How to obtain sum of RGB color values of a pixel?

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Anushka
Anushka on 27 May 2015
Commented: John D'Errico on 27 May 2015
How to obtain sum of RGB color values of a pixel?
Without using I(:,:,1) ,I(:,:,2),I(:,:,3).
  1 Comment
Stephen23
Stephen23 on 27 May 2015
Edited: Stephen23 on 27 May 2015
It is important to note that the sum of the R, G, and B values is not the same as the grayscale! This is because each of the R, G, and B values contribute unequally to the luminance, so they cannot be simply summed to get the grayscale equivalent of a color pixel. If you want the grayscale value, then the easiest way is to use rgb2gray.

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Accepted Answer

Titus Edelhofer
Titus Edelhofer on 27 May 2015
Hi,
something like
sum(I, 3)
?
Titus
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Titus Edelhofer
Titus Edelhofer on 27 May 2015
Hi,
what do you mean b "not properly". Was there an error? Result not as expected (see comment by Stephen on grayscale)?
Titus
John D'Errico
John D'Errico on 27 May 2015
Probably the image is uint8, so summing the pixels will overflow. Better might be
sum(double(I),3)

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