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4/22/2019 5:32:20 PM
Posted: 4/16/2007 5:10:31 PM EDT
I was reading some reviews for the Samsung NV7, and several of the reviews mention excessive noise in the pictures. So I was wondering what exactly noise is?
Link Posted: 4/16/2007 5:53:57 PM EDT
There are a number of sources of noise contamination.

Heat generated might free electrons from the image sensor itself, thus contaminating the "true" photoelectrons. These "thermal electrons" give rise to a form of noise called thermal noise or dark current.

Another type of noise is more akin to the 'grain' obtained by using a high ISO film. When we use a higher ISO, we are amplifying the signal we receive from the light photons. Unfortunately, as we amplify the signal, we also amplify the background electrical noise that is present in any electrical system.

In low light, there is not enough light for a proper exposure and the longer we allow the image sensor to collect the weak signal, the more background electrical noise it also collects. In this case the background electrical noise may be higher than the signal.
Link Posted: 4/18/2007 5:45:51 AM EDT
That's pretty much on target. The downside to digital noise is that unlike film grain, it's not uniform.
Link Posted: 4/18/2007 9:28:24 AM EDT
Does anyone have an image that would show how noise affects pictures?
Link Posted: 4/18/2007 11:09:57 AM EDT
Link Posted: 4/18/2007 2:31:22 PM EDT

Originally Posted By ilikelegs:

Originally Posted By unclemoak:
Does anyone have an image that would show how noise affects pictures?

This is a link to a high res image I shot at 1600 ISO.
You can see the noise in the darker areas of the crowd.


Image will take a while to load.

Just out of curiousity, what resolution of camera was that shot with?
Link Posted: 4/18/2007 6:18:06 PM EDT
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