Noise reduction experiment

Started Apr 20, 2012 | Discussions thread
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Ron Tolmie
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Noise reduction experiment
Apr 20, 2012

The top photo is a noisy B&W image that has been subjected to two noise reduction steps: "One step noise removal" then "Edge preserving smooth" using Paint Shop Pro. Neither step by itself was nearly as successful as using the two together. In this example there is a large improvement in image quality at the expense of only a small degradation in sharpness.

In this experiment a B&W image was chosen so that the noise reduction only had to deal with luminance noise, not chroma noise. Moreover, much of the noise was artificially introduced by using part of an image (by coastcontact) that employed the Film Grain filter in a FZ150 camera. That meant that the underlying image was sharp, as opposed to a normal noisy (and unsharp) image that you would get with a high ISO setting.

I nearly always use noise reduction for my ZS20 images even at ISO 100 to combat noise that shows up in blue skies or shadow areas. In such cameras the pixels are so small that the number of photons per pixel varies because of quantum mechanics and that variance (noise) cannot be eliminated by improvements in the electronics. There have been big improvements in the electronics of sensors in the past few years but this particular problem can only be dealt with by post processing in the camera or in an external PP step.
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Ron Tolmie

Panasonic Lumix DMC-FZ150
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