Reducing Digital Noise with PhotoShop
Recently, I watched a tutorial on using channels in PhotoShop. One of the neat things that I found was using channels to reduce color noise. My wife’s superzoom is a Panasonic 10 Megapixel camera, makes nice photos, but even at 100 ISO, there’s quite a bit of noise. At 200, it looks pretty nasty to my eye, especially in smooth color areas like the sky in the above image.
By opening the channels window, and looking at each color channel in PS, you can see the noise in each of the three. In the image, red was nasty, green not bad, and blue, somewhat inbetween. So, with the red channel showing, I went to filters/blur/surface blur, which has sliders for radius and threshold. Surface blur tries to keep edge detail, so it mostly affects areas of solid color. Experimenting with the settings I found that I could use a radius of 12 and threshold of 21, without losing much detail, while smoothing the nasties in the sky wonderfully. The green setting was much lower, and the blue was roughly in between. From the before and after 100% crops, you can see what a difference it made!
If you have a noisy picture, try this, it’s easy and effective!