Display resolution
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The display resolution of a digital television or computer display can be an ambiguous term especially as displayed resolution is controlled by different factors in picture-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 flat-panel plasmas (PDPs), LCDs, front and rear projectors using LCD, DLP or similar technologies and is simply the physical number of columns and rows of pixels creating the display (eg, 852x480; 1368x768 etc). A consequence of having a fixed grid display is that for multiformat 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.
Some manufacturers also use this term to indicate a range of input formats that the display's input electronics will accept and often include formats greater than the screen's native grid size even though they have to be down-scaled to match the screen's parameters- (eg. accepting a 1920x1080 input on a display with a native 1368x768 pixel array). In the case of television inputs, many manufacturers will take the input and zoom it out to "overscan" the display by as much as 5% so input resolution isn't necessarily display resolution.
The eye's perception of "display resolution" can be affected by a number of factors - see Image resolution and Optical resolution. One factor is the display screen's rectangular shape, which is expressed as the ratio of the physical picture width to the picture height.
This is known as the aspect ratio. A screen's physical aspect ratio and the individual pixels' aspect ratio may not necessarily be the same. An array of 1280x720 on a 16:9 progressive scanned display has square pixels.
An example of pixel shape affecting "resolution" or peceived sharpness: if you had 2 similar displays, both the same picture height and both having a 720x576 pixel array but one a 16:9 wide screen, the other a 4:3 screen and you displayed the same 720x576 4:3 picture on both, apart from the picture being stretched on the 16:9 display, the 4:3 screen will look the sharper.
While some CRT based displays may use digital video processing that involves image scaling using memory arrays ultimately "Display resolution" in CRT type displays are affected by different parameters such as spot size and focus, astigmatic effects in the display corners, the color phosphor pitch shadow mask or trinitron in color displays and the video bandwidth.
Applying mainly to CRT displays the way the lines or rows are displayed will also affect the perceived resolution in the vertical direction. This relates to the differences produced by interlace or progressive scanning and now by the use of memory to hold each pixel's displayed brightness values between picture refreshes.
Overview
Analog television systems use interlace scanning with two sequential scans (50 or 60 fields per second), one with the odd numbered lines, the other with the even numbered lines to give a complete picture (25 or 30 frames per second). This is done to save transmission bandwidth but a consequence is that in picture tube (CRT) displays, the full vertical resolution cannot be realised. For example, the maximum detail in the vertical direction would be for adjacent lines to be alternately black then white. This is not a problem in a progressive display but an interlace display will have an unacceptable flicker or twitter at the slower frame rate. This is why interlace is unacceptable for fine detail such as computer word processing or spreadsheets. For television it means that if the picture is intended for interlace displays the picture must be vertically filtered to remove this objectional flicker with a reduction of vertical resolution to about 70%. So a 576 line PAL interlace display only has about 400 lines vertical resolution and 350 in the case of a 480 line NTSC interlace display. Similarly, 1080i HD interlaced video would need to be filtered to about 700 lines for an interlaced display. Any interlaced broadcast television pictures and for that matter DVDs are filtered to that vertical resolution to reduce the interline twitter on fine detail.Fixed pixel array displays such as LCDs, Plasmas, DLPs, LCoS, etc. need a "scaling" processor with frame memory, which depending on the processing system, effectively converts an incoming interlaced picture into progressive. A similar process occurs in a PC and its display with interlaced video (eg. from a TV tuner card). The downside is that interlace motion artifacts are almost impossible to remove resulting in horizontal "toothed" edges on moving objects.
Also in analog connected picture displays such as CRT TV sets, the horizontal scanlines are not divided into pixels, and therefore the horizontal resolution is related to the bandwidth of the luminance and chroma signals. For television, the analog bandwidth for luminance in standard definition should be flat to 5 MHz and in high definition, about 30 MHz.
Current Standards in Resolution
Currently 1024×768 (XGA/XVGA, eXtended), 1280×1024 (SXGA Super eXtended Graphics Array), and 1600×1200 resolution (UXGA, Ultra-eXtended) are the most common display resolutions. Many computer users, including CAD users and video game players, run their computers at 1600×1200 resolution (UXGA, Ultra-eXtended) or higher if they have the necessary equipment. When a computer display resolution is set higher than the physical screen resolution, some systems make the virtual screen scrollable over the physical screen, however, most CRT monitors will accept higher resolutions than their native resolution without scrolling. The true maximum resolution is calculated from the dot pitch. Few CRT manufacturers will quote the true native resolution in their documentation, but most LCD manufacturers do. With digital television and HDTV, vertical resolutions of 720 or 1080 scan lines are typical.Overscan
Most television display manufacturers "overscan" the pictures on their displays (CRTs and PDPs, LCDs etc.), so that the effective on-screen picture may be reduced from 720×576(480) to 680×550(450), for example. The size of the invisible area somewhat depends on the display device. Computer displays including projectors generally do not overscan.Evolution of Resolution Standards
Many personal computers introduced in the late 1970s and the 1980s were designed to use television sets as their display devices, making the resolutions dependent on the television standards in use, including PAL and NTSC. Picture sizes were usually limited in order to ensure the visibility of all the pixels in the major television standards and the broad range of television sets with varying amounts of overscan. The actual drawable picture area was therefore somewhat smaller than the whole screen, and was usually surrounded by a static-colored border. Also, the interlace scanning was usually omitted in order to provide more stability to the picture, effectively halving the vertical resolution in progress. 320×200 and 640×200 were relatively common resolutions in the era. In the PC world, these resolutions came to be used by the Color Graphics Adapter.The 640×480 resolution, introduced with the IBM PS/2 VGA and MCGA (multi-color) on-board graphics chips, was the standard resolution in the IBM PC compatibles from 1990 to around 1996, partly due to its ratio. 800×600 was the standard resolution until around 2000. Since then, 1024×768 has been the standard resolution. Many web sites and multimedia products are designed for this resolution. Most of today's computer games released during the "128-bit video game era", such as SimCity 4, do not support 640×480 at all. Microsoft Windows XP is designed to run at 800×600 minimum (although it is possible to select 640×480 in the Advanced Settings window, and an application is able to switch to any other mode). GNU/Linux, FreeBSD, and most Unix variants use The X Window System and can run at any desired resolution as long as the display and video card support it. The Apple's Mac OS and Mac OS X operating systems are able to run with most available display resolutions, although 800×600 is a reasonable minimum.
Common Display Resolutions
Computer Graphics
| Computer Standard | Resolution | Display Aspect Ratio | Pixels |
|---|---|---|---|
| VIC-II multicolor, IBM PCjr 16-color | 160×200 | 4:5 | 32,000 |
| TMS9918, ZX Spectrum | 256×192 | 4:3 | 49,152 |
| CGA 4-color, Atari ST 16 color, VIC-II HiRes, Amiga OCS NTSC LowRes | 320×200 | 8:5 | 64,000 |
| QVGA | 320×240 | 4:3 | 76,800 |
| Amiga OCS PAL LowRes | 320×256 | 5:4 | 76,800 |
| Black & white Macintosh (9") | 512×342 | 3:2 | 175,104 |
| Macintosh LC (12")/Color Classic | 512×384 | 4:3 | 196,608 |
| Atari ST 4 color, CGA mono, Amiga OCS NTSC HiRes | 640×200 | 16:5 | 128,000 |
| Amiga OCS PAL HiRes | 640×256 | 5:2 | 163,840 |
| EGA | 640×350 | 64:35 (approx. 9:5) | 224,000 |
| Atari ST mono, Amiga OCS NTSC interlaced | 640×400 | 8:5 | 256,000 |
| VGA and MCGA | 640×480 | 4:3 | 307,200 |
| Amiga OCS PAL interlaced | 640×512 | 5:4 | 327,680 |
| HGC | 720×348 | 60:29 (approx. 2:1) | 250,560 |
| MDA | 720×350 | 72:35 (approx. 2:1) | 252,000 |
| Apple Lisa | 720×360 | 2:1 | 259,200 |
| WGA | 800×480 | 5:3 | 384,000 |
| SVGA | 800×600 | 4:3 | 480,000 |
| XGA | 1024×768 | 4:3 | 786,432 |
| NeXTcube | 1120×832 | 35:26 (approx. 4:3) | 931,840 |
| XGA+ | 1152×864 | 4:3 | 995,328 |
| SXGA | 1280×1024 | 5:4 | 1,310,720 |
| WXGA | 1366×768 | 16:9 | 1,049,088 |
| WSXGA or WXGA+ | 1440×900 | 16:10 | 1,296,000 |
| SXGA+ | 1400×1050 | 4:3 | 1,470,000 |
| WSXGA | 1600×1024 | 25:16 | 1,638,400 |
| WSXGA+ | 1680×1050 | 16:10 | 1,764,000 |
| UXGA | 1600×1200 | 4:3 | 1,920,000 |
| WUXGA | 1920×1200 | 16:10 | 2,304,000 |
| QXGA | 2048×1536 | 4:3 | 3,145,728 |
| WQXGA | 2560×1600 | 16:10 | 4,096,000 |
| QSXGA | 2560×2048 | 5:4 | 5,242,880 |
| WQSXGA | 3200×2048 | 25:16 | 6,553,600 |
| QUXGA | 3200×2400 | 4:3 | 7,680,000 |
| WQUXGA | 3840×2400 | 16:10 | 9,216,000 |
| HSXGA | 5120×4096 | 5:4 | 20,971,520 |
| WHSXGA | 6400×4096 | 25:16 | 26,214,400 |
| HUXGA | 6400×4800 | 4:3 | 30,720,000 |
| WHUXGA | 7680×4800 | 16:10 | 36,864,000 |
Television/Movies
| Analogue TV Standard | Resolution | Display Aspect Ratio | Pixels |
|---|---|---|---|
| PAL (and SECAM) | ~350 X 576 lines | 4:3 | ~201600 |
| PalPlus | ~350 X 576 lines | 16:9 | ~201600 |
| Undecoded PalPlus | ~350 X 432 lines | 16:9 | ~151200 |
| NTSC | ~270 X 480 lines | 4:3 | ~129600 |
| Laserdisc | ~560×576(480 for NTSC) | 4:3 | ~322560 (268800 for NTSC) |
| VCR | ~240×576(480 for NTSC) | 4:3 | ~138240 (115200 for NTSC) |
| S-VHS | ~400×576(480 for NTSC) | 4:3 | ~230400 (192000 for NTSC) |
| Digital Standard | Resolution | Display Aspect Ratio | Pixels |
|---|---|---|---|
| Video CD | 352×288(240 for NTSC) | 4:3 (non-square pixels) | 101376 (84480 for NTSC) |
| China Video Disc | 352×576(480 for NTSC) | 4:3 (non-square pixels) | 202725 (168960 for NTSC) |
| SVCD | 480×576(480 for NTSC) | 4:3 (non-square pixels) | 276480 (230400 for NTSC) |
| EDTV 480p | 640×480, 704×480 or 852×480 | 4:3 or 16:9 | 307200, 337920, 408960 |
| DVD | 704×576(480 for NTSC) | 4:3 or 16:9 (non-square pixels) | 405504 (337920 for NTSC) |
| D-1 | 720×576(480 for NTSC) | 4:3 or 16:9 (non-square pixels) | 414720 (345600 for NTSC) |
| D-1 NTSC (square pixels) | 720×540 | 4:3 | 388800 |
| HDTV 720p | 1280×720 | 16:9 | 921600 |
| HDTV 1080p | 1920×1080 | 16:9 | 2073600 |
| HDTV 1080i | 1920×1080 | 16:9 | 2073600 |
| Digital Film Standard | Resolution | Display Aspect Ratio | Pixels |
|---|---|---|---|
| Academy 4K | 3656×2664 | 1.37:1 | 9739584 |
| Digital cinema 4K | 4096×1714 or 3996×2160 | 2.39:1 or 1.85:1 | 7020544, 8631360 |
| Academy 2K | 1828×1332 | 1.37:1 | 2434896 |
| Digital cinema 2K | 2048×858 or 1998×1080 | 2.39:1 or 1.85:1 | 1757184, 2157840 |
See also
External links
- [Screen size measures]
- [Online screen size calculator]
- [Display the resolution and color bit depth of your current monitor.]
- [How Many Dots Has It Got?]
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