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At 0.5 cycles/pixel, the Nyquist limit, signal amplitude depends on phase, as visible by the three medium-gray curves where the signal goes 90° out of phase with the pixels.At 0.33 cycles/pixel, 0.66 times the Nyquist limit, amplitude can largely be maintained regardless of phase. Some artifacts are still visible, but minor.
The Kell factor, named after RCA engineer Raymond D. Kell, is a parameter used to limit the bandwidth of a sampled image signal to avoid the appearance of beat frequency patterns when displaying the image in a discrete display device, usually taken to be 0.7. The number was first measured in 1934 by Raymond D. Kell and his associates as 0.64 but has suffered several revisions given that it is based on image perception, hence subjective, and is not independent of the type of display. It was later revised to 0.85 but can go higher than 0.9, when fixed pixel scanning (e.g., CCD or CMOS) and fixed pixel displays (e.g., LCD or plasma) are used, or as low as 0.7 for electron gun scanning.
From a different perspective, the Kell factor defines the effective resolution of a discrete display device since the full resolution cannot be used without viewing experience degradation. The actual sampled resolution will depend on the spot size and intensity distribution. For electron gun scanning systems, the spot usually has a Gaussian intensity distribution. For CCDs, the distribution is somewhat rectangular, and is also affected by the sampling grid and inter-pixel spacing.
Kell factor is sometimes incorrectly stated to exist to account for the effects of interlacing. Interlacing itself does not affect Kell factor, but because interlaced video must be low-pass filtered (i.e., blurred) in the vertical dimension to avoid spatio-temporal aliasing (i.e., flickering effects), the Kell factor of interlaced video is said to be about 70% that of progressive video with the same scan line resolution.
The Kellfactor, named after RCA engineer Raymond D. Kell, is a parameter used to limit the bandwidth of a sampled image signal to avoid the appearance...
Kell antigen system, a group of antigens on the human red blood cell surface Kell dragon, a fictional creature in the Star Wars universe Kellfactor,...
geometries Differing image and pixel aspect ratios Miscellanea such as Kellfactor or interlaced video The exact difference between horizontal and diagonal...
related to Aliasing. Brillouin zone Glossary of video terms Jaggies Kellfactor Sinc filter Sinc function Spectral density Spectral leakage Stroboscopic...
Apple's Retina displays, now ignores font hint information completely. Kellfactor "Georgia & Verdana — Typefaces designed for the screen (finally)". Daniel...
capture High-resolution picture transmission Image scaling Image scanner Kellfactor, which typically limits the number of visible lines to 0.7x of the device...
Font rasterization – Process of converting text from vector to raster Kellfactor PenTile matrix family – Electronic device display Sub-pixel resolution...
by cable. The reception and reproduction of the picture on a TV set. Kellfactor, which limits the vertical resolution in analog television, and both...
have approximately the same horizontal and vertical resolution (see Kellfactor), it should be able to display 228 cycles per line, requiring a bandwidth...
"voxel". Waldo R. Tobler is probably among the first to use the word. Kellfactor Full width at half maximum "Dr". geog.tamu.edu. Archived from the original...
689. PMID 18860341. Canatan D, Acar N, Kiliç B (1999). "Rh Subgroups and Kell Antigens in Patients With Thalassemia and in Donors in Turkey" (PDF). Turkish...
with only 2.5 MHz (typical 3 MHz, as System A made no allowance for the Kellfactor and thus had a "narrow pixel"/"tall line" appearance). Thus even an unusually...
horizontal resolution that is 73% of the vertical resolution, or 51% when the Kellfactor is ignored. A special signal tells the receiver when PALplus is in use...
commonly used standard method of lossy compression for photographic images. Kellfactor. It is a parameter used to determine the effective resolution of a discrete...
The It Factor is an American reality television series which aired for two seasons on the American TV channel Bravo. It followed actors as they attempted...
Martin P, Summers J, Daniels G (November 2007). "Fetal genotyping for the K (Kell) and Rh C, c, and E blood groups on cell-free fetal DNA in maternal plasma"...
Other factors, such as the 39% drop in New York City's unemployment rate between 1992 and 1999, could also explain the decrease reported by Kelling and...
anti-RhE, anti-Rhc, anti-Rhe, anti-RhC, multiantigen combinations, and anti-Kell. Although global prevalence studies of the differential contribution of those...
Pretorius E, Vlok M, Venter C, Bezuidenhout JA, Laubscher GJ, Steenkamp J, Kell DB (August 2021). "Persistent clotting protein pathology in Long COVID/Post-Acute...
eighth films. Gleeson provided the voice of Abbot Cellach in The Secret of Kells, an animated film co-directed by Tomm Moore and Nora Twomey of Cartoon Saloon...
types are associated with inheritance of other diseases; for example, the Kell antigen is sometimes associated with McLeod syndrome. Certain blood types...
Secret History of the LaCroix Label". BonAppetit.com. Retrieved June 8, 2017. Kell, John (March 29, 2016). "Soda Consumption Falls to 30-Year Low In The U.S...
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