Sharpening

Applying the sharpening filter will sharpen the edges in the image. This filter is very useful when we want to enhance the edges of an image that's not crisp enough. Here are some images to give you an idea of what the image sharpening process looks like:

As you can see in the preceding figure, the level of sharpening depends on the type of kernel we use. We have a lot of freedom to customize the kernel here, and each kernel will give you a different kind of sharpening. To just sharpen an image, as we are doing in the top-right image in the preceding picture, we would use a kernel like this:

If we want to do excessive sharpening, as in the bottom-left image, we would use the following kernel:

But the problem with these two kernels is that the output image looks artificially enhanced. If we want our images to look more natural, we would use an edge enhancement filter. The underlying concept remains the same, but we use an approximate Gaussian kernel to build this filter. It will help...