Invariant texture features
Show which of the listed texture features is invariant under a change of the scale, rotation, and a change of the brightness of the image:
1. Variance operator: (G − BG) 2
2. Local gray value histogram computed in a certain neighborhood
3. Local histogram of the first-order derivative in x direction
4. Magnitude of the gray value gradient
5. Angle of the orientation vector
6. Coherency of local orientation
7. Variance of the angle of the orientation vector
Is it possible to make the features, which depend on the brightness of the image, invariant against brightness changes? If yes, how?