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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. It is used when an analog component video or YUV signal is digitally sampled. This article needs to be cleaned up to conform to a higher standard of quality. ...
The word resolution has several meanings, depending on context. ...
Color is an important part of the visual arts. ...
three RCA cables form the component video Component video is a type of analog video information that is transmitted or stored as two or more separate signals (as opposed to composite video, such as NTSC or PAL, which is a single signal). ...
Example of U-V color plane, Y value = 0. ...
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. This reduces the overall bandwidth of the video signal without much apparent loss of picture quality. The missing values will be interpolated or repeated from the preceding sample for that channel. Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ...
Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ...
A sample refers to a value or set of values at a point in time and/or space. ...
Jump to: navigation, search Bandwidth is a measure of frequency range. ...
Signaling, or signal, may mean: Look up signal on Wiktionary, the free dictionary. ...
The subsampling in a video system is usually expressed as a three part ratio. The three terms of the ratio are: the number of brightness ("luminance" "luma" or Y) samples, followed by the number of samples of the two colour ("chroma") components: U/Cb then V/Cr, for each complete sample area. 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. Example of U-V color plane, Y value = 0. ...
Sample can refer to any of the following. ...
Example of U-V color plane, Y value = 0. ...
Example of U-V color plane, Y value = 0. ...
 Demonstrate common chroma subsampling ratios with big-pixel diagrams. ...
Sometimes, four part relations are written, like 4:2:2:4. In these cases, the fourth 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. In graphics, keying is an informal term for compositing two full frame images together, by discriminating the visual information into values of color and light. ...
NOTE: The mapping examples given are only theoretical and for illustration. The bitstreams of real-life implementations will probably differ.
4:4:4
Each of the three channels has the same sample rate, so each single pixel in the resulting image gets three full words (usually 8 or 10 bits long) of information, resulting in 3 bytes per pixel for 8-bit quantization when not using compression. Generally, quantization is the state of being constrained to a set of discrete values, rather than varying continuously. ...
Mapping:
The bitstream
Y0 U0 V0 Y1 U1 V1 Y2 U2 V2 Y3 U3 V3 will map to the following four pixels: [Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] This is the best color sampling ratio (it yields a perfect representation of each pixel's color), and is used as an intermediate format in high-end film scanners and cinematic postproduction. Note that 4:4:4 may (and often indeed does, as in some modes of HDCAM SR) also mean that the three values are all color values in the RGB color space, which must always be sampled at the same frequency. Betacam and VHS size comparison Betacam SP L, Betacam SP S, VHS Betacam is a family of half-inch professional videotape formats developed by Sony from 1982 onwards. ...
The RGB color model utilizes the additive model in which red, green, and blue light are combined in various ways to create other colors. ...
4:2:2 Each of the two color-difference channels has half the sample rate of the brightness channel, so horizontal color resolution is only half that of 4:4:4. For uncompressed video and 8-bit quantization, each macropixel of two neighbouring pixels uses 4 bytes of memory.
Mapping:
The bitstream
Y0 U0 Y1 V1 Y2 U2 Y3 V3 will map to the following four pixels: [Y0 U0 V1] [Y1 U0 V1] [Y2 U2 V3] [Y3 U2 V3] This is still a very good quality, and most higher-end digital video formats use this ratio: Betacam and VHS size comparison Betacam SP L (top), Betacam SP S (left), VHS (right) Betacam is a family of half-inch professional videotape formats developed by Sony from 1982 onwards. ...
A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
CCIR 601 is the old name of a standard published by the CCIR (now ITU-R) for encoding interlaced analogue video signals in digital form. ...
Jump to: navigation, search Serial Digital Interface (SDI), standardized in ITU-R 656 and SMPTE-259M, is a digitized video format used for broadcast grade video. ...
Sonys D1 format was the first major professional digital video format, introduced in 1987. ...
4:1:1 In 4:1:1 chroma subsampling, the horizontal color resolution is quartered. This is still acceptable for lower-end and consumer applications. Uncompressed video in this format with 8-bit quantization uses 6 bytes for every macropixel (4 pixels in a row).
Mapping:
The bitstream
Y0 U0 Y1 Y2 V2 Y3 will map to the following four pixels: [Y0 U0 V2] [Y1 U0 V2] [Y2 U0 V2] [Y3 U0 V2] Formats that use 4:1:1 chroma subsampling include: A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
4:2:0 4:2:0 does not mean that there is no V or Cr information stored at all, it means that in each line, only one color difference channel is stored with half the horizontal resolution. The channel which is stored flips each line, so the ratio is 4:2:0 for one line, 4:0:2 in the next, then 4:2:0 again, and so on. This leads to half the horizontal as well as half the vertical resolution, giving a quarter of the color resolution overall. The PAL and SECAM color systems are especially well-suited to this kind of data reduction. Uncompressed video in this format with 8-bit quantization uses 6 bytes for every macropixel (2×2 pixels). For other meanings of PAL see PAL (disambiguation). ...
SÉCAM (Séquentiel couleur à mémoire, French for sequential colour with memory) is an analog color television system first used in France. ...
Mapping:
The bitstream
Yo0 Uo0 Yo1 Yo2 Uo2 Yo3
Ye0 Ve0 Ye1 Ye2 Ve2 Ye3 will map to the following two lines of four pixels each: [Yo0 Uo0 Ve0] [Yo1 Uo0 Ve0] [Yo2 Uo2 Ve2] [Yo3 Uo2 Ve2]
[Ye0 Uo0 Ve0] [Ye1 Uo0 Ve0] [Ye2 Uo2 Ve2] [Ye3 Uo2 Ve2] The quality of this method is very close to 4:1:1, and it is used in the following formats: - DVD and other Main Profile MPEG-2 implementations
- PAL DV and DVCAM
- most common JPEG and MJPEG implementations
Jump to: navigation, search DVD is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. ...
Jump to: navigation, search MPEG-2 (1994) is the designation for a group of coding standards for digital audio and video, agreed upon by MPEG (Moving Pictures Experts Group), and published as the ISO/IEC 13818 international standard. ...
For other meanings of PAL see PAL (disambiguation). ...
A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
A MiniDV tape Digital Video (DV) is a video format launched in 1996, and, in its smaller tape form factor MiniDV, has since become one of the standards for consumer and semiprofessional video production. ...
A photo of a flower compressed with successively higher compression ratios from left to right. ...
Motion JPEG (M-JPEG) is a video codec where each video field is separately compressed into a JPEG image. ...
4:1:0 This ratio is possible (indeed, some codecs do support it), but not widely used, since its color fidelity is even below that of VHS. It means half the vertical and quarter the horizontal color resolutions, with only one eighth of the bandwidth of the maximum color resolutions used. Uncompressed video in this format with 8-bit quantization uses 10 bytes for every macropixel (4 x 2 pixels). Codec is a portmanteau of coder/decoder, which describes a device or program capable of performing transformations on a data stream or signal. ...
Jump to: navigation, search Top view VHS cassette with US Quarter for scale Bottom view of VHS cassette with magnetic tape exposed The Video Home System, first released in 1976, better known by its acronym VHS, is a recording and playing standard for video cassette recorders (VCRs), developed by JVC...
Mapping:
The bitstream
Yo0 Uo0 Yo1 Yo2 Yo3
Ye0 Ve0 Ye1 Ye2 Ye3 will map to the following two lines of four pixels each: [Yo0 Uo0 Ve0] [Yo1 Uo0 Ve0] [Yo2 Uo0 Ve0] [Yo3 Uo0 Ve0]
[Ye0 Uo0 Ve0] [Ye1 Uo0 Ve0] [Ye2 Uo0 Ve0] [Ye3 Uo0 Ve0] | 
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