Hands-On Image Processing with Python

Edge detection with the Marr and Hildreth's algorithm using the zero-crossing computation

Computing the zero-crossings in the LoG-convolved image (to detect edges as a binary image) was proposed by Marr and Hildreth. Identification of the edge pixels can be done by viewing the sign of the LoG-smoothed image by defining it as a binary image. The algorithm to compute the zero-crossing is as follows:

1. First, convert the LoG-convolved image to a binary image by replacing the pixel values by 1 for positive values and 0 for negative values
2. In order to compute the zero-crossing pixels, we need to simply look at the boundaries of the non-zero regions in this binary image
3. Boundaries can be found by finding any non-zero pixel that has an immediate ...