VIDEO RESOLUTION
The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube (CRT) and flat panel or projection displays using fixed picture-element (pixel) arrays.
One use of the term “display resolution” applies to fixed-pixel-array displays such as plasma display panels (PDPs), liquid crystal displays (LCDs), Digital Light Processing (DLP) projectors, or similar technologies, and is simply the physical number of columns and rows of pixels creating the display (e.g., 1920×1200). A consequence of having a fixed grid display is that, for multi-format video inputs, all displays need a “scaling engine” (a digital video processor that includes a memory array) to match the incoming picture format to the display.
Standards
Televisions are of the following resolutions:
- Standard-definition television (SDTV):
- 480i (NTSC uses an analog system of 486i split into two interlaced fields of 243 lines)
- 576i (PAL, 720×576 split into two interlaced fields of 288 lines)
- Enhanced-definition television (EDTV):
- High-definition television (HDTV):
- 720p (1280×720 progressive scan)
- 1080i (1920×1080 split into two interlaced fields of 540 lines)
- 1080p (1920×1080 progressive scan)
Computer monitors have higher resolutions than most televisions. As of July 2002[update], 1024×768 eXtended Graphics Array was the most common display resolution.[1][2] Many web sites and multimedia products were re-designed from the previous 800×600 format to the higher 1024×768-optimized layout.
The availability of inexpensive LCD monitors has made the 5:4 aspect ratio resolution of 1280×1024 more popular for desktop usage. Many computer users including CAD users, graphic artists and video game players run their computers at 1600×1200 resolution (UXGA, Ultra-eXtended) or higher if they have the necessary equipment. Other recently available resolutions include oversize aspects like 1400×1050 SXGA+ and wide aspects like 1280×720 WXGA, 1600×768(750) UWXGA, 1680×1050 WSXGA+, and 1920×1200 WUXGA. A new HD resolution of 2560×1600 WQXGA has been released mainly in 30″ LCD monitors. Special monitors for medical diagnostic work are using 3280×2048 WQSXGA, which is the current maximum resolution available in a single monitor. The most common computer display resolutions are as follows:[3]
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| Code |
Name |
Aspect ratio |
Width |
Height |
% of Steam users |
| VGA |
Video Graphics Array |
4:3 |
640 |
480 |
n/a |
| SVGA |
Super Video Graphics Array |
4:3 (12:9) |
800 |
600 |
n/a |
| XGA |
eXtended Graphics Array |
4:3 |
1024 |
768 |
12.36% |
| XGA+ |
eXtended Graphics Array Plus |
4:3 |
1152 |
864 |
2.22% |
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w_2,133:1 (32:15) |
1280 |
600 |
* |
| HDTV |
Standard High Definition Television |
16:9 |
1280 |
720 |
* |
| WXGA |
Widescreen eXtended Graphics Array |
5:3 (15:9) |
1280 |
768 |
0.72% |
| WXGA |
Widescreen eXtended Graphics Array |
8:5 (16:10) |
1280 |
800 |
6.44% |
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15:10 |
1280 |
854 (853,333) |
* |
| SXGA (UVGA) |
Super eXtended Graphics Array |
4:3 |
1280 |
960 |
1.54% |
| SXGA |
Super eXtended Graphics Array |
5:4 |
1280 |
1024 |
19.10% |
| WXGA |
Wide XGA resolution |
16:9 |
1360 |
768 |
4.50% |
| WSXGA |
Widescreen Super eXtended Graphics Array |
8:5 (16:10) |
1440 |
900 |
10.53% |
| HD+ |
High Definition Plus |
16:9 |
1600 |
900 |
* |
| UXGA |
Ultra eXtended Graphics Array |
4:3 |
1600 |
1200 |
1.01% |
| WSXGA+ |
Widescreen Super eXtended Graphics Array Plus |
8:5 (16:10) |
1680 |
1050 |
18.23% |
| HDTV |
Full High Definition Television |
16:9 |
1920 |
1080 |
9.68% |
| WUXGA |
Widescreen Ultra eXtended Graphics Array |
8:5 (16:10) |
1920 |
1200 |
5.93% |
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* Other |
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3.42% |
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VIDEO FRAME
In film, video production, animation, and related fields, a frame is one of the many still images which compose the complete moving picture. Historically, these were recorded on a long strip of photographic film, and each image looked rather like a framed picture when examined individually, hence the name.
When the moving picture is displayed, each frame is flashed on a screen for a short time (nowadays, usually 1/24th, 1/25th or 1/30th of a second) and then immediately replaced by the next one. Persistence of vision blends the frames together, producing the illusion of a moving image.
The video frame is also sometimes used as a unit of time, being variously 1/24, 1/25 or 1/30 of a second, so that a momentary event might be said to last 6 frames.
The frame rate, the rate at which sequential frames are presented, varies according to the video standard in use. In North America and Japan, 30 frames per second is the broadcast standard, with 24 frame/s now common in production for high-definition video. In much of the rest of the world, 25 frame/s is standard.
In film projection, 24 frame/s is the norm, except in some special venue systems, such as IMAX, Showscan and Iwerks 70, where 30, 48 or even 60 frame/s have been used. Silent films and 8 mm amateur movies used 16 or 18 frame/s.
Frame rates in film and television
There are currently (2011) three main frame rate standards in the TV and movie-making business: 24p, 25p, and 30p. However there are many variations on these as well as newer emerging standards.
- 50i (50 interlaced fields = 25 frames) is the standard video field rate per second for PAL and SECAM television.
- 60i (actually 59.94, or 60 x 1000/1001 to be more precise; 60 interlaced fields = 29.97 frames) is the standard video field rate per second for NTSC television (e.g. in the US), whether from a broadcast signal, DVD, or home camcorder. This interlaced field rate was developed separately by Farnsworth and Zworykin in 1934, and was part of the NTSC television standards mandated by the FCC in 1941. When NTSC color was introduced in 1953, the older rate of 60 fields per second was reduced by a factor of 1000/1001 to avoid interference between the chroma subcarrier and the broadcast sound carrier.
- 30p, or 30-frame progressive, is a noninterlaced format and produces video at 30 frames per second. Progressive (noninterlaced) scanning mimics a film camera’s frame-by-frame image capture. The effects of inter-frame judder are less noticeable than 24p yet retains a cinematic-like appearance. Shooting Video in 30p mode gives no interlace artifacts but can introduce judder on image movement and on some camera pans. The widescreen film process Todd-AO used this frame rate in 1954–1956.
- The 24p frame rate is also a noninterlaced format, and is now widely adopted by those planning on transferring a video signal to film. Film and video makers use 24p even if their productions are not going to be transferred to film, simply because of the on-screen “look” of the (low) frame rate which matches native film. When transferred to NTSC television, the rate is effectively slowed to 23.976 frame/s, and when transferred to PAL or SECAM it is sped up to 25 frame/s. 35 mm movie cameras use a standard exposure rate of 24 frames per second, though many cameras offer rates of 23.976 frame/s for NTSC television and 25 frame/s for PAL/SECAM. The 24 frame/s rate became the de facto standard for sound motion pictures in the mid-1920s.[3]
- 25p is a video format that runs twenty-five progressive frames per second. This frame rate derives from the PAL television standard of 50i (or 50 interlaced fields per second). Film and Television companies use this rate in 50 Hz regions for direct compatibility with television field and frame rates. Conversion for 60 Hz countries is enabled by slowing down the media to 24p then converted to 60 Hz systems using pull down. While 25p captures half the temporal resolution or motion that normal 50i PAL registers, it yields a higher vertical special resolution per frame. Like 24p, 25p is often used to achieve “cine”-look, albeit with virtually the same motion artifacts. It is also better suited to progressive-scan output (e.g., on LCD displays, computer monitors and projectors) because the interlacing is absent.
- 50p and 60p is a progressive format used in high-end HDTV systems. While it is not technically part of the ATSC or DVB broadcast standards, it is rapidly gaining ground in the areas of set-top boxes and video recordings.
- 720p is currently an experimental progressive scan format. Major institutions such as Snell have demonstrated 720p72 pictures as a result of earlier analogue experiments, where 768 line television at 75 Hz looked subjectively better than 1150 line 50 Hz progressive pictures with higher shutter speeds available (and a corresponding lower data rate). Modern cameras such as the Red, can use this frame rate to produce slow motion replays at 24 frame/s. Douglas Trumbull who undertook experiments with different frame rates which led to the Show scan film format, found that 72 frame/s was the maximum frame rate at which emotional impact peaked for viewers. 72 frame/s is the maximum rate available in the WMV video file format.
Higher frame rates including 300 Hz have been tested by BBC R&D over concerns with sports and other broadcasts where fast motion with large HD displays could have a disorientating effect on viewers. 300 frame/s can be converted to both 50 and 60 Hz transmission formats without major issues.
Owing to their flexibility, software-based video formats can specify arbitrarily high frame rates, and many (cathode ray tube) consumer PC monitors operate at hundreds of frames per second, depending on selected video mode. LCD screens are usually 24, 25, 50, 60, or 120 frame/s.
