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Radon transform

From Biocrawler, the free encyclopedia.

In mathematics, the Radon transform in two dimensions is the integral transform

\mathcal{R} \left\{ f(x,y) \right\} = \int_{-\infty}^{\infty} \int_{-\infty}^{\infty} f(x,y) \delta(y-(mx+b)) \, dx \, dy.

The Radon transform integrates a function over lines in the plane, mapping a function of position to a function of the slope and the y-intercept.

This transform in two dimensions and three dimensions (where a function is integrated over planes) was introduced in a 1917 paper by Johann Radon, who provided formulae for the inverse transform (reconstruction problem). It was later generalised, in the context of integral geometry.

A discrete Radon transform is a Hough transform.

The Radon transform is useful in computed axial tomography (CAT scan). In the 2D case

P_m: b \mapsto \mathcal{R} \left\{ f(x,y) \right\}(m,b)

is the 1D projection of f along the direction

y = mx

and we want to reconstruct the 2D image f from all the 1D projections Pm.

A less computationally-intensive algorithm for reconstructing from the sinogram is the filtered back-projection.

See also

External link

Wikipedia (http://en.wikipedia.org/wiki/Main_Page) Radon_transform (http://en.wikipedia.org/wiki/Radon_transform) version history (http://en.wikipedia.org/w/index.php?title=Radon_transform&action=history) GNU Free Documentation Lizenz (http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License) CC-by-sa (http://creativecommons.org/licenses/by-sa/2.5/)

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