mathematical operation on each element of gpuArray

How can i do mathematical operation on each element of gpuArray with the equation below? s = 2r(i, j) − r(i, j +1) + r(i, j −1). here r is the image matrix. I've written the code below:

 im = imread('(HTC-1-M7)1.jpg');
tic
 img = gpuArray(im);
    for j =2: size(im,2) -1
        A(:,:,:) = 2*img(:, :,:) -img(:,j+1,:) + img(:, j-1,:);       
    end
B = gather(A);
toc

Is there anyway to apply equation on each element of gpuarray with function like arrayfun without using loop? Thanks in advance.

[Matt J]

Are you certain that it is not a 2nd order differencing filter that you want:

s = 2r(i, j) − r(i, j +1) - r(i, j −1)

[Rouhan Noor]

actually I found it from a research paper from IEEE. They derive this equation for row wise(x-axis) second order differentiation. But i have come to know about imgradientxy function, not sure this function does the same stuff like this equation or not.

Answer 1

[Matt J]

 B=gather( imfilter(gpuArray(img), [+1,2,-1]) );

[Rouhan Noor]

actually I found it on a research paper from IEEE. They derive this equation for row wise(x-axis) second order differentiation. But i have come to know about imgradientxy function, not sure this function does the same stuff like this equation or not.

[Rouhan Noor]

if you don't mind could you explain the code how does it works? I'm newbie in matlab.

[Rouhan Noor]

Is there any builin function in matlab to determine the second order derivative of image like the equation above?

[Matt J]

B=gather( diff(gpuArray(img),2,2) );