Co-occurrence matrix

The gray values ​​matrix (german gray level co -occurrence matrix ( GLCM ) or co -occurrence matrix) is an important tool in digital image processing.

Is used, the gray value matrix in the detection of textures. In an image with high contrast surface structure, the lower left and upper right corner is heavily occupied, while an image with large monotone areas has a strong main diagonal.

The matrix of the gray combinations :, where the frequency of combinations of gray and the relation between the pixels and describes.

In addition, can be adapted to the elements with the approximate length of the border between the gray value and recognize.

Example

The example is a picture with some monotonous areas and therefore has a strong main diagonal.

Image

And relation with

Yields the gray values ​​matrix

For example, to get the entry now, it counts how many times in the right neighbor of a one is a two. This occurs at the points, and on, which is exactly four times [; ;].