By Russ Burden – TakeGreatPictures.com
All digital cameras introduce noise into a capture. Factors that contribute to the amount are ISO, length of exposure, underexposure, size of the sensor, and how much cropping is done to the file.
- The higher the ISO, the more noise.
- Exposures of two seconds and longer introduce noise.
- If a digital capture is underexposed, corrections in post processing introduces noise, especially in the shadow areas.
- The smaller the sensor, the more noise.
- The more a file is cropped, noise becomes more of an issue.
Noise comes in two forms – Luminance noise and Color noise. Luminance takes on the appearance of film grain while color noise appears in the form of odd looking rainbow colored speckles. Both detract from the overall quality and appearance of a photo. Thankfully there are software programs that circumvent these effects. My “go to” is Nik Dfine 2.0. It’s so good at what it does, the majority of time I let the program run the Automatic feature and simply click OK.
If a slide is scanned, reducing noise is a bit trickier as film grain is viewed as noise and is quite noticeable. This is when I take advantage of the Control Point or Color Range technology. Regardless of which method is used, the amount of reduction of luminance and color noise can be finessed from 0% up to 200%. Adjusting the amount based on color, texture, exposure or a combination of all three allows me to finesse very specific areas of the image to provide the exact rendering of noise reduction I desire.