Glossary
Like any other technical procedure, noise reduction has its own jargon. Feel free to skip this section if you’re familiar with the terminology, or refer back as it becomes necessary.
Digital Noise : In digital photography, Digital Noise is the equivalent of “grain” in film-based photography. Any pattern, texture, or coloration introduced into the captured image that is caused by the sensor (or related processing) rather than the subject can be considered Digital Noise. It can also be introduced into an image by a scanner. Most noise occurs when heat or extra electric charge in the sensor causes receptors to fire when they should not. Using a high ISO setting on a digital camera allows extra power to the sensor to increase its sensitivity, but also increases the amount of heat, and consequently, the number of misfires in receptors.
Chroma Noise: Chroma Noise (also called color noise, chromatic noise, etc) is exactly that; it is colored pixels introduced into an image that cause color shifts and loss of saturation. Usually seen in deep shadows.
Luminance Noise: Luminance Noise is the most common type of digital noise and is characterized by grainy patterning caused by different luminance levels (ie, dark and light) in an area that should have had relatively even luminance levels from pixel to pixel.
High, Medium, and Low Frequency Noise:
Compression Artifacts:
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