Degraded Image by Film-Grain Noise

[smaster]

Hello,
on my internet sessions i found a real impressive image restauration,
but without a explanation (only a small hint: Restored by adaptive window median filter):

look at the end of the site (OTHER EXAMPLES OF RECOVERING INFORMATION HIDDEN IN IMAGES):

http://www.ssp.ece.upatras.gr/galats...ESTORATION.htm

does anyone know HOW TO subract the noise correctly?
I tried to poduce a second image where only the white noise is left (with the Tone Curves) and subtract as a upper layer from the original in "subtract"-mode...when i try in photshop i could achieve some improvement, but far away from the last image of this site.

[smaster]

89 views and , and no ideas ?
should i better ask on a mathlab forum for this master piece?
(i am a bit scared, because i have no higher math skills )

greetings

[rco]

Hi smaster, It's a fake! Ha ha thats a fine piece of noise reduction. No idea how it's done but i'd love to get my hands on that program.

[smaster]

hello,
no it is not a fake, it is just damn good :-) I tried to reproduce, and I got an inkling that it is possible. The Problem is i dont know exactly how, i guess it is some sort rarly known of mathematical method.
(unlike the deconvolution, the most people/newbies dont know about it)

The Problem is the greek professor which has done the image is dead,
so i cant ask him :-(

greetings

[chillin]

It could be fake or not, I use sometimes ImageJ's Anisotropic Diffusion 2D filter with some good results, but on a pic with much lighter noise.
Here is a link to a gif file showing a progression after every 25th iteration up to 200.

[smaster]

Ah thx :-)
you brought me a bit nearer to the secret, i know imagej and your idea is nice.
But the real good about your post is, i got the idea to just add imagej to my previous google search (imagej adaptive window median filter) and BAAAM ;-)
some useful methods:
http://www.wseas.us/e-library/confer...rs/489-152.doc
http://imagejdocu.tudor.lu/lib/exe/f...shop3d2010.pdf
http://www.ljll.math.upmc.fr/Journee...ogka_jgp11.pdf
http://rsb.info.nih.gov/ij/plugins/h...et-filter.html
maybe also useful:
http://rsb.info.nih.gov/ij/plugins/hybrid2dmedian.html
http://rsb.info.nih.gov/ij/plugins/w...nc-filter.html

so thank you for this little but very helpful keyword :-)

here are some more but german only:
http://www.rst-software.de/dbv/DBV-Buch2.PDF
http://www.rst-software.de/dbv/DBV-Buch3.PDF
http://www.rst-software.de/dbv/DBV-Buch1.PDF


i have not the time yet but i will read and try to reproduce
the image, so when you look at the documents -
there are some scientific methods which could do some real magic :-)