Noise Ninja(www.picturecode.com) claims an effective two-stop improvement in image quality, meaning your ISO 1600 images have the noise of ISO 400. It’s available as a plug-in for Aperture, Lightroom and Photoshop. List Price: $79 (Full Version).
Neat Image(www.neatimage.com) is available as a stand-alone Windows program or as a plug-in for both Photoshop and Aperture. Users have created an ever-expanding profile library, making the program particularly powerful right out of the box. List Price: $79 (Pro Version).
Noiseware(www.imagenomic.com) is an app that learns as it works. Every time you filter an image, the software understands more about the noise created by your camera or scanner, automatically refining future noise-reduction results. It’s available as a Photoshop plug-in or standalone program. List Price: $69 (Pro Version).
Nik Dfine(www.niksoftware.com), available for Aperture, Lightroom and Photoshop, is designed for photographers who want highly selective and customizable noise-reduction control for different types of noise in selected image areas. List Price: $99.
Topaz DeNoise 5(www.topazlabs.com) integrates with Photoshop, Aperture and others, and attempts to retain maximum image detail while smoothing out the noise. DeNoise 5 can provide up to the equivalent of four stops of improvement, making an ISO 1600 image look more like one shot at ISO 100. List Price: $79.