Noise comes in three types or patterns:
1) Random noise 2) Fixed-pattern noise 3) Banding noise
Noise often has two components—brightness and color:
4) Image noise 5) Luminance noise 6) Chrominance noise
Knowing the type and kind of noise produced will help guide you to solutions to reduce it. There are three types of noise: random noise, fixed-pattern noise and banding noise.
Dave McDonell, cofounder of Imagenomic, the company that makes Noiseware, my favorite noise reduction software weighs in on noise.
JPC Where does noise come from?
DM There are several factors in a digital camera capture process that contribute to noise. The most prevelant are temperature, the actual capture circuitry, sensor size, and the process of sub-sampling which induces errors between adjacent pixels.
JPC Why is chrominance noise so much easier to reduce than luminance noise?
DM It’s really not in application. It’s just that you perceive changes in luminosity or brightness much easier than you do in color.
JPC Fine color noise is easier to reduce than coarse color noise, like the color patterns created by demosaicing bayer patterns. When are you most likely to encounter this type of noise? How should you treat it differently? How far can you go?
DM There are no hard and fast rules for any of the above questions as all are dependent on the capture situation and subsequent output medium.
Here’s an excerpt from my column in the current issue of Digital Photo Pro.
“When adding noise to digital files, keep noise separate from the image so you can control both independently of one another. This way you’ve got extraordinary control and flexibility. When noise is placed on its own layer you can eliminate or change it at any time in the future, reduce its opacity, localize it, desaturate it, target it into specific channels, move it, scale it, blur it and much more …”
Read more in the current issue of Digital Photo Pro.
Learn out more in my digital printing workshops.