MATLAB: How to write this equation in matlab?

Question

Hello everyone.In the below equation can anyone suggest me how to write this eqn in matlab..

L_in (x,y)=0.299.I_in^R (x,y)+0.587I_in^G (x,y)+0.114I_in^B (x,y).

where I_in is input image.

Many thanks in advance..

Answer 1

Images are not indexed (x,y), they (like all matrices) are indexed (y, x) which is (row, column).

So, L_in (x,y)=0.299.I_in^R (x,y)+0.587I_in^G (x,y)+0.114I_in^B (x,y) would be

L_in(y, x) = 0.299 * I_in(y, x) ^ R(y, x) + 0.587 * I_in(y, x) ^ G(y, x) + 0.114 * I_in(y, x) ^ B(y, x);

Looks like a very strange equation though. What are R, G, and B and why are you raising the gray level of the image to those powers? And is I_in a gray scale image (which I assumed above), or an RGB image. If it's an RGB image, you might possibly want (the still weird):

L_in(y, x) = 0.299 * I_in(y, x, 1) ^ R(y, x) + 0.587 * I_in(y, x, 2) ^ G(y, x) + 0.114 * I_in(y, x, 3) ^ B(y, x);

or maybe you want (if you're trying to convert an RGB image into a gray scale image one pixel at a time in a loop):

L_in(y, x) = 0.299 * I_in(y, x, 1) + 0.587 * I_in(y, x, 2) + 0.114 * I_in(y, x, 3);

or (NOT in a loop over x and y):

L_in = 0.299 * I_in(:, :, 1) + 0.587 * I_in(:, :, 2) + 0.114 * I_in(:, :, 3);

or even, more simply:

L_in = rgb2gray(I_in);