What does pooling mean?
Pooling is used for downsampling(降采样). For example, "max pooling" means using the max element of a n*m matrix such as 3*3 matrix. "Min pooling" and "average pooling" mean using the min and the average element of the matrix, respectively. The aforementioned example is used for a plane and it can also used for a cube.
A 30*30 matrix can be divided into 9 10*10 matrixes. Is it meaningful to use pooling for the 9 small matrixs? Maybe it is meaningless since pooling is always used for each small block(块与块之间的pooling也许没意义). This is with Haiqing's help.
What does whitening mean? whitening or sphering the data
The third paragraph of Section 2 of "ICA with Reconstruction Cost for Efficient Overcomplete Feature Learning, NIPS 2011" explains this concept very clearly. Whitening involves a PCA step. It is different from the matlab function zscore which normalizes the data with zero mean and unit variance. Why does whitening remove the second-order information, e.g. covariance and variance? The reason is that the variance is unit. In problistic, there is moment estimation(矩估计). Mean value is the first moment(一阶矩) while variance is the second-order moment(二阶矩). This is with Wei Wang's help.