The LCD Buyer's Guide
Last updated: March 20th 2008
Welcome to The LCD Buyer’s Guide. The purpose of this thread is to aid those who are planning on purchasing an LCD monitor in the near future to make the smartest purchasing decision, as well as to inform readers about some of the main characteristics of this technology. This thread will attempt to accommodate the needs of serious gamers, video enthusiasts, digital artists, regular application users, as well as users just looking for simple display to just surf the net or benchmark. Additionally, if you find any mistakes in this thread or a collection of grammatical errors, PM me and I’ll see of I can make these changes whenever I have time. I would greatly appreciate it.
Glossary:
First let us begin by addressing a few terminologies that may aid in the comprehension of liquid crystal displays:
Key:
Simple Term (long forms / Alternatives) = Definition and useful explanations. Note: In occasions, “Note:” will be used to point out common misinterpretations.
Terminologies:
TFT(Thin Film Transistor) = The technology behind LCD’s, which is a kind of transistor where a layer of thin film particles in each pixel bend when provided voltage in order to cover light or isolating colors from the backlight.
LED(Light-Emitting Diode) = Is a semiconductor diode based technology that emits light in response to an electric current, also known as an electroluminescence (EL) effect.
LCD(Liquid Crystal Display) = A type of TFT based display, more commonly used as computer monitors and television displays.
OLED(Organic Light-Emitting Diode) = A type of LED based display with organic compounds, more commonly used with small devices like cell phones.
VGA(Video Graphic Array) = An analogue interface, more common with old computer monitors and video cards, as well as CRT monitors.
DVI(Digital Visual Interface) = A digital interface, used as a standard for newer flat panel computer monitors.
Pixel = The smallest element of an image that can be individually processed in a video display system (dictionary.com). Physically speaking, each pixel on a color flat panel displays is comprised of a red, green, and blue diode, in addition to a white diode for very high luminance displays.
Pixel Pitch = The linear measurement of a unit square of pixel area, most commonly measured with flat panel displays as the diagonally length of a single pixel (excluding spacing) in millimeters (mm). Smaller
Screen Resolution = The measurement of unit pixels, usually measured by height and length in the following format: LENGTH x HEIGHT. For example: 800x600. Note: A higher screen resolution does NOT mean less anti-aliasing is needed. In this case, a high resolution with a small screen size would indicate pixels with small pixel pitches packed closer together, thus making aliasing (“jaggies”) less noticeable.
Native Resolution = The maximum screen resolution in terms of the total physical pixel area. Due to flat panel’s static pixel nature, higher virtual resolutions are impossible, while lower virtual resolutions have to be resized by a computer integrated in the display that creates filler pixels for virtual resolutions that are not divisible by two with the native resolution.
Dead pixels(Stuck pixels) = Damaged pixels or pixels that do not responding adequately to the signal it is receiving. This problem is more common with low-grade LCD’s.
Backlight = The form of illumination used for LCD displays. Backlighting methods include Incandescent light, ELP (Electroluminescent Panel), CCFL (Cold Cathode Fluorescent Lamps), HCFL (Hot Cathode Fluorescent Lamps), and more recently LED’s. ELP’s are more common with smaller devices, because they give more uniform backlighting but require a high AC power source. Larger displays, like LCD monitors and televisions, more commonly use either one or many white CCFLs that cover most of the color spectrum. LED backlighting, although expensive at the moment, may become the standard backlighting method of the future because of its abilities to turn off and on very quickly during operation, thus giving very dark levels while increasing power and response time efficiency.
Backlight Bleeding = An effect caused when some backlighting leaks out from the sides of the screen, resulting in lighter colored edges than the rest of the screen's surface.
Contrast Ratio = The light intensity between black/dark levels and white/light levels. Higher contrast ratios usually equates to better black/dark levels.
Luminance = Simply put, it’s the brightness level on a LCD, measured in nits or candelas per square meter (cd/m2). 1 nit = 1 cd/m2.
Viewing Angles = The minimum degree of angle at which a screen can be viewed without losing image quality, measured by the angle of a perpendicular viewing cone who’s tip touches each pixel. Note: Many companies will measure the angle by how “acceptable” the image quality is instead of the minimum change in image quality.
Response Time = The average time it takes a pixel to change from one color to another, measured in milliseconds (ms). Note: Response time is different for many combinations of color and contrast transitions.
Delay Time = The average time it takes a monitor from the retrieval of a frame by the computer to its execution as an image on the screen.
Input Lag = The effect resulting from a high delay time.
Tr(Time Rise) = [Usually] the response time from 90% to 10% brightness. Sometimes measured from 100% ‘on’ to ‘off’.
Tf(Time Fall) = [Usually] the response time from 10% to 90% brightness. Sometimes measured from ‘off’ to 100% ‘on’.
TrTf(Time Rising & Time Falling) = Simply put, it’s the sum between Tf and Tr (not the average). For instance, 5ms Tr + 3ms Tf = 8ms TrTf.
GTG(Gray-To-Gray / Grey-To-Grey) = Pixel response time measurement from one grey scale to another, and vice versa. GTG transitions are usually slower than WTB transitions.
White/Black(White-To-Black / WTB) = Pixel response time measurement from fully black to fully white, and vice versa. WTB transitions are usually faster than GTG transitions.
Motion Blur = An effect caused when pixel delay is enough with dynamic images that the image appears to be blurred. Note: Motion blur is a step below ghosting.
Ghosting: = An effect caused when pixel delay is enough with dynamic images that the image appears to have fading antecedents. Note: Ghosting is a step further from motion blur.
Mura Effect = An effect caused by an imperfection in the screen's homogeneity, and could be due to a factory error in the sealing process (more common with low grade LCD’s) or when too much pressure is applied on the screen. For illustrations or more information, go to: http://www.behardware.com/articles/5...ad-pixels.html
Color Banding = An effect caused by inaccurate color representation of the color scale, which results in the appearance of more monochromatic ‘bands’ of color in a smooth color gradient. For instance: http://upload.wikimedia.org/wikipedi..._example01.png
Bezel = A term for the plastic or metal frame/cover surrounding the actual display panel.
VESA(Video Electronics Standards Association) = A standardization organization for many aspects of a computer display like connectors, mounting system, power consumption, quality standards, etc. Their site: www.vesa.org/
Computer Display Resolutions:
Key:
Computer Display Standards = Resolution (Aspect Ratio)
Computer Displays:
MDA = 720x350 (72:35)
CGA = 160x200 (4:5), 320x200 (16:10), 640x200 (16:5)
Hercules = 720x348 (60:29)
Professional Graphics Controller = 640x480 (4:3)
MCGA = 320x200 (16:10), 640x480 (4:3)
8514 = 1024x768 (4:3)
VGA = 320x200 (16:10), 640x350 (64:35), 640x480 (4:3), 720x400 (9:5)
SVGA = 800x600 (4:3)
XGA = 640x480 (4:3), 1024x768 (4:3)
QVGA = 320x240 (4:3)
SXGA = 1280x1024 (5:4)
UXGA = 1600x1200 (4:3)
WUXGA = 1920x1200 (16:10)
WXGA = 1280x720 (16:9)
WSXGA / WXGA+ = 1440x900 (16:10)
Television Display Resolutions:
Note: Some TV res. are the same as some PC res.
Also note that Im not 100% sure about the true Interlaced common resolution :P
Key:
Television Display Standards = Resolution (Aspect Ratio)
Progressive Displays: (-p extension)
VGA 640x480
480p 720x480
576p - PAL Plus 720x576
720p 1280x720
1080p 1920x1080
Interlaced Displays: (-i extension)
Broadcast NTSC 440x330 (Stretched to VGA)
DV NTSC 480i ~720x350 - ~720x400
DV-PAL-576i 720x405
HDV & Broadcast 1080i 1440x810 (Stretched to 1080p)
Common Aspect Ratios:
5:4 = 640x512, 720x576, 1280x1024, 1800x1440, 2560x2048, etc.
4:3 = 320x240, 480x360, 640x480, 800x600, 832x624, 1024x768, 1152x864, 1280x960, 1400x1050, 1600x1200, 1920x1440
16:10 = 320x200, 1440x900, 1680x1050, 1920x1200, 2560x1600, 3840x2400, 7680x4800, etc.
16:9 = 1280x720, 1600x900, 1920x1080, etc.
5:4 and 4:3 aspect ratios were more common with CRT’s and the early LCD’s. As applications started migrating to a widescreen format, newer flat panels started supporting wide screen as well. HDTV’s are commonly based on a 16:9 aspect ratio, while wide screen computer monitors use 16:10 aspect ratios.
Here is a comparison between 4:3 and 16:9 in Counter Strike: Source:
Source: http://www.halflife2.net/forums/showthread.php?t=49242
Computer Interfaces:
VGA
Supposedly VGA connectors can be modified from a PC to an HDTV without having to buy an expensive VGA to Component converter. I haven’t tried it myself, but it seems plausible considering that VGA connectors are simply analog RGB output cable like Component cables. For more info, scroll down to the “Links:” section under “Info / News:”. This would be useful for setting up Home Theater boxes. If anyone has tried this successfully, PM me so I can add a subsection about the actual mod.
Standard Cable:
Pin Arrangement:
DVI
DVI can support up to UXGA, WUXGA and HDTV resolutions or a signal over 160MHz with a single cable. Higher frequencies and resolutions can be achieved with a dual set of links (Commonly seen with 30” QXGA or WQXGA displays) or multiple links if needed. Here are some more details about the DVI interface for any interested modders that want to experiment
Standard Cable:
Connector Types:
Pin Arrangement:
LCD’s vs. CRT’s
Here are a few comparisons that may aid in your decision between LCD's and CRT's:
Contrast Levels:
Any decent CRT will have much better contrast levels than a high-end LCD. LED backlighting could considerably improve LCD contrast ratio in the future, but the costs of such technology at the moment is very high relative to a regular CRT monitor with similar quality.
Delay Time:
LCD’s have higher input lags than CRT’s, but they are both virtually unnoticeable to humans. (See Response Time below for more info.)
Response Time:
CRT’s are much more responsive, with response times under 1ms. LCD technology however is becoming faster as time progresses, and it is said that anything under 8ms response time would be unnoticeable to humans. Though, in professional gaming it helps to reduce the sum of delays caused by computer input and output, and human of input and output. In the case of professional gaming, considering the input lag and response times of LCD technology, a CRT user could have a slight competitive advantage compared to a LCD user. In this case, a CRT would be a wiser choice.
Input Lag - Animated Wiki GIF Version:
Input Lag - YouTube Video Version:
http://www.youtube.com/watch?v=pi2OE6hSh00
Credits to adamsleath for the find.
Monitor Frequencies:
Despite most LCD’s have a low frequency of 60Hz, LCD’s do not flicker because all the pixels on a LCD refresh individually. On the other hand, a CRT has to constantly refresh the entire image with 3 electron beams of colors red, green, and blue. Although CRT’s under high frequencies may not seem to flicker, for some people it causes headaches to watch a CRT for long periods of times.
Color Depth:
CRT’s have a wider spectrum of colors, accurately representing 32-bit color (about 4.3 billion distinct colors) and theoretically capable of representing even more. At the moment, LCD’s can at most replicate Truecolor (24-bit or 16.8 million distinct colors), which is also dampened by cases where color banding is present or where color depth has to be sacrificed to 16.2 million distinct colors in favor of response time.
Focus & Geometry:
LCD’s are made up of millions of small colored pixels equally distributed throughout a flat surface, so the image looks equally well on the entire screen. On the other hand, CRT’s use an electron beam that projects over a curved lens. Newer CRT’s have a refractive lens that attempts to flatten the image, but this affects the sharpness of the picture the farther you view the image from the center of the screen. Because of this, widescreen CRT’s are not as common, since the difference the sharpness between the vertical extremes would be clearly differentiable from the (less sharp) horizontal extremes. Although, uneven backlighting and backlight bleeding is also a common problem with many LCD's, which in turn translates into uneven geometry. One of the objective when looking for LCD's is to simply find reviews that show LCD's that lack these defects if geometry is a big concern, and even so one could have the bad luck of getting a LCD with uneven backlighting or backlight bleeding. In this case, make sure the LCD has a warranty that will protect you against such defects so you can RMA it latter in case it shows up.
Sharpness & Resolution:
A high quality LCD’s is sharper per pixel at native resolution than a high quality CRT at its optimal resolution, because of the asymmetry that exists between the lens and the tube in a CRT monitor. With CRT’s a higher resolution usually results in a less sharp picture, while with LCD’s a lower resolution seems to result in a less sharp image. LCD’s are more restricted then CRT’s in terms of resolution scaling, because the differences between a native resolution and a non-native resolution tend to be so severe that it is best to always run the LCD at its native resolution. This is an important fact to consider if you’re intending to play games, since a higher resolution would require a better system to run the game smooth at native resolution, otherwise the higher video fidelity you were planning to achieve from a larger screen would be pointless. A screen from the same size, but with a larger pixel pitch (and lower resolution) would have a higher image quality. Thus, if you can not afford to run your most played game at high resolution, I would recommend sticking with a lower resolution screen with a small pixel pitch.
Durability:
the only part on a LCD that ages is the backlight. LCD’s commonly have a backlight that has a half-life of about 50,000 hours, resulting simply in a lower brightness level. If the backlight dies on a LCD, it is possible to replace it through the warranty. Apart from the backlighting, there is a chance of getting dead pixels. On the other hand, CRT’s ages in two ways: an oxide layer forms on the cathode of the electron gun, decreasing beam current, while at the same time the phosphor in the electron tube also ages and becomes less efficient. Most CRT’s half-life is about 10,000 to 20,000 hours. After each half-life, CRT’s lose both brightness and image quality.
Power consumption:
The power required to run an average LCD is about 1/3 the power needed to run an average CRT, and even less power is needed to run other flat panels like LED LCD’s and OLED displays. Less energy consumption in turn results in less heat dissipation as well.
Size, Portability & Ergonomics:
In terms of size, LCD’s are much smaller then CRT’s from all angles, but more noticeably in depth. In addition to size, LCD’s are much lighter as well, thus making them much more portable, although this is not to say that large flat panel displays are not heavy, they are just less heavy then their CRT counterpart. Ergonomically, some LCD’s are also sold quite stylishly with some companies using very discrete wall-mountable bezels, while others with elaborate glass or metal bezels. Most CRT’s, as new as they may be, they always seem to resemble old CRT’s from the early 90’s with cheap plastic bezels and glass screens. LCD panels usually come in two flavors: in glass/glossy screens, or in matte screens. Glossy screens usually give a sharper and darker image than the same panel with a matte screen, but matte screens are not as reflective. For dark, closed environments the glossy screens may make more sense; otherwise I would recommend a matte screen considering how annoying the reflectiveness becomes at times.
Marketing:
Whenever purchasing a monitors (or anything in general), one has to be aware of the marketing tricks companies use to beautify their products. With LCD’s often companies are not accurate about their response time ratings. At times when the average is expected, they publish the minimum time they achieved. In other instances, companies don’t give enough response time information. Another common marketing strategies company’s do is to claim colors that they actually can’t produce. The common marketing scheme seems to be to focus on the weaknesses the technology lacks to make it stand out from the comp
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