On 10/01/2020 01:20 AM, Eduardo Alarcón wrote:
Nyquist is a noun, not an adjective, for Harry Nyquist. ...
Hi Eduardo, Thanks.
Well, technically, a noun used as an adjective: "Nyquist sampling", makes it an adjective, but no
matter.
What if I narrow the scope to solely the sampling theory? thusly:
Nyquist sampling: The principle [1] that, to most faithfully reproduce
an image at a given digital display's resolution, samples must be
made at or above twice the display's resolution, both horizontally &
vertically [2].
[1] The Nyquist principle applies to film sampling and to digital
cameras, but, provided that resolution is unchanged, not to
transcoding (because the transcoder inputs are already digital).
As proved by the improved appearance of SD media made from 2K
samples, SD mastering prior to the advent of 2K sampling (e.g.
DVDs mastered before the advent of HD) generally ignored the
Nyquist principle and were undersampled. HDs sampled at 2K and
UHDs sampled at 4K are likewise undersampled.
[2] As a convenience, the Nyquist threshold is currently (in 2020)
specified solely by horizontal sample count rounded up to whole
kilo-samples (2K, 4K, 8K).
display Nyquist threshold
UHD 16:9-2160: 3840 x 2160 8K
4:3-2160: 2880 x 2160 8K
HD 16:9-1080: 1920 x 1080 4K
4:3-1080: 1440 x 1080 4K
SD 16:9-576: 1024 x 576 4K
4:3-576: 768 x 576 2K
16:9-480: 853 x 480 2K
4:3-480: 640 x 480 2K
... The Nyquist–Shannon
sampling theorem is applicable to analog to digital conversion of signals
(continuous to discrete), images are a type of signal.
Well, I thought that was what I wrote. What doesn't work for you?
The reason I wrote "both horizontally & vertically" was to resolve that, unlike sampling a
1-dimensional (serial) signal, 2-dimensional sampling (e.g. from film) or within a camera, requires
the Nyquist principle be applied in both dimensions. But perhaps that's not what you find lacking.
Could you suggest different wording maybe?
--
What if you woke up and found yourself in a police state?
African-Americans wake up in a police state every day.
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