Exploring high-pass filters
The concept of high-pass filters is exactly the opposite of low-pass filters. High-pass filters allow high-frequency components of information (such as signals and images) to pass through them. That is why they are known as high-pass filters. In an image, edges are high-frequency components. The kernels we use in high-pass filters boost the intense components in an image. That is why when we apply high-pass filters to images, we get the edges in the output.
Note:
You can read more about high-pass filters at https://diffractionlimited.com/help/maximdl/High-Pass_Filtering.htm. Another type of signal filter is band-pass filters, which allow signals in a range (or band) of frequencies to pass through them. These filters allow us to highlight the edges in images and reduce the noise by using blurring at the same time. You can read more about them at https://homepages.inf.ed.ac.uk/rbf/HIPR2/freqfilt.htm.
