Digital Noise Reduction in GIMP
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| Digital Noise Reduction in GIMP | Alex Fernandez | 24 Aug 13:16 |
| Digital Noise Reduction in GIMP | Jakub Steiner | 24 Aug 15:22 |
| Digital Noise Reduction in GIMP | Hal V. Engel | 24 Aug 18:26 |
| Digital Noise Reduction in GIMP | Jean-Luc Coulon (f5ibh) | 24 Aug 20:55 |
| Digital Noise Reduction in GIMP | Alex Fernandez | 25 Aug 11:14 |
Digital Noise Reduction in GIMP
Hi list,
I'm interested in noise reduction using GIMP. A little (skippable) background first.
I recently bought a digital camera, a very nice Canon IXUS 40. One big plus over traditional "chemical" photography is that you can change sensitivity for poor light conditions. However, this increases noise in the resulting image. Digital noise tends to be uglier than its analog counterpart, I'm not sure why; maybe we will get used to it eventually, or maybe not.
In the meantime, digital noise is quite annoying. Since the picture is already in the computer, I tried to GIMP the noise off, but had no luck. People seem to use "unsharp mask", but the results are frankly quite poor. I have found several programs that seem to do the trick more or less, but all of them proprietary and all of them for Mac / PC (I'm on Linux). Of course, none work with GIMP.
So after many offroads (like improving on Remi's excellent FFT plugin), and being of the geek persuasion, I tried to create my own GIMP plugin. It has been a very interesting process, and results are not bad even at this preliminary stage. I have used several algorithms (stdev discrimination, linear regression); right now I'm trying out a combination of median and interquartile range which is promising, but still not perfect.
Now, let's go to the questions.
- Is there a noise reduction technique / plugin for GIMP that I haven't found?
- Where can I upload the result of my own efforts so that people can
try it out or even improve it?
- Do you know any algorithms that work really well for noise
reduction? I came across this message:
http://www.mail-archive.com/gimp-developer@lists.xcf.berkeley.edu/msg08651.html
so if someone can point me to the paper mentioned or similar, I
would be most grateful.
Thanks,
Alex.
Digital Noise Reduction in GIMP
On Wed, 2005-08-24 at 13:16 +0200, Alex Fernandez wrote:
- Is there a noise reduction technique / plugin for GIMP that I haven't found? - Where can I upload the result of my own efforts so that people can try it out or even improve it?
Hi Alex,
unsharp mask you mention is generally used for sharpening, which tends
to actually increase the visibility of noise. Some techniques for
getting rid of noise are described on the gimp website -
http://www.gimp.org/tutorials/Reducing_CCD_Noise/ http://www.gimp.org/tutorials/Selective_Gaussian_Blur/
I have recently found an interesting way to get rid of RGB independent noise - http://jimmac.musichall.cz/weblog.php/Photos/RGBNoise.php, but weren't so lucky in replacing the median filter with gimp's despeckle. In the end, selective gaussian blur is what works for me best.
The place for 3rd party gimp plugins and scripts is registry.gimp.org, it includes a few noise removal gems.
cheers
Digital Noise Reduction in GIMP
On Wednesday 24 August 2005 06:22 am, Jakub Steiner wrote:
On Wed, 2005-08-24 at 13:16 +0200, Alex Fernandez wrote:
- Is there a noise reduction technique / plugin for GIMP that I haven't found? - Where can I upload the result of my own efforts so that people can try it out or even improve it?
Hi Alex,
unsharp mask you mention is generally used for sharpening, which tends to actually increase the visibility of noise. Some techniques for getting rid of noise are described on the gimp website -http://www.gimp.org/tutorials/Reducing_CCD_Noise/ http://www.gimp.org/tutorials/Selective_Gaussian_Blur/
I have recently found an interesting way to get rid of RGB independent noise - http://jimmac.musichall.cz/weblog.php/Photos/RGBNoise.php, but weren't so lucky in replacing the median filter with gimp's despeckle. In the end, selective gaussian blur is what works for me best.
The place for 3rd party gimp plugins and scripts is registry.gimp.org, it includes a few noise removal gems.
cheers
You might give the GREYCstoration plug-in a try. It also installs a standalone command line program that can do noise reduction to 16 bit images. The controls are not well documented and I have found that values that work for me are MUCH different from the values that the controls default to. Also the preview in the plug-in is next to useless. But once you figure out what setting work best it is a very powerful tool.
Hal
Digital Noise Reduction in GIMP
Le 24.08.2005 15:22:45, Jakub Steiner a écrit :
On Wed, 2005-08-24 at 13:16 +0200, Alex Fernandez wrote:
- Is there a noise reduction technique / plugin for GIMP that I
haven't found?
- Where can I upload the result of my own efforts so that people
can
try it out or even improve it?
Hi Alex,
unsharp mask you mention is generally used for sharpening, which tends to actually increase the visibility of noise. Some techniques for getting rid of noise are described on the gimp website -http://www.gimp.org/tutorials/Reducing_CCD_Noise/ http://www.gimp.org/tutorials/Selective_Gaussian_Blur/
I have recently found an interesting way to get rid of RGB independent noise - http://jimmac.musichall.cz/weblog.php/Photos/RGBNoise.php, but weren't so lucky in replacing the median filter with gimp's despeckle. In the end, selective gaussian blur is what works for me best.
The place for 3rd party gimp plugins and scripts is registry.gimp.org, it includes a few noise removal gems.
You can try gaussian blur only on red and blue channels leaving green channel untouched (it is generally less affected by noise and will help to keep a raisonably sharp image after applying the blur).
cheers
--
Jakub Steiner
Jean-Luc
Digital Noise Reduction in GIMP
Thanks a lot to everyone for your suggestions, I will let you know how it goes when I have time to try them out. I'm still open to theoretical approaches you find interesting.
The place for 3rd party gimp plugins and scripts is registry.gimp.org, it includes a few noise removal gems.
Thanks! I will upload my filter ASAP.
Alex.
