How to convert the RGB image to the gray scale image?

Question

In Matlab, how do I convert an image which is in the red green and blue (RGB) format to a gray scale image without using the toolbox.

Take an average of the channels? `mean(I,3)` – Dan Dec 13 '13 at 09:55 — Dan, Dec 13 '13 at 09:55

score 7 · Answer 1 · edited May 23 '17 at 11:57

7

With "the" toolbox: rgb2gray.

Without "the" toolbox: look here, or here or here or this paper or here or here or ...

That's just the first couple of Google hits for "convert RGB to grayscale" and "convert RGB to grayscale MATLAB".

Summary:

gray = 0.2989*img(:,:,1) + 0.5870*img(:,:,2) + 0.1140*img(:,:,3);

where img is your RGB image.

edited May 23 '17 at 11:57

Community

answered Dec 13 '13 at 09:55

Rody Oldenhuis

@RobertP.: ...trying to make a point subtly :) – Rody Oldenhuis Dec 13 '13 at 09:58
+1 for the luma calculation – Dan Dec 13 '13 at 10:00

1 Answers1