tailieunhanh - Lecture Computer graphics: Lecture 4 - Fasih ur Rehman

LCD basically consists of a layer of liquid crystal, sandwiched between two polarizing plates. The polarizers are aligned perpendicular to each other (one vertical and the other horizontal), so that the light incident on the first polarizer will be blocked by the second. This is because a polarizer plate only passes photons (quanta of light) with their electric fields aligned parallel to the polarizing direction of that plate. | Computer Graphics Lecture 04 Fasih ur Rehman Last Class Overview of Graphics Systems Display Devices Colors and colored displays Raster displays and frame buffer Today’s Agenda Overview of Graphic Systems Vector Displays Movie Standards LCD’s Some Definitions A rectangular array of points or dots is called Raster. A Pixel is picture element of raster. A row of pixels is known as Scan Line. Picture elements stored in memory are called Frame Buffer. Pixel Scan Line Resolution The Resolution is defined as the number of dot per inch or centimeter that can be plotted horizontally & vertically. Higher the resolution, smaller the spot size. Resolution is related with quality of the graphics system. Higher the resolution, better the graphics system High quality resolution is 1280x1024 The intensity distribution of spots on the screen has Gaussian distribution. Adjacent points will appear distinct as long as their separation is greater than the diameter at which each spot has intensity of . | Computer Graphics Lecture 04 Fasih ur Rehman Last Class Overview of Graphics Systems Display Devices Colors and colored displays Raster displays and frame buffer Today’s Agenda Overview of Graphic Systems Vector Displays Movie Standards LCD’s Some Definitions A rectangular array of points or dots is called Raster. A Pixel is picture element of raster. A row of pixels is known as Scan Line. Picture elements stored in memory are called Frame Buffer. Pixel Scan Line Resolution The Resolution is defined as the number of dot per inch or centimeter that can be plotted horizontally & vertically. Higher the resolution, smaller the spot size. Resolution is related with quality of the graphics system. Higher the resolution, better the graphics system High quality resolution is 1280x1024 The intensity distribution of spots on the screen has Gaussian distribution. Adjacent points will appear distinct as long as their separation is greater than the diameter at which each spot has intensity of about 60% of that at the center of the spot. Aspect Ratio The Aspect Ratio is the ratio between number of scan lines in a rater and the number of pixels in a scan line necessary to produce equal length lines in both directions on the screen. For example 1280 x 768 has an aspect ratio of 5:3. Vector Display The electron beam illuminates only the parts of the screen where a picture is to be drawn. Works like plotters . draws a one picture line at a time Used in line drawing and wireframe displays Picture definition is stored as a set of line-drawing commands stored in a refresh display file. Number of lines derive Refresh rate and refresh cycle is between 30 and 60 per second Can draw 100,000 short lines at this refresh rate Vector Displays Advantages Resolution is higher than raster Line drawings are smooth Vector displays are not suitable for realistic shaded scens Vector Display Movie Theaters Films play at 24 fps by . film projectors .