Open an image in Noise Ninja. Click on the "Load Noise Profile" icon and select the desired file, such as "DSC-F828 ISO 400" for an image made with a Sony Cyber-shot DSC-F828 at ISO 400. Click on the "Noise Filter" selector button to access a new software screen that includes a wide range of tools for tweaking the extent of noise reduction and sharpening. Ignore these options initially. In order to evaluate the effect that the noise reduction software will produce, click your mouse pointer on an important area of the image. A rectangle will appear. The image area inside the rectangle provides a preview: it should be noticeably smoother than the surrounding area.

If the preview area appears to be unnaturally soft, or if noise is still excessive, check out the available tools. All of these are discussed in detail in the "Tutorial" pdf (Acrobat) file that's provided with Noise Ninja 2.0. I found the "Strength" control in the "Luminance" group to be the most useful; this tool allows for moderating or increasing the aggressiveness of the noise reduction filtration. Avoid selecting an excessive level that eliminates texture. Like film grain, slight digital noise is quite acceptable (or desirable) especially in subject areas that are textured.

Note: The controls in the "Luminance" group affect filtering of noise in the brightness component of an image; that's where most real data is located. The tools in the "Colors" group are used to adjust the filtering of color noise, which is often the most annoying. A full range of "Color Specific" filters are also available. These allow for increasing or decreasing the filter strength selectively: for particular colors, such as wide stretches of green foliage or a blue sky.

Evaluation: The pre-defined noise profiles were created for generic settings for in camera sharpening and other parameters. They produced very good results with 75 percent of my test images; slight tweaking brought them close to perfection. The remaining images required greater adjustment and experimentation to achieve just the right balance of smoothness without producing an artificial effect.

A small portion of a full image that exhibits objectionable color noise, Photo A illustrates a worst-case scenario. After extensive experimentation with Adobe Raw in Photoshop CS I was able to achieve only acceptable results (Photo B). Noise Ninja 2.0 produced a cleaner image (Photo C) while maintaining good detail and a natural effect.

Other Noteworthy Options
If your digital camera is not covered by the noise profiles that are available, you'll want to create a custom profile series for your camera's various ISO settings. Even if a profile is available, take advantage of this capability for the best possible results for all images, with the least need for personalized "tweaking." Start by downloading a calibration chart (an optimized target) from the website. Open the JPEG file, print it, and photograph it at several ISO settings. (You can also create custom profiles for specific scanner/film combinations.) Load each chart photo into Noise Ninja, and follow the instructions provided in the Help menu; these will become your own custom profiles.

Regardless of the profiles that you use, or the amount of tweaking, some of the filtered images will not be perfect. In that case you can use the "Undo" control to return to your original image and start again. Or try another option, the "Noise Brush": a tool that can be useful for "post-filtration" adjustment. This brush allows for selective fading (moderating) of noise reduction in specific areas where the filtration was too aggressive. It's most useful for restoring detail in textured areas of an image or in a person's hair in a portrait photo.

Evaluation: If you frequently shoot images that require noise reduction, it's well worth building custom profiles to minimize (or eliminate) the need for adjustments on subsequent images. The process takes about 10 minutes per profile. For occasional use of Noise Ninja 2.0, the steps discussed in the Advanced section work very well.

Final Assessment
Photographers who shoot with a digital camera's raw capture mode may not feel any need for after-market noise reduction software. After all, most raw converter programs already include tools designed for the same purpose. If you fall into this category, experiment with the free trial version of Noise Ninja 2.0, using the appropriate pre-defined camera/ISO profile. Compare the effectiveness of your raw converter's noise reduction system vs. Noise Ninja.

My own tests, using "Luminance Smoothing" and "Color Noise Reduction" in Adobe Raw in Photoshop CS, were quite revealing. After some experimentation to find the right settings, CS produced very good results with moderately "noisy" images. I then converted the same images to TIFF, without noise reduction, and used the advanced features of Noise Ninja 2.0. My images are just as "clean" but appear more natural, with a bit of "bite" for a less plastic look. With images exhibiting prominent color noise, Noise Ninja 2.0 won hands-down because of its uncanny ability to suppress the colored specks without producing excessive smoothness. Regardless of the settings used in Adobe Raw, I was simply unable to produce satisfactory results with such images. Naturally, your own test results may differ, depending on the type of noise in your images, and the raw converter software that you use.

Although Noise Ninja 2.0 offers a more convenient interface than the earlier version, it's not intended for those who want a single-click solution to digital noise reduction. Still, the new program is quite intuitive in operation and the selection of an appropriate noise profile is certainly not complicated.

Spend 30 minutes studying the tutorial, plus an hour experimenting with the various controls, and you should become quite competent in using the most important features.

And the bottom line on Noise Ninja 2.0? This very versatile program is remarkably successful in moderating digital noise, while maintaining excellent color saturation, contrast, and fine detail. It's far more effective than Photoshop's "Despeckle" feature, a tool that appears to have little effect except making images appear soft. If you frequently shoot at high ISO settings, or own a camera that often generates noisy images, the $29 investment will pay generous dividends, helping to improve the technical aspects of your digital photos.

At this time, Noise Ninja 2.0 is free-standing software compatible with Mac OS X 10.2 and 10.3 and with Microsoft Windows 98/Me/2000/XP. In the future, a version will be available as a Photoshop plug-in, for more convenient workflow. The software is available as a download from www.picturecode.com for $29 for the Home edition (8-bit TIFF output) and $69 for the Professional edition (16-bit TIFF output; allows for batch processing and multi-processor execution). Licensed users of prior versions can upgrade to Version 2.0 at no charge.

A long-time contributor to "Shutterbug" and "eDigitalPhoto," stock photographer Peter K. Burian is the author of a new book, "Mastering Digital Photography and Imaging" (Sybex). Covering the relevant technology, equipment, and techniques, this book provides 270 pages of practical advice.