# What happens when you wrap a 3x3 kernel at the corners of an image?

I am puzzled by what actually happens when you process border cases when applying an image filter. For instance if I apply a 3x3 Gaussian kernel to the top left pixel[0][0], the remaining pixels that are unable to convolute will go to the right and bottom of the image. But do you multiply them again or u replace the original pixels?

[1, 2, 1,
2, 4, 2,
1, 2, 1] // 4,2 & 2, 1 will convolute with the pixels in image but how about row 1,2,1 and col 1,2,1 ?