Crt - cathode ray tube, Computer Graphics

Assignment Help:

CRT - Cathode Ray Tube

  • Electron gun is used to send an electron beam aimed at a particular point on the screen. Deflection system is used to make the beam strike the screen on a precise point.
  • When electron beam strikes the screen, coated phosphor emits light due to the natural phenomenon called phosphorescence. Output decays rapidly approximately within 10 - to 60 microseconds.
  • As a result of this decay, the entire screen must be refreshed at least 30-60 times per second. This is called the refresh rate. If the refresh rate is low, screen will tend to flicker.
  • CFF (Critical Fusion Frequency) is the minimum refresh rate needed to avoid flicker. It depends on the persistence of the phosphors and the human vision system.
  • Electron beam traces out a path on the screen, hitting each pixel once per cycle. Tracing out of the entire picture once is called a cycle. In case of a raster scan display we call the horizontal path of the beam a scan line. In case of random scan display, the path is a directed set of line segment, which are called vector lines.
  • On a raster scan display, refresh rate is fixed as mentioned above. On a vector display, a scan is in the form of a list of directed line segments to be drawn, so the time to refresh is dependent on the length of the display list. For small and simple object displays, some kind of delay is introduced to avoid un-necessary refreshing of the screen.
  • In color CRT, shadow-mask method is most common since it produces a wide range of colors. In this method, each pixel consists of a group of three phosphor dots (one each for red, green, and blue), arranged in a triangular form called a triad. The shadow mask is a grid structure with one hole per pixel. To excite one pixel, three electron guns are used one for each of red, green, and blue. Each gun fires its electron stream through the hole in the mask to hit that pixel.

Related Discussions:- Crt - cathode ray tube

Transformation for 3-d scaling, As we already seen that the scaling proces...

As we already seen that the scaling process is mainly utilized to change the size of an object. The scale factors find out whether the scaling is a magnification as s>1 or a red

What is polygon mesh, What is Polygon mesh?  Polygon mesh is a method t...

What is Polygon mesh?  Polygon mesh is a method to show the polygon, when the object surfaces are tiled, it is more convenient to state the surface facets with a mesh function.

Video controller, Video controller : A Fixed area of the system memory co...

Video controller : A Fixed area of the system memory controller for the frame buffer, and the video controller is given direct access to the frame – buffer memory, frame – buffer

Types of refresh monitors - raster scan and random scan, Types of Refresh M...

Types of Refresh Monitors - Raster Scan and Random Scan There are two types of refresh monitors, i.e. the Raster Scan and Random Scan that will be illustrated separately.

Graphic interchange format (gif), Graphic Interchange Format (GIF): The Gr...

Graphic Interchange Format (GIF): The Graphic Interchange Format is an efficient implies to transmit images across data networks. In the early 1990 year the original designers of

Discuss in detail about rendering, Discuss in detail about rendering Co...

Discuss in detail about rendering Computer animation uses a technique termed as avars (animation variable) where starting point is generally a series of stick figures; for exam

Remark for the bresenham line generation algorithm, Remark for the Bresenha...

Remark for the Bresenham Line Generation Algorithm Remark: The algorithm will be properly the same if we suppose | m | Algorithm | m | (a) Input two line endi

Interpolation of surface - polygon rendering, Interpolation of surface - Po...

Interpolation of surface - Polygon Rendering Interpolation of surface normals beside the polygonedge between two vertices is demonstrated above in the figure 15. Here the norm

Calculate the gray level value for all the pixels, An 8x8 image f[i,j] has ...

An 8x8 image f[i,j] has gray levels given by the following equation: f [i , j]= ? i-j ? ; i,j=0,1,2,3,4,5,6,7. a. Calculate the gray level value for all the pixels in the 8x8

Briefly explain the term density range, QUESTION a) Explain with the he...

QUESTION a) Explain with the help of a diagram, how a thermal inkjet printer works. b) Briefly explain the term density range. c) Distinguish between scaling and resampli

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd