OpenCV 4 with Python Blueprints - Second Edition

Understanding CNNs

In Chapter 1, Fun with Filters, you learned about filters and convolution. In particular, you learned how filters can be used to create a pencil sketch image. In the pencil sketch, you could see the points in the image that had a sharp change in value, that is, they were darker than those that had a smooth change.

From that point of view, the filters that we applied can be thought of as filters for edge detection. In other words, the filters act as a feature detector, where the feature is an edge. Alternatively, you could compose a different filter that is activated on the corners or that is activated when there is no change in the color value.

The filters that we have used act on a single-channel image and have two dimensions; ...