Getting wrong value of sum

I am writing a code in matlab and dealing with images. I am basically finding the sum of value of each pixel, for this I am using code "sum=0; for i=1:584 for j=1:40 img(i,j) sum=sum+img(i,j) end end" here img(i,j) is any gray-scale image. the problem arises here is that the value of "sum" never accedes from 255. Hence I can't get correct value of sum. Someone please help me in finding correct values of sum

Answer 1

[Oleg Komarov]

First of all don't use sum as a variable since it's a MATLAB function, next time you try to call the function it will be obfuscated by your variable.

Second img is a uint8 class which cannot store more than 256 values (zero included):

intmax('uint8')

Do the following

out = sum(double(img(:)))

Note that I am using the function sum to perform the summation and assignin the value to something else but any MATLAB function named variable.

[Khawaja Asim]

Thank you dear!!! You have helped me alot.. :) I am working on it furthur, do help me whenever next time I have any problem