We used Sobel Mask pairs. After finding horizontal and vertical
edges we take the absolute value of their sum. In order to do this, we
coded a function that takes two filters at the same time, convolves the
image with both mask individually and returns the specified sum
We normalize the resulting image in
order to get a better result.
Here are the convolution mask pair that
we use:
| -1 | 0 | 1 |
| -2 | 0 | 2 |
| -1 | 0 | 1 |
| -1 | -2 | -1 |
| 0 | 0 | 0 |
| 1 | 2 | 1 |