The Moving Picture: The Art of Video Noise Removal
Posted May 26, 2006

All writers get queries from readers who are attempting to fix one problem or another, and it always feels great when you can actually help them out. This column describes one such occurrence, relating to a noisy HDV frame grab. While on the subject of noise removal, I'll also discuss a tool I used to remove noise from video shot at a recent concert.

I frequently use frame grabs for DVD menus or labels, though with their smaller lenses and CCDs, camcorders handle low light less adeptly than the average digital SLR, which translates to noise that detracts from image appearance. This was the problem that a reader complained of in an email last month, so I requested the image and went to work.

I started with Photoshop, which did a great job removing interlacing artifacts from the image. However, the image was speckled with chroma noise, which Photoshop's Reduce Noise filter didn't eliminate. I hunted around for noise reduction features in Ulead PhotoImpact, but found no help. A friend had recently recommended Noiseware Professional, a noise reduction plug-in that supports a number of image editing programs, including PhotoImpact and Photoshop. So I downloaded the tool from www.imagenomic.com and tried it in both programs.

You start by choosing a "setting" which ranges from artistic looks like Portrait and Film Grain Effect to corrective settings like "Full noise reduction." After choosing a setting, you can further customize operation by focusing noise reduction on shadows, midtones, or highlights, or across different colors (reds, yellows, etc.) or by boosting noise-reduction levels.

You click on a preview window to see before and after views, and once you find the appropriate settings, you can save them for use with multiple images shot under the same conditions. I fiddled with the settings a bit, and then settled on the Default settings, which removed virtually all the speckling with only a slight loss of detail. Though this is going to sound like an infomercial, here's the actual response I got back from the reader when I sent him the corrected image: "Wow! That Noiseware Pro did a great job reducing the noise."

Note that you can download free trial versions of Noiseware ($49.99) and Noiseware Pro ($69.99), though the trial version inserts a visible grid in the image after applying the filter. Or, you can download Noiseware's Community Edition 2.5, which is a free standalone version that provides all presets and most customization options.

The second problem is more complicated and costs more to fix. All of us have shot video under low-light conditions and it can be incredibly frustrating. If the location lighting is inadequate, and you can't add more, the video will be noisy and grainy even if you do a perfect job with every aspect of the shoot.

Such was the case with a recent concert I shot at the Rex Theater here in Galax. I had an all star lineup of cameras and some talented shooters to drive them. The performer was jazz singer (and international star) René Marie who had brought her own sound team, which produced awesome audio. Conditions were ideal for a great shoot except that every other stage light was blown and the producer insisted on a red gel in the spot lights to increase the "warmth" of the concert.

The VX2000 capturing DV video from stage left produced the best-looking image, while the FX1 on right, capturing HDV, showed slightly more grain. However, the JVC GY-HD100 and Canon XL H1 shooting HDV video at high magnification levels from the back were grainier still.

Using Premiere Pro's new Fast Color Corrector for the FX1 and VX2000, and the Three-Way Color Corrector for the back cameras, I removed more red from the videos than a bucket load of Visine. Early on I produced a test DVD to check quality on different television sets, and noticed that while the video was clear and artifact-free, it was covered by a fine patina of noise, which was more noticeable on shots from the cameras in the back.

This left me with two choices. I could try to convince René that it was snowing in the Rex that day, or attempt to remove the noise. Choosing the latter approach, I recalled an After Effects plug-in called AlgoSuite that I had recently tested for another magazine. The focus of my review was scaling between DV and HDV resolutions and also high quality de-interlacing, and the product had excelled at both tasks.

I also tested AlgoSuite's noise-removal function, but only as it related to the ability to improve the quality of highly compressed streaming video, not video bound for DVD. Checking the product documentation, I read that the product's Multiple Type Noise Reduction (MTNR) filter was specifically designed to remove film grain, low-light noise, and compression artifacts, and used adaptive techniques to distinguish between true noise and actual motion, removing the former and preserving the latter.

 This all sounded promising, so I filtered some footage and compared the results to the original. The filter performed as advertised, adjusting to the various noise levels from the respective cameras, and visibly reducing noise without adversely affecting image detail. For my project, it made all the difference in the world.

If you have similar problems with any of your videos, AlgoSuite is worth checking out at www.algolith.com. The entire suite costs $1,185, but you can purchase just the noise reduction functions for $395. Alternatively, for occasional jobs, you can license the entire suite for $59 per week. Budget plenty of processing time, however, as AlgoSuite is incredibly slow, taking 4:34 (hours:mins) to process 45 seconds of video on a dual 3.06GHz Xeon Dell workstation.

If you'd like to see before-and-after samples of my clips using these noise reduction tools, visit www.doceo.com/noisereduction.html.