Matrix Representation of Linear Systems Relationships
The degradation model expression looks simple.
However, a direct solution of this expression to obtain f is a monumental processing task for images of practical size.
For example, if M = N = 512, H is of size 262,144 x 264,144.
To obtain f directly would require the solution of a system of 262,144 simultaneous linear equations.
Fortunately, the complexity of this problem can be reduced considerably by taking advantage of the circulant properties of H.