CODEWITHSUNDEEP
signalsnoiseimagingphotography
Rich95
Rich95

Reputation: 343

Can digital photos contain more than one type of noise?

I am aware of the different noise models usually found in digital photography such as Uniform, Gaussian, Laplace, Lorentz, Poisson, etc.

But do photographs usually contain various types of noises combined or just one?

I've read noise removal software depends on reading the image's histogram to find out the noise distribution and thereby identify which type of noise is in an image but this suggests there is always only one type of noise inherent?

I can't seem to find any information on this. Any info is appreciated.

Upvotes: 1

Views: 48

Answers (1)

NoDataDumpNoContribution
NoDataDumpNoContribution

Reputation: 10869

Yes, digital photons can contain more than one type of noise. They even usually do for two reasons:

Reason 1: Noise during acquisition

  • Readout noise of the camera chip (Gaussian, temperature dependent)
  • Inhomogeneities of the pixels (salt & pepper)
  • Photon shot noise (Poisson, especially for dark objects)

Reason 2: Noise during processing

  • Quantization (converting to RGB24)
  • Compression artifacts (when saving as JPEG)
  • Filter artifacts (by some advanced image processing, smoothing)

All this comes together in general and what you see in most cases (always) is a mixture which means that the noise model actually present in the images is really very difficult to estimate.

Upvotes: 1

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