how compute the pixel sum for image?

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houssem rouine on 11 Apr 2018
Commented: Walter Roberson on 28 Oct 2019
Hello freinds, I am a beginner in matlab and i want know how compute the pixel sum for image
houssem rouine on 11 Apr 2018
thank you so much for your helping.

Pawel Jastrzebski on 11 Apr 2018
1. Use imread - output to load the image into Matlab and store it as a matrix - it can be anything between 2d and 4D matrix
2. Dimension 1 and 2 of the matrix are width and height of the image in pixels
% load the image into the matrix
dims = size(A)
NoOfPixels = prod(dims)
% Note if 'dims' is bigger than 2 elements then:
% NoOfPixels = prod(dims(1:2))
Walter Roberson on 28 Oct 2019
No, in that code, NoOfPixels is the number of array elements in the image. It is not necessarily the number of pixels: the number of pixels would be dims(1)*dims(2) . The difference comes about for RGB, in which there are 3 array elements per pixel.
If you are looking for the sum of the pixels, you need to define what that means for RGB.
sum(A, [1 2]) %since R2019a