How do I use the FIR filter on an image?

I've hit a roadblock in my code and am unsure of how to proceed, whether I'm missing an entire step involving the filter function or not. This is the code I have currently... Any help is very much appreciated.

clc, clear

Pic = imread('barbara.png');

Pic = double(Pic);

[x,y] = size(Pic);

n1 = 0:x;

n2 = 0:y;

n3 = n2.';

n = n3*n1;

x = 1;

h = x*(n)-x*(n-1)

K = filter([1,-1],1,h);

Y=conv2(K,K,Pic,'same');

figure(1) Disp = uint8(Y);

imshow(Disp)

Answer 1

[Image Analyst]

Make up your 2-D kernel, then pass it in to imfilter().

[Just another student]

Sorry I'm not sure what you mean by this, could you please elaborate?

[Image Analyst]

imfilter is a function that will multiply and sum a small matrix as it slides over the image. For example if you wanted to get an image where each pixel is the result of subtracting the prior pixel's value from the current pixel's value, you could do this:

kernel = [1, -1];
outputImage = imfilter(grayImage, kernel);

Or you could flip the kernel and use convolution:

kernel = [-1, 1];
outputImage = conv2(grayImage, kernel, 'same');