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

Positioning Techniques, Explain Positioning Techniques in computer Graphics...

Explain Positioning Techniques in computer Graphics in detail

What do you understand by the term contone, Question : (a) What do you...

Question : (a) What do you understand by the term ‘contone'? (b) What are spot colours? (c) You have been asked to prepare an artwork (a magazine) to send to a printer.

Briefly explain how you could create the gun barrel effect, Question 1: ...

Question 1: (a) Describe what you understand by Rotoscoping in Graphic effects. Give details how Rotoscoping could be achieved in After Effects CS3. (b) Using one algorithm

Reflection, What is the advantages and disadvantages of reflection ?

What is the advantages and disadvantages of reflection ?

Important points about the diffuse reflection, Important Points About the D...

Important Points About the Diffuse Reflection An extremely rough surface appears uniformly bright from each viewing direction Q the intensity of reflected light is identical i

What is a dot size and interdot distance, What is a dot size and interdot d...

What is a dot size and interdot distance? Dot size may be explained as the diameter of a single dot on the devices output. Dot size is also known as the Spot size.  Interdo

Write a c code for generating concentric circles, Write a C code for genera...

Write a C code for generating concentric circles.  Put the circle function circleMidpoint()in a for loop  as follows: for( int radius = MinRadius; radius circleMidpoint(i

Advantages of jpeg images, Advantages of JPEG Images Huge compressi...

Advantages of JPEG Images Huge compression ratios mean sooner download speeds. JPEG produces outstanding results for main photographs and complicated images. JPEG s

Rotation - 2-d and 3-d transformations, Rotation - 2-D and 3-D transformati...

Rotation - 2-D and 3-D transformations Within 2-D rotation, an object is rotated via an angle θ along w.r.t. the origin. This angle is assumed to be +ive for anticlockwise rot

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