Tag : Display

14:9

A picture aspect ratio that has been used to present 16:9 images on 4:3 screens. It avoids showing larger areas of black above and below letterboxed pictures but does include more of the 16:9 image than displaying at 4:3. As the population of 16:9 TV screens increases and 4:3 declines, so the use of 14:9 continues to diminish.

4:3

The aspect ratio of traditional PAL and NTSC television pictures, originally chosen to match the 35mm film format of the time. All broadcast television pictures were 4:3 until the introduction of high definition when a wider image was considered to be more absorbing for viewers. For display tube manufacturers the most efficient aspect ratio would be 1:1 (square) as this is inherently the strongest shape, uses less glass and weighs less. More glass is used in 16:9 tubes so they are more expensive to produce. Such restraints do not apply to today’s TV screens and monitors using LED and Plasma technology.

Active line

The part of a television line that carries picture information. The remainder of the whole line time is mainly reserved to allow scans to reset to the start of the next line in camera tubes and CRT screens. Although the imaging and display technologies have moved on to chips and panels, there remains a break (line blanking) in the sampling of digital TV as in ITU-R BT.601 and ITU-R BT 709. These ‘spaces’ carry data for the start of lines and pictures, as well as other information such as embedded audio tracks.

See also: Active picture

Active picture

The area of a TV frame that carries picture information. Outside the active area there are line and field, or frame, blanking which roughly, but not exactly, correspond to the areas defined for the original 525- and 625-line analog systems. In digital versions of these, the blanked/active areas are defined by ITU-R BT.601, SMPTE RP125 and EBU-E.

For 1125-line HDTV (1080 active lines), which may have 60, 30, 25 or 24 Hz frame rates (and more), the active lines are always the same length: 1920 pixel samples at 74.25 MHz, a time of 25.86 microseconds, defined in SMPTE 274M and ITU-R.BT 709-4. Only their line blanking differs so the active portion may be mapped pixel-for-pixel between these formats.

DTV standards tend to be quoted by only their active picture content, eg 1920 x 1080, 1280 x 720, 720 x 576, as opposed to analog where the whole active and blanked areas are included, such as 525 and 625 lines. For both 625 and 525-line formats active line length is 720 luminance samples at 13.5 MHz = 53.3 microseconds. In digital video there are no half lines as there are in analog. The table below shows blanking for SD and some popular HD standards.

Analog Format625/50525/601125/60I1125/50I1125/24P
Active lines 576487108010801080
Field 1 lines2419222245/frame
Field 2 lines25192323-
Line Blanking12μs10.5μs3.8μs9.7μs11.5μs

Active Picture

 

Anamorphic

Generally refers to the use of 16:9 aspect ratio pictures in a 4:3 SDTV system. For example, anamorphic supplementary lenses are used to change the proportions of the captured image to 16:9. These horizontally squashed images can then fit onto the surface of a 4:3 sensor. Outputs from 16:9 cameras and telecines produce an ‘anamorphic’ signal which is electrically the same as when working with 4:3 images, but will appear horizontally squashed if displayed at 4:3 aspect ratio.

The alternative way of carrying 16:9 pictures within 4:3 systems is letterbox. Letterbox has the advantage of showing the correct 16:9 aspect ratio on 4:3 displays, however the vertical resolution is then less than when using 16:9 anamorphic.

Cinema film is sometimes printed with anamorphic frames, allowing widescreen presentations from, typically, 4:3 images projected via a suitable anamorphic lens.

The major use of anamorphic in TV occurred when 4:3 SD cameras were used to capture 16:9 images. Now 16:9 cameras are widely available, the use of anamorphic techniques is increasingly rare.

See also: Aspect ratio – of pictures

ARC

Aspect Ratio Converters change picture aspect ratio, usually between 16:9 and 4:3. Other aspect ratios may be also allowed for, such as 14:9, and custom values are often available. Technically, the operation involves independent horizontal and vertical resizing and there are a number of choices for the display of 4:3 originals on 16:9 screens and vice versa (e.g. letterbox, pillar box, full height and full width). Whilst changing the aspect ratio of pictures, the objects within should retain their original shape with the horizontal and vertical axes expanded or contracted equally.

See also: Aspect ratio

Black and Burst

A PAL or NTSC video signal with no picture (black). The signal comprises line and field sync pulses as well as the color ‘burst’ before the start of each active TV line. It was widely used as an accurate timing reference for analog 626 and 525-line color equipment. You might have thought it has passed into history, but you would be wrong. Black and burst is still widely used as a sync reference timing signal for digital formats including SD, HD and UHD.

See also: 2.25 MHz, IEEE 1588, Tri-level sync

D-ILA

Digital Direct Drive Image Light Amplifier. Technology developed by Hughes-JVC for video projection up to large screen size for home theaters. Digital images are displayed by a CMOS chip which has a reflective liquid-crystal surface where electronic signals are directly addressed to the image modulator. The image pixel information is addressed to a matrix of ‘transistor’ cells beneath the liquid crystal which directly responds to voltage level; the gray scale is determined by the voltage set on each pixel. The reflection of the projector lamp light focused on the chip produces an image. The technology has been used up to cinema-screen size and can display 4K resolution.

DCI

Digital Cinema Initiatives, LLC was formed in 2002 with members including Disney, Fox, MGM, Paramount, Sony Pictures Entertainment, Universal and Warner Bros. Studios. Its purpose was to establish and document specifications for an open architecture for Digital Cinema components that ensures a uniform and high level of technical performance, reliability and quality control. It published the Digital Cinema System Specification in July 2005 (freely available at their website) and established a set of technical specifications that allowed the industry to roll-out Digital Cinema. It is a measure of the DCI’s success that now well over half of the world’s cinemas are digital.

There are three levels of images, all with a 1:1 pixel aspect ratio, 12-bit 4:4:4 sampling in X´Y´Z´ color space.

LevelPicture SizeAspect RatioFrame Rate
14096x21601.89624Hz
22048x10801.89648Hz
32048x10801.89624Hz

The specification includes requirements for JPEG 2000 image compression, X´Y´Z´ color space and a maximum playout bit rate of 250 Mb/s. To prevent piracy by copying the media files there is AES 128 encryption (Advanced Encryption Standard able to use keys of 128, 192, and 256 bits to encrypt and decrypt data in blocks of 128 bits). There is also forensic marking to deter and trace the bootlegger’s camcorder pointed at the screen. Such schemes include Philips’ forensic watermarking or Thomson’s NexGuard watermarking.

DSM → DCDM → DCP → DCDM* → Image and Sound

DCI describes a workflow from the output of the feature post production or DI, termed the Digital Source Master (DSM), to the screen. The Digital Cinema Distribution Master (DCDM) is derived from the DSM by a digital cinema post production process, and played directly into a digital cinema projector and audio system for evaluation and approval.

The approved DCDM is then compressed, encrypted and packaged for distribution as the Digital Cinema Package (DCP). At the theater, it is unpackaged, decrypted and decompressed to create a DCDM* with images visually indistinguishable from those of the original DCDM.

Website: www.dcimovies.com

 

Digital Cinema

Refers to the digital distribution and projection of cinema material. With virtually all films now using the DI process, the next step is to distribute and replay digital material. Thanks to the DCI’s Digital Cinema System Specification (July 2005), a set of standards is in place and the majority of cinemas worldwide are now converted to digital.

The digital cinema chain includes DCI-compliant equipment for mastering which generally uses JPEG 2000 compression encoding and high strength encryption. At the cinema players and digital projectors include decryption, image decoding and predominantly DLP, D-ILA technologies to display the images and provide consistently high quality viewing on large screens – no matter how many times the movie is shown.

Digital Cinema offers new methods for duplication, high-level security, efficient duplication distribution and greater flexibility. In addition, stereo cinema (a.k.a. 3D) is easy to set up and present using just one projector (not two), along with a left and right eye selective viewing system.

Many digital cinemas can also show live (or recorded) footage originating in HDTV. These presentations typically include live sports, big events and theatrical performances from around the world, creating new markets for cinemas.

See also: DCI, DLP-cinema, D-ILA, SXRD

Display resolutions

The computer industry has developed a series of display resolutions which span television’s SD, HD and UHD, a selection is listed below. The availability of hardware to support these resolutions has, and will continue to benefit television and digital film.

All use square pixels and none correspond exactly to television formats so attention to size and aspect ratio is needed when using computer images on TV and vice versa.

TypeSizeM PixelsAspect ratio 
VGA640 x 4800.314:31.33
SVGA800 x 6000.484:31.33
XGA1024 x 7680.794:31.33
SXGA1280 x 10241.315:41.25
UXGA1600 x 12802.055:41.25
WUXGA1920 x 12002.316.101.60
QXGA2048 x 15363.154:31.33
QSXGA2560 x 20485.244:31.33
WQSXGA3200 x 20486.5516.101.56
WQUXGA3840 x 24009.2216.101.56
4K4096 x 23049.4416:91.77
HXGA4096 x 307212.584:31.33
WHUXGA7680 x 480036.8616.101.56

Notes
Video SDTV                 720 x 576 (not square pixels)
720 x 480 (not square pixels)

Video HDTV                1920 x 1080
2K DCI cinema            2048 x 1080
2K digital film             2048 x 1556
4K TV (UHD1)              3840 x 2160
4K DCI cinema            4096 x 2160
4K digital film             4096 x 3112
8K TV (UHD2)              7680 x 4320

*The image area of Full Frame film 35 mm images is usually scanned to occupy 2048 x 1536 pixels (4K – 4096 x 3072). The extra 20 (40) lines scan the black strip between successive frames which only carries image information if film is shot with an open gate.

See also: 2K, Aspect ratio

Website: www.fourmilab.ch/documents/howmanydots

DLP

(Texas Instruments Inc.) Digital Light Processing is the projection and display technology which uses digital micromirror devices (DMD) as its light modulator. It is a collection of electronic and optical subsystems which enable picture information to be decoded and projected as high-resolution digital color images. DLP technology enables the making of very compact, high brightness projectors. Over 100,000 movie theater screens worldwide use its DLP Cinema technology, and many more DLP-driven systems are used by consumers.

The technology also allows for higher frame rates (beyond 24f/s) and stereo 3D presentations.

See also: DMD

Website: www.dlp.com

DMD

(Texas Instruments Inc.) Digital Micromirror Device. A silicon CMOS integrated circuit used to modulate light in a wide variety of applications. The most common use is in digital projection systems where one or more devices are used to create high quality color images.

The device is a memory circuit whose elements are arranged in a display format array matrix. Each element has a minute square hinged aluminum mirror on its front which can tilt about its diagonal axis. The electrical charge in the memory cell causes the mirror to deflect from one tilt position to the other. By changing the memory data, the mirror can be switched very rapidly (about 15kHz) to create pulses of light whose duration causes the pixel to appear at a particular brightness, so producing the display of gray scales. DMDs are produced at different sizes according to the resolution required. The smallest contains over 500,000 mirrors. Devices for 2K (2048 x 1080) and 4K (4096 x 2160) DCI formats are widely used in digital cinema projectors as well as in home cinemas.

See also: DLP

Website: www.dlp.com

Full HD

Full HD is a term describing video at 1920 x 1080 resolution. Generally this appears as one of the many logos stuck on a new flat panel TV set or screen that can display all the pixels of 1920 x 1080 images supplied from HD sources such as broadcast transmissions and HD DVD and Blu-ray Discs.

The panels only use progressive scans so they are showing 50P and 59.94P frame rates. The logo can also appear on other consumer products such as camcorders using the 1920 x 1080 image size.

IDTV

Integrated Digital TV receiver. For viewers to receive DTV services they require a receiver either in the form of a new television set with the tuner and digital decoder built in (IDTV) or a set-top box. IDTVs typically include provision for all widely available terrestrial DTV services, so cable and satellite still require a set-top box. Note that although the set may be able to receive HD the screen may not be able to display the full sized 1920 x 1080 HD picture. In this case processing is included to re-size the pictures to fit the screen.

See also: IRD, Table 3

Letterbox

A method used to show higher aspect ratio (e.g. 16:9) images on a low aspect ratio (e.g. 4:3) display. While all the contents of the pictures can be seen there are strips of (usually) black above and below the picture which some people do not like. Now that nearly all viewers have 16:9 screens, the use of letterbox is passing into history.

Letterbox

See also: 14:9, Anamorphic, ARC

OLED

Organic Light Emitting Diode technology is used to make displays for video, computer screens, mobile devices, and more. Light is generated when a voltage is applied across an emissive electroluminescent layer of an organic (containing carbon) semiconductor compound via two electrode layers. The brightness of the light from each diode is varied according to the video input – unlike ‘LED’ screens that are predominant in the current screen market. Here the LEDs provide a white backlight behind an LCD (liquid crystal display) that works as a red, green and blue light filter for each pixel that is controlled by the input image (video, etc).

The OLED technology offers a number of benefits over LED screen technology. As there is no backlight, when the OLEDs are switched off there is no light emitted. Black really looks black, and the screens are specified with a very high contrast ratio. They also offer a faster response time, wider viewing angles and larger color gamuts. As a result the images look very good and they they are often used as monitors. As it is easy to put the OLEDs very close together it is possible to make very small screens that deliver full resolution images – useful for viewfinders, handheld devices, phone, etc. An OLED screen’s power consumption is less than equivalent LED screen as almost all the light generated is visible, none absorbed in filters. The screens can be very thin. An early 50-inch consumer model was boasting 6mm thickness. The screens can be bent, and some manufacturers are offering curved screens. Perhaps OLEDs may be used to make a roll-up screen.

On the downside, OLED screens are still offered at a substantial price premium over LED versions. Also it is said that the life expectancy of OLED screens is considerably less than that of LEDs, mainly due to the relatively short life of the blue OLEDs. Work continues to improve that area.

OLED screens have been produced for a number of years but only recently have been widely available in the consumer market.

See also: Quantum dot, SED

Projectors (digital)

Digital projectors input digital images and project them onto cinema-sized screens. Huge advances in this technology in recent years have been one of the driving forces behind digital cinema. For post production or DI, many houses offer big screens for customers to see what the final cinema experience will look like. Among the prominent projection technologies in the large projector area are D-ILA from JVC, SXRD from Sony and DLP from Texas Instruments. These projectors work by shining the projector light at reflective chips that display the image, so modulating the light that is reflected towards the projector’s lens. Movies are mostly made using 4K resolution, delivering great detail, without film’s scratches, dirt and weave, the audience is treated to consistent high quality results. Many digital cinema players and projectors can deliver 3D.

There is a wide range of digital projectors now available that are used for business presentations as well as for home cinema.

See also: Color management, Digital Cinema, DLP, D-ILA, SXRD

Quantum dot (QD)

Quantum dot is a relatively new display technology for television screens. QD are microscopic particles that emit light when electricity is applied, or when light is shone on them. The light’s color is very stable and relates to the QD’s size. Of late, they have been applied to screen technology in two ways.

One is to use them as a backlight for LCD screens. Currently LED screens use LEDs as the backlight, and an LCD filter to control the brightness of each screen ‘dot’ (not quantum!). QD backlight uses just a blue LED light which is converted by QDs to reasonably pure red and green – very close to the required red, blue and green – so far less light is absorbed in the RGB filters behind the LCD screen, so providing more useful light (brighter pictures) and more accurate colors, and it does not drift.

The other type of QD screen uses QD-based LEDs to directly emit the screen light – as OLEDs screens do now. However OLED screens remain at high prices and there is some fear of quality degradation over time. QD-LED color can be accurately tuned in manufacture and is has a narrow spectrum. It does not drift and is not known to degrade. Amazon’s Kindle Fire HDX tablet uses QD technology, as did Sony in 2013 with its Triluminous screens.

SDTV

Standard Definition Television. Digital television systems that operate using standard definition video formats, i.e. 720 x 480/59.94I or 720 x 576/50I. Both these may carry 4:3 or 16:9 images, and in all cases, the pixels are not square. All HDTV and UHDTV digital standards describe square pixels.

Second Screen

Using a tablet or smart phone to access more background information, or to add comments, about what you are watching on TV is said to be using a ‘second screen’. Some productions offer an app and access to more relevant material to add to the experience – beyond just the passive watching of TV.

Smart TV

A television set that includes an internet connection, some computing power and a UI to access the ‘Smart’ functions – including internet browsing. Popular uses include accessing ‘catch-up TV’ services such as Comcast’s Xfinity and the BBC’s iPlayer. Smart TVs now make up nearly 50 percent of the set population in the USA. However, the use of the internet beyond the catchup services is reported to be in decline, with the UI cited as a major cause.

StEM

In 2004 the Standard Evaluation Material was created by the ASC (American Society of Cinematographers) and DCI to assess the quality of possible digital cinema picture compression systems and formats against the best that film can offer. It is about 25 minutes of material from multiple film formats. At that time the most widely used compression system for video was MPEG-2 and some said the StEM film was an ‘MPEG breaker’ with smoky scenes and movement that would challenge that compression system. The next year DCI recommended JPEG 2000, an entirely different compression system to the established DCT-based JPEG.

Super Hi-Vision (SHV)

Also known as 8K UHD, pioneered by the Japanese broadcaster NHK this is a very large format television system with a pictures size of 7680 x 4320 pixels. It is proposed to run at frame rates from 23.98 to 120 Hz and start broadcasting by 2020. SHV can also support a 22.2 sound system with 22 speakers and two woofers.

See also: ITU-R BT.2020, UHD

SXRD

Silicon X-tal (crystal) Reflective Display, a reflective liquid crystal micro-display from Sony used in the first commercially available 4K-sized projectors. The display chip has 4096 x 2160 pixels on one-and-a-half inches (diagonal) of a silicon chip. The design maintains a uniform, ultra-thin liquid crystal cell gap without any spacers in the image area, contributing to contrast performance, claimed as 4000:1. Its Vertically Aligned Nematic (VAN) liquid crystal changes state fast enabling speeds up to 200 f/s while minimizing image smear. HDTV-sized SXRD chips have been used in Sony consumer products, including a front projector and rear projection televisions up to 70 inches.

See also: Projectors (digital)

Versioning

In today’s multimedia world there is much demand for many version of a finished production. This business has ballooned. Historically versioning involved making copies from the edited and graded master to various videotape formats and, via a standards converter, to other video standards (e.g. NTSC to PAL). Now technical variations involve many more formats being supplied, including Web, mobile, HD and SD TV, DVD and cinema, as well as a variety of display systems including LED, LCD, Plasma and digital cinema. Aside from the technical needs, other requirements such as commercial, language and religious influences are among the many factors that can be causes for more yet versions.

Versioning is big business, as the number of versions can run to many tens and involve much more than simply making copies of the master. For example, work may involve re-grading to suit different viewing conditions, re-insertion of text or images to suit different regions or countries, pricing (for commercials) adding or removing shots or scenes for censoring, etc. Generally, for this to be done efficiently and effectively requires nonlinear editing in an uncommitted environment; where original footage and all the post processes that produced the master are available for recall and allow direct access to further adjustments, to re-make the result in a short time.

Video projection

Video projector technology can now show up to 4K images (4096 x 2160) on large cinema screens. Such technology is a major part of Digital Cinema development. There are two major technologies used for large-scale projection, D-ILA and DLP Cinema.

See D-ILA, DLP cinema

Widescreen

A TV picture that has an aspect ratio wider than 4:3 – usually 16:9 – while still using the normal 525/60 or 625/50 or SD video. 16: 9 is also the aspect ratio used for HDTV. There is an intermediate scheme using 14:9 which is found to be more acceptable for those still using 4:3 displays. Widescreen is used on some analog transmissions as well as many digital transmissions. The mixture of 4:3 and 16:9 programming and screens has greatly complicated the issue of safe areas.

WYSIWYG

What You See Is What You Get. Usually, but not always, referring to the accuracy of a screen display in showing how the final result will look. For example, a word processor screen showing the final layout and typeface that will appear from the printer. Or in an edit suite; does the monitor show exactly what will be placed on the master recording? This subject requires more attention as edited masters are now commonly output to a wide variety of ‘deliverables’ such as SD, HD, and UHD video, DVD, cinemas, the internet and social media… Issues such as color, gamma and display aspect ratio may need consideration.

See also: Color Management