Slashdot Mirror
Open Source Image De-Noising
GREYCstoration is an open-source tool able to de-noise, inpaint, or resize 2D color images. This is a command-line program developed by the IMAGE team of the GREYC Lab in France and is available for Unix, Mac, and Windows systems under the CeCILL license. The algorithm is based on anisotropic diffusion partial differential equations. These equations are able to smooth an image while preserving its main structures. The demo page presents interesting examples of color image de-noising and reconstruction. This is a serious free alternative to commercial products like Noise Ninja or Neat Image that perform the same kinds of operations. The tool is still a little bit hard to use (command-line based), but I hope the simple C++ API will ease the integration of the algorithm in more user-friendly interfaces. Previous versions of GREYCstoration are already available in Digikam and Krita.
Another great free tool is called Picture Cooler. It rivals or exceeds Noise Ninja for certain images. Download it here: http://denoiser.shorturl.com/
. size.matter/
But if you want images with less noise, try and buy a camera with a larger sensor. dSLR's have large sensors as do many Fuji cameras including their tiny P&S models. Most sensors on subcompact P&S cameras measure only 5.76x4.29mm (1/2.5"). Many of the smaller cameras by Fuji use a 1/1.8" sensor that measures 7.18x5.32mm.
A nice explanation of noise and sensor size is here: http://www.clarkvision.com/imagedetail/does.pixel
This tool looks very cool, but today's semi-pro and pro (and even some consumer grade) cameras will store their images in a raw format which preserves 12 bits per color channel at a minimum.
GIMP can't deal with these. Tools such as ufraw can convert them to 8 bits/channel images such as JPEG but don't allow you to actually manipulate the image in its native color resolution.
Linux seriously needs a good image manipulation tool such as the GIMP with 16-bit or even 32-bit per color channel support built-in. This is particularly important for operations like sharpening.
Cinepaint will do it but it's way behind in features compared with GIMP these days.
What's the hold up with GIMP anyway? You'd think its developers would take this kind of issue seriously and would fix the engine to natively do, say, 32 bits per color channel internally.
Use 'slashdot stuff' in the subject line in any email you send me if you want to get past the spam filter.
is a pretty good algorithm. We use it for MRI images. The biggest problem is setting the parameters. Fortunately it's an embarrassingly parallel algorithm so I wrote a version that will run realtime on a video card. It's pretty cool to move the slider and watch the noise fade away, move it further and some of the edges blur, further and you start to lose the image.
The lower ISO you can get the more detail you could capture given that other parameters are fixed. Have you ever shot with Velvia ISO 50 film? -- it creates stunning details. I think Fujifilm discontinued it last year or so. In film the lower the ISO the finer the grain. As far as digital is concerned think of ISO as sensitivity of the CCD. You can turn the gain up to ISO 3200 but you will amplify a lot of noise too.
It can also take one image and repaint it in the style of another image, so you can take a black and white photo and a pencil sketch as inputs and end up with your photo rendered using parts of the pencil image which are similar in form.
Another trick it can pull is creating tileable textures from any image. Sometimes the results are a little surprising if you start off with a picture of people at a party but they are totally seamless.
It comes as a GIMP plugin and is easy to use if you are used to the GIMP.
Anything I post is strictly my own thoughts and doesn't necessarily have anything to do with the opinions of IBM.
TFS: "GREYCstoration is an open-source tool"
"A witty saying proves nothing." - Voltaire
If you're experiencing a lot of noise at ISO400, it's time for a new camera.
Also, in response to your later post, what many DSLRs do for long exposures (usually taken at night and with high ISO and experience a lot of noise in the black areas) is to take another exposure immediately after the first one, but with the shutter closed. Then, the camera knows where the sensor noise is and can subtract it from the actual picture.
So if you take an 8 sec. exposure and your camera freezes up for the following 8 sec, you'll know why.
"Avoid employing unlucky people - throw half of the pile of CVs in the bin without reading them." -- David Brent
In fact, there already exists software for that purpose: ALE. And it is open-source too!
They should also use real, not artificial, noise.
Check out very impressive clean up of a PDA camera. That's good. Ordinary smoothing filters blur important details, like those in the watch or the baby's ear. How nice that it is already in Digikam, one of the easiest to use photo managers out there.
Friends don't help friends install M$ junk.
I too have a fridge full of film (Velvia, Astia, Provia), however I accept that I'm a dinosaur and proud of it! Modern digital SLRs perform better than 35mm film in practically every respect and challenge medium format in quality. Only with large format is that not true - and large format is something of a niche! Soon of course even this will bow to the digital revolution.
I suspect she's like me, stuck in the past and quite happy to stay there for the time being! There's still something magical about transparency film. The colour reproduction is very special, with a gamut wider than you can sense in either prints or monitors. Although the gamut of modern digital sensors is just as good, there's no way of actually sensing it, as the display devices aren't up to snuff! Wide gamuts make an enormous difference to an image. The colors you see in nature are far more diverse than those that can be reproduced in print or on a computer screen. It's only by actually seeing these things first hand that one can appreciate the difference, prints look strangely grey an lifeless in comparison.
Ah, transparency film!
I'll stop evangelising now - I'm probably preaching to the converted anyway!
Be nice to people on the way up. You will meet them again on your way down!