dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Jan 21, 2009 at 08:58:25AM +0000, A Navaei wrote:
> Hi,
> 
> I am trying to use Dolfin for solving some standard image processing
> optimisation problems. Creating the corresponding equations requires
> incorporation of image data as dense matrices into the problem, here
> is an example:
> 
> http://users.fmrib.ox.ac.uk/~steve/review/review/node3.html
> 
> where Eq (4) is of interest, where the unknowns are (u, v) and I is
> the image pixel values.
> 
> A good start is to initialise the pixel values into a simplicial
> triangulated mesh. Which Dolfin classes should be used in order to
> perform this?
> 
> 
> -Ali

I imagine you could define a Function I (the image brightness
function) as either a piecewise linear function with one value at each
vertex (corresponding to a pixel) or a piecewise constant function
with one value at each pair of triangles (together corresponding to a
pixel).

So you need to overload the eval() in a user-defined function I to
return the correct values by some kind of table look-up (finding the
pixel values).

-- 
Anders

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