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Topic: Chroma subsampling

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	mir DMG: Chroma Subsampling
		Chroma is sampled at half the horizontal frequency as luma, but the vertical frequency is the same.
		Chroma is sampled at half the horizontal frequency as luma, and also at half the vertical frequency.
		Chroma subsampling modes are defined by a pair of ratios and a pair of offsets.
	www.mir.com /DMG/chroma.html (600 words)

	Chroma subsampling (Site not responding. Last check: )
		In image processing, chroma subsampling is the use of lower resolution for the colour (chroma) information in an image than for the brightness (intensity or luma) information.
		Because the human eye is less sensitive to colour than intensity, the chroma components of an image need not be as well defined as the luma component, so many video systems sample the colour at a lower definition than the brightness.
		Cartel (Punk) - Chroma [9/20] * - $12.11
	www.serebella.com /encyclopedia/article-Chroma_subsampling.html (235 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		Chroma subsampling is the practice of implementing more resolution for the (quantity representative of) luminance than the (quantity representative of) color.
		Chroma subsampling deviates from color science in that the luma and chroma components are formed as a weighted sum of gamma-corrected">gamma-corrected (tristimulus) R'G'B' components instead of linear (tristimulus) RGB components.
		In some professional circles, the 4:1:1 chroma subsampling of the DV format was initially not considered broadcast quality and only acceptable for low-end and consumer applications [1] [2].
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Chroma_subsampling (1571 words)

	Chroma subsampling in JPG compression
		One tradeoff that is commonly employed is chroma subsampling.
		Chroma subsampling is a method that stores color information at lower resolution than intensity information.
		Chroma subsampling may be a reasonable compression strategy for high resolution images, but for color web images, one is better served by turning off chroma subsampling and compressing more aggressively to achieve the same file size.
	www.wfu.edu /~matthews/misc/jpg_vs_gif/JpgCompTest/JpgChromaSub.html (982 words)

	ImpulseAdventure - JPEG Chroma Subsampling
		Chroma subsampling is the process whereby the color information in the image is sampled at a lower resolution than the original.
		In the case of 2x1 (4:2:2) chroma subsampling -- only one for every 2 pixels is used in the horizontal direction, but every pixel in the vertical direction is retained.
		The fact that JPEG chroma subsampling relies on the limitations of the human eye means that it is not a particularly good mechanism for compressing images used by other "sensors" (such as in the medical field, etc.), where the chrominance may be equally as important as the luminance.
	www.impulseadventure.com /photo/chroma-subsampling.html (2630 words)

	Chroma subsampling
		In image processing, chroma subsampling is the use of lower resolution for the colour (chroma) information in an image than for the brightness (intensity or luma) information.
		Because the human eye is less sensitive to colour than intensity, the chroma components of an image need not be as well defined as the luma component, so many video systems sample the colour at a lower definition than the brightness.
		The three terms of the ratio are: the number of luma pixels in a complete sample area, the number of chroma pixels in odd lines, and the number of chroma pixels in even lines:
	www.ebroadcast.com.au /lookup/encyclopedia/ch/Chroma_subsampling.html (131 words)

	Online Glossary of CD / DVD Related Terms - ProAction Media
		Chroma is sampled on every line, but only for every four luma pixels (i.e., 1 pixel in a 1 x 4 grid).
		This amounts to a subsampling of chroma by a factor of two compared to luma (and by a factor of four for a single Cb or Cr component).
		Cb and Cr are sampled on every other line, in between the scan lines, with one set of chroma samples for each two luma samples on a line.
	www.proactionmedia.com /cd_dvd_glossary.htm (13854 words)

	Videosmith by Steven Trent Smith- The Digital Journalist
		Chroma Subsampling: This describes the amount of color data recorded.
		The subsampling rates make use of human physiology -- our eyes are less sensitive to color than they are to brightness.
		While the Holy Grail of subsampling is 4:4:4, none of the major formats employ it (except HDCAM SR).
	dirckhalstead.org /issue0604/smith.html (618 words)

	Apparatus for subsampling chrominance - Patent 5477345
		Chroma subsampling may therefore be usefully employed in a number of color scanning situations due to a number of factors.
		The filtered video signal is subsampled and applied to a peaking filter which amplifies the band of frequencies containing the aliasing components relative to lower frequency bands to improve thee appearance of detailed portions of the reproduced image.
		The chroma subsampling processor of the present invention provides for much needed data reduction for color image chrominance subsampling by employing a means that subsamples the scanned image at the point of the sensor array, rather than relying on processing and storage hardware and software to carry out the subsampling process.
	www.freepatentsonline.com /5477345.html (7976 words)

	Reference Encyclopedia - DV (Site not responding. Last check: )
		Chroma Subsampling: Since human vision has greater acuity for luminance than color, performance can be optimized by devoting greater bandwidth to luminance than color.
		The chroma subsampling is 4:1:1 for NTSC, 4:1:1 for DVCPRO PAL, and 4:2:0 for other PAL.
		Low chroma resolution is a reason why DV is sometimes avoided in applications where chroma-key will be used.
	www.referenceencyclopedia.com /?title=DV (3311 words)

	Chroma subsampling (Site not responding. Last check: )
		In digital image processing, chroma subsampling is the use of lower resolution for the colour (''chroma'') information in an image than for the brightness (''intensity'' or luma) information.
		Because the human eye is less sensitive to colour than intensity, the chroma components of an image need not be as well defined as the luma component, so many video systems sample the colour difference channels at a lower definition (i.e., sample frequency) than the brightness.
		In 4:1:1 chroma subsampling, the horizontal color resolution is quartered.
	chroma-subsampling.borgfind.com (754 words)

	Busted Skull » 2005 » January (Site not responding. Last check: )
		Many (some?) people are familiar with 4:2:2 and 4:1:1 subsampling, where the frequency of chroma samples is 50% and 25% respectively of that of luma.
		In 4:2:0 subsampling, however, chroma is subsampled by 50% both horizontally and vertically.
		In order to avoid this problem, we need to subsample the video as interlaced video, but this results in significant loss in vertical chroma resolution in the progressive frames, since our chroma samples are now out of order.
	www.bustedskull.com /index.php?m=200501 (429 words)

	Chroma
		For the band of the same name, see Chroma Key.'' A chroma key is the removal of a color (or small color range) from one image to reveal another "behind" it.
		When the phase of the chroma signal corresponds to the preprogrammed state or states associated with the background color(s) behind the principal subject, the signal from the alternate background is inserted in the composite signal and presented at the output.
		When the phase of the chroma signal deviates from that associated with the background color(s) behind the principal subject, video associated with the principal subject is presented at the output.
	www.breadlike.com /pages7/18/chroma.html (1008 words)

	Chroma subsampling in JPG compression
		The subsampling process demands two conversions of the image: from the original red/green/blue representation to an intensity+color representation, and then back again when the image is displayed.
		One of the most important algorithmic differences is the the choice of whether or not to use chroma subsampling.
		One should note that turning off chroma subsampling may not always be the wisest choice for compromising between file size and image quality.
	users.wfu.edu /matthews/misc/jpg_vs_gif/JpgCompTest/JpgChromaSub.html (982 words)

	DV vs. Betacam SP
		There are two chroma signals (Cr and Cb), so the resulting digital bitstream is composed of equal quantities of luma and chroma data.
		Assuming one accepts the preceding argument regarding the equivalent chroma bandwidth of 4:1:1 DV and Betacam SP, the issue of spatial uncertainty of chroma-keyed graphics remains.
		Chroma green paint, paper, and cloth is as readily available from video accessory vendors as is chroma blue.
	www.dvcentral.org /DV-Beta.html (3827 words)

	FilmStudentBlog.com » Blog Archive » Chroma Subsampling Rates Explained
		Currently, weak chroma subsampling rates is one of the biggest hindrances of digital video; a lack of color information is on big reason why digital video looks dull.
		Granted, a chroma subsampling rate would be a silly decision to pick a certain camera package.
		Chroma subsampling rates are like a girlfriend/boyfriend: even if you know plenty of information regarding the topic, you shouldn’t disclose every last little detail.
	filmstudentblog.com /chroma-subsampling-rates-explained (786 words)

	DV - Glasglidius (Site not responding. Last check: )
		Chroma Subsampling: Since human vision has greater acuity for luminance than color, performance can be optimized by devoting greater bandwidth to luminance than color.
		The chroma subsampling is 4:1:1 for NTSC, 4:1:1 for DVCPRO PAL, and 4:2:0 for other PAL.
		Low chroma resolution is a reason why DV is sometimes avoided in applications where chroma-key will be used.
	www.glasglow.com /e/?title=DV (3121 words)

	Improved Color Subsampling (Site not responding. Last check: )
		A common source of objectionable artifacts from chroma subsampling is typically found on titles encoded with mainstream DV codecs (which employs 4:1:1 color subsampling).
		In Y'CbCr encoding (used in many image encoding schemes), chroma is used to approximate color (chrominance to be exact) and luma is used to approximate luminance.
		Luma and chroma differ from the luminance and chrominance of color science in how the values are formed.
	www.glennchan.info /articles/technical/chromata/chromata.html (1715 words)

	Talk:OggYUV - XiphWiki
		We need to know two things, what the size/shape of chroma pixels are, and if they are packed, what order they are provided in the bitstream.
		The order must match the shape it's based on, ie, 4:4:4 should be in "0:0" order, any other value (which is illegal) should not be supported by any software if encountered and should never be generated.
		Dash (-) indicates a luma sample without a chroma sample, and # indicates a luma and chroma sample, I'm not sure if this is the same as used above or not..
	wiki.xiph.org /index.php?title=Talk:OggYUV&redirect=no (626 words)

	Chroma subsampling Information - Chroma subsampling
		For quality comparison, only the ratio between those values is important, so 4:4:4 could easily be called 1:1:1; however, traditionally the value for brightness is always 4, with the rest of the values scaled accordingly.
		In these cases, the fourth Chroma subsampling number means the sampling frequency ratio of a key channel.In virtually all cases, that number will be 4, since high quality is very desirable in keying applications.
		CCIR 601 / Serial Digital Interface / D1 In 4:1:1 chroma subsampling, the horizontal color resolution is quartered.
	www.inanot.com /Ina-Electronics_Topics_C_-_Cm-/Chroma_subsampling.html (774 words)

	Chroma Subsampling - definition erklärung bedeutung glossar zu Chroma Subsampling (Site not responding. Last check: )
		Chroma Subsampling - definition erklärung bedeutung glossar zu Chroma Subsampling
		Chroma Subsampling meint eine zu niedrigere Abtastrate für Farbinformationen.
		In vielen Fällen genügt eine geringere Auflösung für die Farbinformation (Chroma) als für die Helligkeit (Luma), da Helligkeitsunterschiede vom menschlichem Auge stärker wahrgenommen werden als Farbunterschiede.
	www.adlexikon.de /Chroma_Subsampling.shtml (241 words)

	DXVA2_VideoChromaSubSampling Enumeration
		Chroma should be reconstructed as if the underlying video was progressive content, rather than skipping fields or applying chroma filtering to minimize artifacts from reconstructing 4:2:0 interlaced chroma.
		Chroma samples are aligned horizontally with the luma samples, but are not aligned vertically.
		Chroma samples are aligned vertically and horizontally with the luma samples.
	msdn.microsoft.com /library/en-us/medfound/html/0f9d63fd-46fa-498c-8703-1beeaf09ce86.asp?frame=true (383 words)

	Chroma subsampling Information
		Chroma subsampling is the use of implementing more resolution for the (quantity representative of) luminance information than the (quantity representative of) color information.
		Chroma sumsampling deviates from color science in that the luma and chroma components are formed as a weighted sum of gamma-corrected (tristimulus) R'G'B' components instead of linear (tristimulus) RGB components.
		Also note that the diagram does not show chroma filtering or from which pixels the chroma values are sampled from.
	www.bookrags.com /wiki/Chroma_subsampling (1195 words)

	DVD Demystified Glossary
		Chroma is sampled on every line, but only for every four luma pixels (i.e., 1 pixel in a 1 x 4 grid).
		This amounts to a subsampling of chroma by a factor of two compared to luma (and by a factor of four for a single Cb or Cr component).
		Cb and Cr are sampled on every other line, in between the scan lines, with one set of chroma samples for each two luma samples on a line.
	www.dvddemystified.com /glossary.html (13787 words)

	Chroma - Qwika
		Chroma ARP Chroma or Rhodes Chroma it is one sintetizzatore musical polifonico and...
		ARP Chroma This instrument, eventually released by Fender as the Rhodes Chroma, was one of the early microprocessor-based...
		Chroma key Chroma key is with Colour television a procedure...
	www.qwika.com /find/Chroma (514 words)

	PhotoYCC Color Encoding and Compression Schemes (Site not responding. Last check: )
		In each image component except 4Base, the luma channel is accompanied by two chroma channels that have been subsampled by a factor of 2 in both the horizontal and vertical directions.
		Thus, only one pixel from each of the chroma channels is required for every four pixels from the luma channel.
		Chroma subsampling reduces the size of the 2k x 3k or the 4k x 6k raw image to 9 or 36 megabytes respectively.
	www.kodak.com /global/en/professional/products/storage/pcd/techInfo/pcd-045.jhtml (2222 words)

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