2(rgb2gray(rgb_img))

provided you have the toolbox installed.

Otherwise, calculate a luminance array using the R, G, B arrays, and then mean2() the luminance array.