Tag Archives: Image noise

Reducing image noise in the Canon XH A1

English: Canon Xh-A1 HDV camcorder
English: Canon Xh-A1 HDV camcorder (Photo credit: Wikipedia)

The Canon XH A1 is not very old, but it is tape-based, which today seems quaint and dated!

However, the camera shoots excellent images and its 20x zoom lens remains amazing.  Even at 1440×1080 HDV, it shoots sharper and lower noise images than most of the consumer 1920×1080 camcorders.

But when comparing to my Lumix GH-2 in daylight, the XH-A1 has some image noise that resembles film graininess. Some people actually like that – I do not. I like clean and smooth images and prefer clean over sharp.

Some tips that I have discovered may be helpful to others.

If you shoot using the default camera options, the camera applies no noise reduction strategies “out of the box”. Not surprisingly, there will be some image noise.  While each scene is going to be different, I have found that by configuring the custom presets with some noise reduction options, I get very clean imagery.

I am using the following as a starting point:

  • SHP set to -3
  • Sky Detail to set to smooth/soft
  • NR2 set to “Low”.
  • Coring set to +9

Noise reduction can be improved a bit more by setting NR2 to its medium setting, or reducing the sharpness setting a bit more. These modest changes make a very large and noticeable reduction in noise. The NR1 noise reduction option only works on imagery that is not moving or barely moving, otherwise you get “ghost trails” in the video.

You can also manually set the lowest gain setting to -3db (instead of 0 db). For DSLR shooters, the video gain setting on a video camera is the same idea as setting the ISO level. More gain is the same as higher ISO, which also implies, more noise.

I remain unconvinced that the -3db setting makes any difference in noise. It does buy an addition 2x neutral density equivalent, which can be useful in broad daylight.

For maximum sharpness, I have found (as have others) that the sharpest images occur at an aperture of around f/4.0 plus or minus.

I shoot virtually everything in manual modes, usually shutter priority Tv mode, which means I adjust the neutral density filter settings and the shutter speed to get close to around f/4.0. Much above f/5.6 and sharpness starts to degrade.  You can manually set the aperture to f/9.5 and the camera’s automatic features will go as high as f/22! Images at those aperture settings produce garbage! Incredibly soft, grainy and ugly looking – don’t do that! This is the cause of widely reported and unexplained “grainy” footage captured with the XH A1 – using far too high an f-stop for the lens and sensor. The solution is to use ND filters and shutter speed to keep the f-stop in a low range.

Using these tips you can produce some very clean and very sharp video on the XH A1. I recently did some shooting using both the XH A1 and the Lumix GH-2. If you tweak your XH A1 well, it is very difficult to tell the difference between the XH A1 and the GH-2, unless you have a gigantic HDTV. The XH-A1 shoots at 1440×1080 while the GH-2 can shoot at 1920×1080/24p and /30p, or also 1280×720/60p.

  • 1080/24p is 49,766,600 pixels per second.
  • 720/60p is 55,296,000 pixels per second.

Because of how our eyes process images over time, the higher resolution image might not appear as high to our eyes. Weird, huh?

Finally, if you have noisy images already on tape that you would like to clean up, get Neat Video (http://neatvideo.com). This product is fantastic. On my quad core processor, it can take nearly one hour to clean up a minute or two of HD video, but the results are stunning. (I think they just released a new version that may drop the time to 20 to 30 minutes per minute of HD video on my configuration but I have not installed the update yet.)

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