Nyquist [adjective]: 1, Reference to the Nyquist–Shannon sampling
theorem. 2, The principle [1] that, to most faithfully reproduce an
image at a given digital display's resolution, the 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
--
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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