Beyond ℓ1 sparse coding in V1
Fig 2
CEL0, and to a lesser extent, ℓ1/2, and hard thresholding produce sparser codes than ISTA.
A: MSE between the reconstructed and the actual image for the last 500 batches as a function of the thresholding method. B: Distribution of activity of the units for the image stimuli presented. The middle of the vertical lines represent the mean number of active units per image patch, their length the standard deviation. C: Distribution of the amplitudes of the active units D:MSE as a function of the number of active units. To get these data points we varied the λ parameter for each algorithm.