Canny edge detector

The Canny edge detector, unlike convolutional edge detection filters, produces clear and thin lines when applied to an image.
The algorithm consists of four steps:

1. Filter edges using a convolutional filter.
2. Thin edges depending on it's gradient and direction.
3. Threshold the image so all pixels where it's gradient is below a minimum threshold becomes black, all pixels where it's gradient is above a maximum threshold becomes white, and the rest becomes gray.
4. Trace the edges so all gray pixels connected to white becomes white, and the rest becomes black.

Convolutional edge detection filters design

In this post I want to talk about edge detection filters, that are a type of convolution filters, this filters are widely used in features classification algorithms. I will show you all the theory beside edge detection and how to tweak the parameters to match your needs.