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Ultra High Definition Video

Ultra High Definition Video

Super Hi-Vision, also known as Ultra High Definition Video or UHDV is a digital video format, currently proposed by NHK of Japan.
- Resolution: 7,680 × 4,320 pixels.
- Frame rate: 60 frame/s.
- 22.2-channel audio
- 9 - above ear level
- 10 - ear level
- 3 - below ear level
- 2 - low frequency effects The new format is four times as wide and four times as high as existing HDTV, which has a maximum resolution of 1920 × 1080 pixels. Because this format is highly experimental, NHK researchers had to build their own prototype from scratch. In the system demonstrated in September 2003 they used an array of 16 HDTV recorders to capture the 18-minute-long test footage. The camera itself was built with four 2.5 inch (64 mm) CCDs. 18 minutes of UHDV consumes 3.5 terabytes of data. Preliminary response of the UHDV was somewhat negative. This was not because of the lack of the promised technology, but more in the fact that it was too good. Some viewers got motion sickness when viewing the video image. This was due to the fact that the image was so close to reality. In November 2005 NHK demonstrated a live relay of Super Hi-Vision (UHDV) program over a distance of 260 km by a fiberoptic network. 24 gigabit speed was achieved using DWDM (dense wavelength division multiplex) method with a total of 16 different wavelength signals.

External links

- [http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=173402762 Super Hi-Vision Demo]
- [http://whatis.techtarget.com/definition/0,,sid9_gci932318,00.html UHDV at Whatis.com]
- [http://www.cdfreaks.com/news2.php?ID=8067 Ultra high resolution television (UHDV) prototype]
- [http://www.nytimes.com/2004/06/03/technology/circuits/03next.html?ex=1401595200&en=935183cee9a4bd49&ei=5007&partner=USERLAND The New York Times: Just Like High-Definition TV, but With Higher Definition]
- [http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=173402762 Japan demonstrates next-gen TV broadcast] Category:Video and movie technology

Video

Video is the technology of capturing, recording, processing, transmitting, and reconstructing moving pictures, typically using celluloid film, electronic signals, or digital media.

Description

moving picture The term video (from the Latin for "I see") commonly refers to several storage formats for moving pictures: digital video formats, including DVD, QuickTime, and MPEG-4; and analog videotapes, including VHS and Betamax. Video can be recorded and transmitted in various physical media: in celluloid film when recorded by mechanical cameras, in PAL or NTSC electric signals when recorded by video cameras, or in MPEG-4 or DV digital media when recorded by digital cameras. Quality of video essentially depends on the capturing method and storage used. Digital television (DTV) is a relatively recent format with higher quality than earlier television formats and has become a standard for television video. (See List of digital television deployments by country.) 3D-video, digital video in three dimensions, premiered at the end of 20th century. Six or eight cameras with realtime depth measurement are typically used to capture 3D-video streams. The format of 3D-video is fixed in MPEG-4 Part 16 Animation Framework eXtension (AFX). In the UK, the term video is often used informally to refer to both video recorders and video cassettes; the meaning is normally clear from the context.

Characteristics of video streams

Number of frames per second

Frame rate, the number of still pictures per unit of time of video, ranges from six or eight frames per second (fps) for old mechanical cameras to 120 or more frames per second for new professional cameras. PAL (Europe) and SECAM (France) standards specify 25 fps, while NTSC (North America) specifies 30 fps. To achieve the illusion of a moving image, the minimum frame rate is about ten frames per second.

Interlacing

Video can be interlaced or progressive. Interlacing was invented as a way to achieve good visual quality within the limitations of a narrow bandwidth. The horizontal scan lines of each interlaced frame are numbered consecutively and partitioned into two fields: the odd field consisting of the odd-numbered lines and the even field consisting of the even-numbered lines. NTSC, PAL and SECAM are interlaced formats. Abbreviated video resolution specifications often include an i to indicate interlacing. For example, PAL video format is often specified as 576i50, where 576 indicates the horizontal resolution, i indicates interlacing, and 50 indicates 50 (single-field) frames per second. In progressive scan systems, each frame includes all of the scan lines. The result is a much higher perceived resolution. A procedure known as deinterlacing can be used for converting an interlaced stream, such as analog, DVD, or satellite, to be processed by progressive scan devices, such as TFT TV-sets, projectors, and plasma panels. Deinterlacing inevitably decreases video quality.

Video resolution

video quality The size of a video image is measured in pixels for digital video or horizontal scan lines for analog video. Standard-definition television (SDTV) is specified as 640×480i60 for NTSC and 720×576i50 for PAL or SÉCAM resolution. New high-definition televisions (HDTV) are capable of resolutions up to 1920×1080p60, i.e. 1920 pixels per scan line by 1080 scan lines, progressive, at 60 frames per second. Video resolution for 3D-video is measured in voxels (volume picture element, representing a value in three dimensional space). For example 512×512×512 voxels resolution, now used for simple 3D-video, can be displayed even on some PDAs.

Aspect ratio

PDA (green) aspect ratios.]] Aspect ratio describes the dimensions of video screens and video picture elements. The screen aspect ratio of a traditional television screen is 4:3, or 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack (also known as "Academy standard") is around 1.37:1. Pixels on computer monitors are usually square, but pixels used in digital video have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video standard, and the corresponding anamorphic widescreen formats.

Color space and Bits per pixel

CCIR 601 Color model name describes the video color representation. YIQ is used in NTSC television. It corresponds closely to the YUV scheme used in PAL television and the YDbDr scheme used by SÉCAM television. The number of distinct colours that can be represented by a pixel depends on the number of bits per pixel (bpp). A common way to reduce the number of bits per pixel in digital video is by chroma subsampling (e.g. 4:4:4, 4:2:2, 4:2:0).

Video quality

Video quality can be measured with formal metrics like PSNR or with subjective video quality using expert observation. The subjective video quality of a video processing system may be evaluated as follows:
- Choose the video sequences (the SRC) to use for testing.
- Choose the settings of the system to evaluate (the HRC).
- Choose a test method for how to present video sequences to experts and to collect their ratings.
- Invite a sufficient number of experts, preferably not fewer than 15.
- Carry out testing.
- Calculate the average marks for each HRC based on the experts' ratings. Many subjective video quality methods are described in the ITU-T recommendation BT.500. One of the standardized method is the Double Stimulus Impairment Scale (DSIS). In DSIS, each expert views an unimpaired reference video followed by an impaired version of the same video. The expert then rates the impaired video using a scale ranging from "impairments are imperceptible" to "impairments are very annoying".

Video compression method (digital only)

A wide variety of methods are used to compress video streams. Video data contains spatial and temporal redundancy, making uncompressed video streams extremely inefficient. Broadly speaking, spatial redundancy is reduced by registering differences between parts of a single frame; this task is known as intraframe compression and is closely related to image compression. Likewise, temporal redundancy can be reduced by registering differences between frames; this task is known as interframe compression, including motion compensation and other techniques. The most common modern standards are MPEG-2, used for DVD and satellite television, and MPEG-4, used for home video.

Bit rate (digital only)

Bit rate is a measure of the rate of information content in a video stream. It is quantified using the bit per second (bit/s) unit or Megabits per second (Mbit/s). A higher bit rate allows better video quality. For example, VHS, with a bit rate of about 1 Mbit/s, is lower quality than DVD, with a bit rate of about 5 Mbit/s. HDTV has a still higher quality, with a bit rate of 10 Mbit/s. Variable bit rate (VBR) is a strategy to maximize the visual video quality and minimize the bit rate. On fast motion scenes, a variable bit rate uses more bits than it does on slow motion scenes of similar duration yet achieves a consistent visual quality. For real-time and non-buffered video streaming when the available bandwidth is fixed, e.g. in videoconferencing delivered on channels of fixed bandwidth, a constant bit rate (CBR) must be used.

Stereoscopic

Stereoscopic video requires either two channels — a right channel for the right eye and a left channel for the left eye or two overlayed color coded layers. This left and right layer technique is occasionally used for network broadcast, or recent "anaglyph" releases of 3D movies on DVD. Simple Red/Cyan plastic glasses provide the means to view the images discreetly to form a stereoscopic view of the content. New HD DVD and HD Blu-ray disks will greatly improve the 3D effect, in color coded stereo programs. See articles Stereoscopy and 3-D film.

Video formats

NHK

NHK (日本放送協会, Nihon Hōsō Kyōkai), or the Japan Broadcasting Corporation, is Japan's public broadcaster. Radio Tokyo and Radio Japan are informal English names, referring to NHK's original role as a radio broadcaster. Today it operates two terrestrial television services (NHK General TV and NHK Educational TV), three satellite services (NHK BS-1, NHK BS-2, and NHK Hi-Vision – High-definition TV), and three radio networks (NHK Radio 1, NHK Radio 2, and NHK FM). For audiences overseas it also broadcasts NHK World TV, NHK World Premium, and NHK World Radio.

History

NHK was founded in 1926, modelled on the BBC radio company. A second radio network was started in 1931 and a shortwave service broadcasting to listeners overseas began in 1935. In November 1941, The Imperial Japanese Army nationalized all public news agencies and coordinated their efforts through the Information Liaison Confidential Committee, which included representatives from the Army, the Navy, the Foreign Ministry, the Government Information Office, the Cabinet Information Bureau, the Home Ministry, the Ministry of Greater East Asia, the Transportation Ministry, the Domei News Agency and the NHK. Thereafter, all published and broadcast news reports became official announcements of the Imperial Army General Headquarters in Tokyo for the duration of World War II. NHK started television broadcasts in 1953. It aired its first colour television broadcast in 1960. Although the network first introduced commercial broadcasts to Japan, nowadays NHK is paid for by viewer fees. Residents of Japan who own a TV are obliged to pay a fee of about USD 12 per month under the "Hōsō Hō" (Broadcasting Act). However, the act does not stipulate any punishment for failure of payment. NHK World TV started broadcasts in 1995. The entire NHK network moved to digital broadcasting in 2000.

TV Programming

2000 NHK General TV broadcasts a variety of programming. The following are noteworthy:
- News. Local, national, and world news reports.
- Weather. Weather in detail, nationwide, and international for travellers.
- Sports. NHK broadcasts the six annual Grand Sumo tournaments, high-school baseball championships from Koshien Stadium, Olympic Games, and a range of other sports.
- News analysis. The network carries in-depth reports on current topics, political debate, and similar programming.
- Music. The annual Kōhaku Uta Gassen on New Year's Eve is the highlight. The weekly schedule includes an amateur hour, and prime-time shows for all ages.
- Drama. A sentimental morning show, a weekly jidaigeki and a year-long show, the Taiga drama, spearhead the network's fiction offerings.
- Documentaries. NHK has become known for its documentary series, first popularized by the miniseries Legacy for the Future.
- Other. Cooking, comedy, anime, exercise, etc. See also: Japanese television programs, International broadcasting in Japan, Japanese media

External links

- [http://www.nhk.or.jp NHK Japanese website]
- [http://www.nhk.or.jp/english/ NHK English website] Category:Commercial-free television networks Category:Media of Japan Category:Japanese radio Category:Japanese television Category:Publicly-funded broadcasters Category:Television networks in Japan ko:NHK ms:NHK ja:日本放送協会

Charge-coupled device

A charge-coupled device (CCD) is a sensor for recording images, consisting of an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to one or other of its neighbours. CCDs are used in digital photography and astronomy (particularly in photometry, optical and UV spectroscopy and high speed techniques such as lucky imaging).

Applications

CCDs containing grids of pixels are used in digital cameras, optical scanners and video cameras as light-sensing devices. They commonly respond to 70% of the incident light (meaning a quantum efficiency of about 70%,) making them more efficient than photographic film, which captures only about 2% of the incident light. As a result CCDs were rapidly adopted by astronomers. quantum efficiency] An image is projected by a lens on the capacitor array, causing each capacitor to accumulate an electric charge proportional to the light intensity at that location. A one-dimensional array, used in line-scan cameras, captures a single slice of the image, while a two-dimensional array, used in video and still cameras, captures the whole image or a rectangular portion of it. Once the array has been exposed to the image, a control circuit causes each capacitor to transfer its contents to its neighbour. The last capacitor in the array dumps its charge into an amplifier that converts the charge into a voltage. By repeating this process, the control circuit converts the entire contents of the array to a varying voltage, which it samples, digitizes and stores in memory. Stored images can be transferred to a printer, storage device or video display. CCDs are also widely used as sensors for astronomical telescopes, and night vision devices. An interesting astronomical application is to use a CCD to make a fixed telescope behave like a tracking telescope and follow the motion of the sky. The charges in the CCD are transferred and read in a direction parallel to the motion of the sky, and at the same speed. In this way, the telescope can image a larger region of the sky than its normal field of view. CCDs are typically sensitive to infrared light, which allows infrared photography, night-vision devices, and zero lux (or near zero lux) video-recording/photography. Because of their sensitivity to infrared, CCDs used in astronomy are usually cooled to liquid nitrogen temperatures, because infrared black body radiation is emitted from room-temperature sources. One other consequence of their sensitivity to infrared is that infrared from remote controls will often appear on CCD-based digital cameras or camcorders, if they don't have infrared filters. Cooling also reduces the array's dark current, improving the sensitivity of the CCD to low light intensities, even for ultraviolet and visible wavelengths. Thermal noise, dark current, and cosmic rays may alter the pixels in the CCD array. To counter such effects, astronomers take an average of several exposures with the CCD shutter closed. This average is necessary to compensate for random noise. Once developed, the "dark frame" image is then subtracted from the original image to remove the thermal noise effects. CCD cameras used in astrophotography often require very sturdy mounts to cope with vibrations and breezes, along with the tremendous weight that most imaging platforms inherently cause. To take long CCD exposures of galaxies and nebulae, many astronomers use a technique known as auto-guiding. Most autoguiders use off-axis CCD chips to monitor any deviation from the imaging, however, some, like the [http://www.sbig.com/ SBIG AO-7], have the autoguider CCD and the imaging CCD in the same camera. Auto-guiders use a second CCD chip which can rapidly detect period errors in tracking and command the mount's motors to correct for them.

Color cameras

Digital color cameras generally use a Bayer mask over the CCD. Each square of four pixels has one filtered red, one blue, and two green (the human eye is more sensitive to green than either red or blue). The result of this is that luminance information is collected at every pixel, but the color resolution is lower than the luminance resolution. Better color separation can be reached by three-CCD devices (3CCD) and a dichroic beam splitter prism, that splits the image into red, green and blue components. Each of the three CCDs is arranged to respond to a particular color. Some semi-professional digital video camcorders (and all professionals) use this technique. Since a high-resolution CCD chip is very expensive as of 2005, a 3CCD high-resolution still camera would be beyond the price range even of many professional photographers. There are some high-end still cameras that use a rotating color filter to achieve both color-fidelity and high-resolution. These multi-shot cameras are rare and can only photograph objects that are not moving.

Competing technologies

Recently it has become practical to create an Active Pixel Sensor (APS) using the CMOS manufacturing process. Since this is the dominant technology for all chip-making, CMOS image sensors are cheap to make and signal conditioning circuitry can be incorporated into the same device. The latter advantage helps mitigate their greater susceptibility to noise, which is still an issue, though a diminishing one. CMOS sensors also have the advantage of lower power consumption than CCDs.

External links

- [http://www.olympus-biosystems.com/templates_eng/bio_imaging/glossary.html Digital imaging glossary]
- [http://www.nezumi.demon.co.uk/photo/bayer/bayer.htm Bayer masks]
- CCD vendors
- [http://www.dalsa.com/ Dalsa]
- [http://www.e2v.com/ e2v technologies]
- [http://www.fairchildimaging.com/ Fairchild Imaging]
- [http://sales.hamamatsu.com/assets/applications/SSD/Characteristics_and_use_of__FFT-CCD.pdf Hamamatsu Photonics Characteristics and use of FFT-CCD ]
- [http://www.kodak.com/ Kodak]
- [http://www.panasonic.co.jp/global/ Panasonic]
- [http://www.sony.com/ Sony]
- [http://www.ti.com/ Texas Instruments]
- [http://www.toshiba.com/ Toshiba] Category:Integrated circuits Category:Image processing Category:Detectors ko:CCD ja:CCDイメージセンサ

DWDM

:The original version of this article was based on FOLDOC, with permission In fiber optic telecommunications, wavelength-division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fibre by using different wavelengths (colours) of laser light to carry different signals. This allows for a multiplication in capacity, in addition to making it possible to perform bidirectional communications over one strand of fibre. The term wavelength-division multiplexing is commonly applied to an optical carrier (which is typically described by its wavelength), whereas frequency-division multiplexing typically applies to a radio carrier (which is more often described by frequency). However, since wavelength and frequency are inversely proportional, and since radio and light are both forms of electromagnetic radiation, the two terms are closely analogous.

WDM systems

A WDM system uses a multiplexer at the transmitter to join the signals together, and a demultiplexer at the receiver to split them apart. With the right type of fibre you can have a device that does both at once, and can function as an optical add-drop multiplexer. The optical filtering devices used in the modems are usually etalons, stable solid-state single-frequency Fabry-Perot interferometers. The first WDM systems combined two signals and appeared around 1985. Modern systems can handle up to 160 signals and can expand a basic 10 Gbit/s fibre system to a theoretical total capacity of over 1.6 Tbit/s over a single fiber pair. WDM systems are popular with telecommunications companies because they allow them to expand the capacity of the network without laying more fibre. By using WDM and optical amplifiers, they can accommodate several generations of technology development in their optical infrastructure without having to overhaul the backbone network. Capacity of a given link can be expanded by simply upgrading the multiplexers and demultiplexers at each end. This is often done by using optical-to-electrical-to-optical translation at the very edge of the transport network, thus permitting interoperation with existing equipment with optical interfaces. Most WDM systems operate on single mode fibre optical cables, which have a core diameter of 9 µm. Certain forms of WDM can also be used in multi-mode fibre cables (also known as premises cables) which have core diameters of 50 or 62.5 µm. Early WDM systems were expensive and complicated to run. However, recent standardization and better understanding of the dynamics of WDM systems have made WDM much cheaper to deploy. Optical receivers, in contrast to laser sources, tend to be wideband devices. Therefore the demultiplexer must provide the wavelength selectivity of the receiver in the WDM system.

Coarse WDM

WDM systems are divided into two market segments, dense and coarse WDM. Systems with more than 8 active wavelengths per fibre are generally considered Dense WDM (DWDM) systems, while those with fewer than eight active wavelengths are classed as coarse WDM (CWDM). CWDM and DWDM technology are based on the same concept of using multiple wavelengths of light on a single fiber, but the two technologies differ in the spacing of the wavelengths, number of channels, and the ability to amplify signals in the optical space. The Ethernet LX-4 physical layer standard is an example of a CWDM system in which four wavelengths near 1310 nm, each carrying a 3.125 gigabit-per-second data stream, are used to carry 10 gigabits per second of aggregate data. CWDM is also been used in cable television networks, where different wavelengths are used for the downstream and upstream signals. In these systems, the wavelengths used are often widely separated, for example the downstream signal might be at 1310 nm while the upstream signal is at 1550 nm.

Dense WDM

The introduction of the ITU-T G.694.1 frequency grid in 2002 has made it easier to integrate WDM with older but more standard SONET systems. (I don't have the details at hand, but I believe it specifies a 200 GHz frequency grid, with 100 GHz channel spacing as a refinement). Today's DWDM systems use 50 GHz or even 25 GHz channel spacing for up to 160 channel operation. Recently the ITU has standardized a 20 nanometre channel spacing grid for use with CWDM, using the wavelengths between 1310 nm and 1610 nm. Many CWDM wavelengths below 1470 nm are considered "unusable" on older G.652 spec fibres, due to the increased attenuation in the 1310-1470 nm bands. Newer fibres which conform to the G.652.C and G.652.D standards, such as Corning SMF-28e and Samsung Widepass nearly eliminate the "water peak" attenuation peak and allow for full operation of all twenty ITU CWDM channels in metropolitan networks. For more information on G.652.C and .D compliant fibres please see the links at the bottom of the article: DWDM systems are significantly more expensive than CWDM because the laser transmitters need to be significantly more stable than those needed for CWDM. Precision temperature control of laser transmitter is required in DWDM systems to prevent "drift" off a very narrow centre wavelength. In addition, DWDM tends to be used at a higher level in the communications hierarchy, for example on the Internet backbone and is therefore associated with higher modulation rates, thus creating a smaller market for DWDM devices with very high performance levels, and corresponding high prices. In another word, they are needed in small numbers and therefore not possible to amortize their development cost among a large number of transmitters. Note: The term "Lambda" is also used interchangeably when referencing a specific wavelength of light. External Links:
- [WDM Blog- Daily updates on the business and technology of wavelength division multiplexing http://www.wdmblog.com]
- [http://www.google.com/search?num=100&hl=en&q=G.652.C Google Search: G.652.C]
- [http://www.google.com/search?num=100&hl=en&q=G.652.D Google Search: G.652.D]
- [Lucent Technologies http://www.lucent.com/search/glossary/l-definitions.html#Lambda Services]

Kolibrit

Kolibrit (Trochilidae) ovat pieniä värikkäitä lintuja jotka pystyvät lentämään paikallaan ilmassa räpyttämällä siipiään kiivaasti (15-80 lyöntiä minuutissa).

Levinneisyys

Kolibreja elää Etelä-, Keski- ja Pohjois-Amerikassa.

Ravinto

Kolibrit imevät pitkällä nokallaan mettä kukista, varsinkin punaisista kukista. Ne syövät myös hyönteisiä.

Lajit

Kolibreita on yli 330 lajia. Kimalaiskolibri Mellisuga helenae painaa 1.8 grammaa ja on maailman pienin lintu. Luokka:Linnut ja:ハチドリ

pozycjonowanie darmowe mp3 zbiorniki tworzywowe �mieszne zdj�cia Dorota Rabczewska

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