Display Technology

Display TechnologyZKE 324Dr Fatanah SuhaimiDISPLAYSPixel picture elementSize: diagonal length of screenResolution (pixels on screen)VGA: 480 x 640SVGA: 600 x 800768 x 10241280 x 1024Picture size calculationResolution x bits required to represent number of colors in pictureExample: 16 color image, 100 pixels by 50 pixels16 = 4 bits4 bits x 100 x 50 = 20,000 bits

2PIXELSA Pixel is a picture elementA single point in a graphic imageA graphic display is divided into thousands or millions of pixels arranged in rows and columnsThe pixels are so close together, they appear connectedThe number of bits used to represent each pixel determines how many colours or shades of grey can be representedFor a B&W (black and white) monitor, each pixel is represented by 1 bitWith 8 bits per pixel, a monitor can display 256 shades or grey or 256 colours (28 = 256)

3DISPLAY SIZEUsually specified in inches and measured diagonallyValue cited is the diagonal dimension of the raster -- the viewable area of the displayE.g., a 15 monitor: (viewable image size, v.i.s. = ?? 13.6? )

1545DISPLAY SIZE

The diagonal, usually measured in inches. The diagonal measurement of a display as the actual viewable area is also dependent on the aspect ratio of the display. For a display device of the same area, the diagonal achieves a larger value in a widescreen than compared to a more square screen. There is a risk of manufacturers making displays wider than what is actually most convenient in order to make the diagonal achieve a larger value.

Main measurements are:Width and height Total area

6LCD SCREEN SIZES

http://en.wikipedia.org/wiki/Display_size7

DISPLAY RESOLUTIONResolution is the number of pixels on a screen displayUsually cited as n by mn is the number of pixels across the screenm is the number of pixels down the screenTypical resolutions range from640 by 480 (low end), to1,600 by 1,200 (high end)

8VIDEO RAM REQUIREMENTSTotal number of pixels is n mExamples640 480 = 307,200 pixels1,600 1,200 = 1,920,000 pixelsVideo RAM required equals total number of pixels times the number of bits/pixelExamples640 480 8 = 2,457,600 bits = 307,200 bytes = 300 Kbytes1,600 1,200 24 = 46,080,000 bits = 5,760,000 bytes = 5,625 Kbytes = 5.49 Mbytes

9VIDEO RAM (KB) PER IMAGE

10ASPECT RATIOAspect ratio is the ratio of the width to height of a display screen4:3 on most PCs16:9 on high definition displaysFor a 640 by 480 display, the aspect ratio is 640:480, or 4:3Related termsLandscapeThe width is greater than the heightPortraitThe height is greater than the width

11DOT PITCHDot pitch is a measure of the diagonal distance between phosphor dots (pixels) on a display screenOne of the principal characteristics that determines the quality of a displayThe lower the number, the crisper the imageCited in mm (millimeters)Typical values range from 0.15 mm to 0.30 mmNoteDot pitch, as specified, is the capability of the display1213DOT PITCH IMAGE: EXAMPLEQ: What is the dot pitch of an image displayed on a 15 monitor with a resolution of 640 by 480?A:640480ZZ = (6402 + 4802)1/2 = 8001 mm = 0.039 inchDot pitch= 15 / 800 inches= 0.01875 inches= 0.01875 / 0.039 mm= 0.481 mmNotes:14DOT PITCH ILLUSTRATEDPixel0.481 mm15DOT PITCH IMAGE TABLEResolutionDisplay Size1415171921640 x 4800.450.480.540.61800 x 6000.360.380.440.541024 x 7680.280.340.380.421152 x 10240.230.250.280.320.351280 x 10240.220.230.300.331600 x 12000.190.220.240.27Note: Dot pitch figures in mm (millimeters)16DOT PITCH IMAGE TABLEResolutionDisplay Size1415171921640 x 4800.450.480.540.610.67800 x 6000.360.380.440.490.541024 x 7680.280.300.340.380.421152 x 10240.230.250.280.320.351280 x 10240.220.230.270.300.331600 x 12000.180.190.220.240.27Note: Dot pitch figures in mm (millimeters)17COLOUR AND DISPLAYSPixel colour is determined by intensity of 3 colours Red Green Blue or RGB4 bits per colour16 x 16 x 16 = 4096 colours24 bit color (True Colour)16.7 million coloursVideo memory requirements are significant.

18COLOUR DISPLAYSCRT displaysEach pixel is composed of three superimposed dots: red, green, and blueRGB displayThe three dots are created by three separate beamsIdeally, the three dots should converge at the same point, however, in practice there is a small amount of convergence error, and this makes the pixels appear fuzzyLCDsColour is created by filtering/blocking different frequencies of light