Used Filters:

• Gaussian filter (20 different sigma) = 20 feature dimensions
• Sobel filter (1 sigma) = 1 feature dimension
• Gabor filter (1 theta, 2 different sigma, 2 different frequencies) = 4 feature dimensions
• Mean filter (5 different sizes) = 5 feature dimensions
• Hessian filter (1 sigma) = 3 feature dimensions (one for derivative in direction xx, one for derivative in direction xy and one for derivative in direction yy)