i need this equation matlab code any body help me.

Answer 1

[Jan]

gbar   = sum(g(:)) / (M * N);
sigma2 = sum((g(:) - gbar) .^ 2) / (M * N - 1);

Looks straight forward. But what about:

sigma2 = var(g(:))

[Image Analyst]

and

gBar = mean(g(:)) % Compute mean over all values in the 2-D matrix.