Noise, Grain and Artifact Reduction Software
Digital images shot in low light or with a high ISO setting are often very grainy, with flecks of color "noise" in areas that should have smooth color. Many software products are designed specifically for reducing this digital noise. In addition, many of the tools here can be useful in reducing or removing artifacts from too much JPEG compression.
AbsoluteDeNoiser (Java)
[Standalone] "AbsoluteDeNoiser is an easy to use software that produces very competitive noise reduction filtering for digital images. It is a Java software that should run on almost every machine: Windows 98/2000/XP, Mac OS X, Unix, Linux."
Digital GEM (Win/Mac)
[Plug-in] "Automatically reduces and manages noise and grain in digital images from any source without causing excessive softening or blurring. The Digital GEM plug-in allows users to isolate noise/grain in both highlight and shadow areas and provides a 'clarity' slider to either sharpen or soften the overall result." $79.95 US.
Jpeg Enhancer (Win)
[Standalone] Recover images damaged by low-quality JPEG compression. Remove "JPEG artifacts" and "blotchy look" from over-compressed JPEG images. Freeware
Neat Image (Win/Linux/Unix)
[Standalone] "Neat Image is a digital filter designed to reduce visible noise in digital photographic images. Neat Image detects the noise, analyzes and removes it... works in all versions of Windows, under Wine in Linux and other i386 flavors of Unix, in a PC emulator on Mac (a native version is under development)." Available in a home edition and professional edition.
NoiseFixer (Win/Mac)
[Plug-in] Remove 'noise' or 'graininess' from images. US$27.
PictureCode Noise Ninja (Win)
[Standalone] "Quickly remove high-ISO noise, scanner noise, and grain from digital images." Home version - US$29, Pro Version US$69.
Quantum Mechanic (Win/Mac)
[Plug-in] Quantum Mechanic Pro and Quantum Mechanic Lite are Adobe Photoshop filter plug-ins that reduce digital camera noise and artifacts in photographs taken by many professional digital cameras.
Noise Reduction Tool Comparison
Michael Almond has compared several noise reduction tools to find the best one. You can see samples of the results for (currently) 18 different products.