[Digikam-devel] New image editor noise reduction plugin...

[Caulier Gilles]

Hi all,

I have recently backported the new despeckle algorithm from gimp 2.2.x to 
digiKam like noise reduction tool with support of 16 bits images.

After to have played with it, i have been unsatisfied... The result are a 
little bit strange, especially with recursive option.

After to have serching on the web the best NR technics, my conclusion is that 
this algorithm is a wrong way. despeckle use RGB color space to fix noise and 
this is a wrong issue. 

After to any investigation, i have found a great GPL plugin tool named 
dcamnoise2. The code is really impressive and very well documented...

I have backported the code this week end, and the result look great :

http://digikam3rdparty.free.fr/Screenshots/new_noisereduction_plugin.png

The only one NR tool that i have already used witch provide a similar result 
is Noise Nija plugin for photoshop... If you want to test it, there is a diff 
file against current NR tool implementation from svn trunk here :

http://digikam3rdparty.free.fr/misc.tarballs/nr.diff

To test it, just go to digikamimageplugins/noisereduction directory, and apply 
it like this:

# diff -p0 < nr.diff

make, and install the plugin. You can play with it in digikam. There are some 
noisy images to use here :

http://digikam3rdparty.free.fr/Images_2_Test_DImg/NOISE/

To use it, especially with parameters, I recommend you to read the comments of 
the algorithm author from the original gimp plugin source code here :

http://digikam3rdparty.free.fr/misc.tarballs/dcamnoise2-0.63.c

Nota : 

- The most important settings are in General tab.
- The plugin do not support yet 16 bits images. It's just a question of time. 
I will do it later, if the fedback is right from digiKam users.

Please, let's me hear your viewpoints. Thanks in advance...

Gilles Caulier