Re: [SIP-devel] function pifilter

[Ricardo F. <rf...@if...>]

On Thu, 18 Dec 2003, DRUEL Jocelyn wrote:

> Hi,
> Still working on phased images (and phase unwrapping), I coded this pi filter
> to get a better unwrapping on poor quality images: it does not smooth the
> phase jumps: it just smooths what's between.
>

Hello,

I have included your pifilter function into SIP-dev, it is working
fine.

It is interesting that I tested the function on natural luminance images
messed up with imnoise, option "salt & pepper".
The result is quite good, because the edges are preserved, more
so than median filtering, although some noises are not fully eliminated.

The idea of treating a normal intensity image as a phase image seems
to makes sense in this case. The pi filter will do an adaptive blur
of the image, with the blur strength somewhat inversely proportional
to the variance of the data around the mean. The most abrupt
variation, the weaker the blur. A variation from maximum to minimum
distributed along the neighbourhood of a pixel will not blur the
pixel.

If you think this makes sense, the function pifilter will be useful not only for
photonics images, but for many other noisy images.

thanks again for contributing,
Ricardo.

--
  Ricardo Fabbri, Cybernetic Vision Research Group, USP, Brazil.
  www.rfabbri.kit.net