Thanks for posting the link. It appears that a number of people are trying
to redefine aliasing to mean what they think it means.
An alias is another name for the same object. This multiple to one
relationship is why the word aliasing was used to describe the effect due to
sampling. A string of samples can be caused by any one of a number of
multiple inputs. There is nothing random about it.
The aliased signals are equally spaced around half the sampling frequency.
If you sample at 10kHz then
4kHz and 6 KHz are indistinguishable, similarly 3 and 7, 2 and 8. The
aliased pattern also repeats every multiple of the sampling frequency; thus
3, 7, 13 and 17 can give the same samples even though they are very
different frequencies.
If grain frequency is just above half the sampling frequency, the camera's
image could look similar to the image with the grain just below the sampling
frequency.
Interference and newtons rings have nothing to do with sampling.
Sampling can result in distortion due to aliasing. A to Ds create
quantization errors which has nothing to do with aliasing.
-jeff
From: "Timpe, Jim" <Jim.Timpe@xxxxxxxxx>
Date: Tue, 23 Sep 2003 11:48:31 -0700
On a more (moiré?) serious note, this article is an interesting read on the
subject.
http://www.photoscientia.co.uk/Grain.htm#whatis
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