How I solve this equation (delta function)

In the equation for delta as shown in the image attached there is a term being used.... m(j-1) if I take m to be the 1x256 matrix that we got by gamma correction and say that m(j-1) means the j-1 th term of m matrix, then: ==>for j=1, m(0) does not exist, so I have changed that to m(j). If that is the case then, H is a matrix of zeros (256x256). That cannot be right because that means that the output pixels are all 0, irrespective of input pixel values. So Please can help me

Answer 1

[Thorsten]

In this formula m is not a 1x256 matrix, but a function that you can define as, e.g.,

gamma = 2.3; N = 256;
m = @(j) N*(j/N)^gamma;

So m(0) is NOT the zero'th entry of m, which is not defined, but the call of function m with argument 0.