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

Started 2 months ago | Discussions thread
sybersitizen Forum Pro • Posts: 14,919
Re: Correction

Currantos wrote:

Mika Y. wrote:

Currantos wrote:

Since most of the noise is in the light you capture, this proposed method won't show you most of the noise of a typical photograph.. It will only show you the small portion of noise that is added by the camera.

Not sure what you mean "noise in the light"?

Noise is only a property of the imaging system. It is not a property of the original object being imaged. There can be variations in value of the object being imaged but that is not noise.

Look at the black sky. Do you see bright noise, the white pixels? These are not noise, they are stars. That is what the astroguys are trying to take pictures of. Now take a look at their pictures. You will see both stars, the original "variations in the object" and the superimposed noise of the photo equipment.

To summarize. ALL of the noise in the photograph is from the camera(lens/sensor/etc). None is from the "light" that comes in.

I hope you have now abandoned the above position.

Unless I'm mistaken, he means shot noise:

Correct, there is shot noise, not sure how that would play into the whole equation, sounds even more complicated now.

Yes indeed, there is shot noise, or photon noise, which is always present in the form of random fluctuations in the photon stream. It's almost inconsequential when light is plentiful, but becomes increasingly important as the quantity of light reaching the sensor is reduced. That is not the camera's fault. Dark current noise and read noise are the camera's fault.

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