nConsider the block
of 4 pixels a,b,c,d
nThese can be
considered a 4d vector
n[a,b,c,d] expressed
in the basis Space
Or in numbers [1,0,0,0], [0,1,0,0], [0,0,1,0],
[0,0,0,1]
The pixel
values are the results of performing inner product operations between the patch and
the pixel basis vectors which select out individual ‘dimensions’ of
the patch.