Efficient Sparse Coding in Early Sensory Processing: Lessons from Signal Recovery
Figure 4
Reconstruction quality as a function of the number of nonzero coding units and .
Reconstruction quality is measured by mean SNR: , where
runs over the inputs. Since RPCA is an additive decomposition, the reconstruction error is given as
. The total number of nonzero entries is given as the sum of the rank estimate of
and the preserved number of nonzero units (k) in the sparse overcomplete representation of the atypical part (
) of the RPCA output. Since sparseness level is automatically set by SCE, the following arbitrary values for k were chosen. For
and for
,
.