How Do I Measure Noise Using Photoshop? And What Is A Significant Change?

Started 2 months ago | Discussions thread
57even Forum Pro • Posts: 14,111
Re: Off-topic Nerdy Dark Current Discussion

decaf14 wrote:

I think that dark current still varies with time but I'm getting outside my expertise here. Please correct me if my understanding is mistaken as I'd like to learn more.

"Dark current noise is the constant current that exists when no light is incident on the photodiode. This is the reason it is called dark current. As shown in Eq. (4.2.8), this dark current is the same thing as the reverse saturation current Is because the photodiode is always reversely biased. Because of the statistical nature of the carrier generation process similar to that has been discussed for the shot noise, the dark current noise can also be treated as a white noise with the power spectral density."

Dark current increases with time and temperature in exactly the same way that a normal photonic signal increases with time and illuminance. It is not noise.

Dark current noise is also similar - there is a random quantum component and a fixed pattern component caused by physical differences between pixel sensitivity.

As Bill said, dark current is an offset. If you know what it is, you can just set the black point to the dark current signal and eliminate it.

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