Exercise:Convolution and Pooling

From Ufldl

Jump to: navigation, search
(Step 3a: Convolution)
Line 120: Line 120:
These same three steps must also be applied to the convolved patches.  
These same three steps must also be applied to the convolved patches.  
-
Taking the preprocessing steps into account, the feature activations that you should compute is <math>\sigma(W(T(x-\bar{x})) + b)</math>, where <math>T</math> is the whitening matrix and <math>\bar(x)</math> is the mean patch. Expanding this, you obtain <math>\sigma(WTx - WT\bar{x} + b)</math>, which suggests that you should convolve the images with <math>WT</math> rather than <math>W</math> as earlier, and you should add <math>(b - WT\bar{x})</math>, rather than just <math>b</math> to the resulting matrix <tt>C</tt>, before finally applying the sigmoid function.
+
Taking the preprocessing steps into account, the feature activations that you should compute is <math>\sigma(W(T(x-\bar{x})) + b)</math>, where <math>T</math> is the whitening matrix and <math>\bar{x}</math> is the mean patch. Expanding this, you obtain <math>\sigma(WTx - WT\bar{x} + b)</math>, which suggests that you should convolve the images with <math>WT</math> rather than <math>W</math> as earlier, and you should add <math>(b - WT\bar{x})</math>, rather than just <math>b</math> to the resulting matrix <tt>C</tt>, before finally applying the sigmoid function.
==== Step 3b: Checking ====
==== Step 3b: Checking ====

Revision as of 22:32, 14 May 2011

Personal tools