An implementation of the Sobel operator for edge detection in images. Below there is an example of taking the first image and having the calculated image bellow.
sobel file_in file_out 123x456 [-i file_h_out file_v_out] [-g file_gray]
The file_in and file_out arguments are, obvious, the file for which the contour should be calculated and the file with that calculated contour, respectively. The third argument is the size of the image (width x height). It is needed because the RGB file type does not contain any meta information about the image it self.
The optional arguments are:
-i - Generate intermediate files with the result of the vertical and horizontal operators.
-g - Generate the gray scale file.