How to take sum of grey value of an image

I want to calculate sum of grey value of an image. I have enclosed a image . So kindly provide MATLAB code

Answer 1

[Rik]

IM=imread('image.png');
%IM=mean(IM,3);%convert RGB to grey
IM=rgb2gray(IM);
sumval=sum(IM(:));

You forgot to attach the image. You should really consider a crash course Matlab, any half-decent tutorial will learn you how to do this.

[Guillaume]

Note that while taking the unweighted mean of the red, green and blue channels is certainly a possible way of converting to grey, it is not the most conventional. Most grey conversions put more weight on the green channel ( rgb2gray uses the weights 0.299, 0.587 and 0.114 respectively).