Consider the block of 4 pixels a,b,c,d
These can be considered a 4d vector
[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.