Getting down to the nitty-gritty about noise and it's effect on IQ Locked

Started Apr 15, 2010 | Discussions thread
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Joofa Senior Member • Posts: 2,655
Re: Getting down to the nitty-gritty about noise and it's effect on IQ

Crocodile Gena wrote:

I hope we can all agree that a greater amplitude of noise is undesireable, whereas a greater frequency of noise is desireable. The problem comes from comparing the amplitudes of noise at different frequencies. If one image has a greater amplitude of noise at a higher frequency than another image which has a lower amplitude of noise at a lower frequency (the case for the images above), does that make it "more noisy"?

Comparing noise amplitude at different frequencies is not well-defined. What you need to compare here is the noise power at different frequencies. Two different things. And, then you have to have a methodology/assumption of going from the non-stationarity of noise in natural images to stationary noise if you are going to talk more meaningful things about power spectrum.

In other words, using scalar descriptors ("more" / "less") to describe noise in scalar (single-valued) terms makes sense only if the maximum frequencies are the same. But if we are comparing vector quantities (amplitude / frequency), such a simplistic comparison does not accurately relate to the IQ of the final image.

There is no problem with the scalar/vector issue here. As the scalar quantity in this case can be obtained from the integral/summation of the vector quantity along the frequency variable.


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Dj Joofa

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