Simpler way to implement Kernel density

Hello, Iv'e been trying to implement this equation into matlab:

omega is some known region of the image u1.

and p1,i is:

pay attention u1 is an image (column ordered), an p1,i supposed to be calculated in each pixel of this image.

now, iv'e calculated p1,i in this way:

 [f1,xi1] = ksdensity(u1(:),1:255);
 p1_u1 = reshape(f1(floor(u1(:))+1),M,N);

now my problem is to calculate the former equation.

iv'e tried with "for" loop but its taking forever..

any other suggestions? maybe there's a way using "ksdensity" and change the value inside the integral?

Thanks!