J = VL_IMINTEGRAL(I) calculates the integral image J of the image I. I must a matrix with DOUBLE, SINGLE, UINT32, or INT32 storage class. J is given by
J(i,j) = sum(I(1:i,1:j)).
J has the same size as I and the same storage class.
The following identity holds:
VL_IMINTEGRAL(ONES(3)) = [ 1 2 3 ; 2 4 6 ; 3 6 9 ]
See also: VL_HELP().