Hi Jérôme,

Can you explain your problem more? You know A and x and want to find b? Is this an exact solution, or is Ax = b + err? SciPy’s sparse.linalg module is where you’ll find most of your answers, I think… If you want to *build* A from some description, you might find our homography example in Elegant SciPy useful:

https://github.com/elegant-scipy/elegant-scipy/blob/master/markdown/ch5.markdown#applications-of-sparse-matrices-image-transformations

Juan.

On 22 Nov 2017, 1:58 AM +1100, Jerome Kieffer <google@terre-adelie.org>, wrote:
Dear all,

I have an image which is "blurred" by a kernel which depends on the
position on the image.
This blurring can be expressed as a sparse matrix (A) multiplication where
only the neighboring pixels have non-null contribution.

Ax = b

where in addition
Aij>=0
x >= 0 #non negativity constrain.
b >= 0 # measured signal

Does anyone have some hints on where to start looking at ?
Thanks for your help

--
Jérôme Kieffer
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