Computer Monitor Factors And Performance Measurements
Luminance – is photometric measure and represents luminous intensity per unit. It basically describes how much light is passed through or is emitted from particular area. It is measured in candela per square meter (cd/m2) and indicates how bright is the surface so in computer monitor industry it represents the brightness of the display screen and it vary from 50 to 300 candelas per square meter.
Aspect Ratio – represent ratio of horizontal to the vertical length of the image. In most cases have aspect ratio of 4:3 which is common video graphic aspect ratio, while widescreen monitors have image display aspect ratio of 16:9 that is universal ratio for high definition television. Cinema aspect ratio is 21:9 (or 2.33:1) that at the moment use just Philips and Vizio through 2560×1080 (2.37) and for now it is not yet standardized.
Viewable image size – is generally measured diagonally and represents surface area of the computer monitor that displays image. CRT monitors have viewable size about 1 inch smaller than the tube while in LCD and LED monitors it is measured from corner to corner and represent whole viewable area. Because of the different type of measuring of CRT and LCD displays, 17 inch LCD (LED) is equivalent for 19 inch CRT monitor.
Screen size and viewble screen size compared and explained
Display resolution – during 2002 common display resolution was 1024×768 and most of the internet sites and multimedia were redesigned from 800×600 to new, higher format. Many computer applications and video games use higher resolutions like UXGA (1600×1200), SXGA+ (1400×1050), WXGA (1280×720), WSXGA+ (1680×1050) and other. In 2010 multiple manufacturers started producing monitors with 2560×1440 resolution and from May 2011 maximum resolution for wireless computer monitor is 4096×2160.
Dot Pitch – is computer monitor specification that describes distance between sub pixels of the same color in millimeters. The smaller dot pitch distance is (larger number) the better as picture will appear sharper. It is also measured in dots per inch.
Refresh Rate – present number of times in a second that display is illuminated (draw data) and it is limited by monitor response time. 16 inch CRT monitors had refresh rate of 60-72Hz, larger monitors had 72Hz refresh rate or higher. It is a little bit different with LCD monitors and closes equivalent is frame rate which is in LCD soften locked at 60fps (frames per second).
Response Time – presents needed time that monitor takes to go from black to white and back to black again. It is measured in milliseconds and lower number means that monitor response is faster and therefore is better. Typical black-white-black response of LCD monitors is from 8 ms to 16 ms and 2 to 6ms for gray to gray transition.
Contrast Ratio – is defined as the ratio of luminance that display screen is capable of producing ranging from brightest white to darkest black. When purchasing it is better to purchase display with higher contrast ratio but since this measure is not standardized manufacturers tend to put fake numbers stating dynamic contrast ratio measures.