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Scan Conversion Definition in Computer Graphics

Computer Graphics | Scan Conversion Definition: In this tutorial, we are going to learn about the Scan Conversion Definition, its implementation, methods of implementation, etc. By Monika Sharma Last updated : April 05, 2024

Scan Conversion Definition

The process of representing continuous graphics object as a collection of discrete pixels is known as scan conversion.

This can be demonstrated by a line that is defined by its two endpoints and the equation of that line. Also, by a circle that is represented by its mid-point and the radius.

The job of conversion of every primitive object represented on the graphics screen into a set of pixels that is its basic form is termed as scan conversion or rasterization. The conversion of the graphic screen lines and objects depicted in pixels is scan conversion.
Thus, the process of scan conversion requires some basic rules and guidelines to be followed,

• All the objects drawn on the graphics screen should be of uniform brightness. The brightness content must be the same for every point so that the conversion is made easy.
• The objects drawn on the graphics screen should be free from any orientation and independent of length and size.

Image source: https://www.docsity.com/en/scan-conversion-introduction-to-computer-graphics-lecture-slides/313686/

Pixels

A pixel is the smallest unit of a graphics image or referred to as a physical point in a raster. This is the component of the original graphics image which provides even more clear representation than the original image.

The intensity of each pixel may vary as it depends on the image represented in the graphics image and the color combination is represented by the three basic colors that are red, green and blue.

Scan Conversion Methods

Scan conversion is done using two methods or techniques,

1. Analog methods: This conversion is done for large numbers of delay cells and is appropriate for an analog video. It may be performed also using a particular specialized scan converter vacuum tube. In this case, all polar coordinates i.e. (Angle and distance) data from a source such as a radar receiver, so that it can be displayed on any raster scan display.
2. Digital methods: In this particular method, any picture is stored in a line or frame buffer with n1 speed (data rate) and is read with n2 speed, several picture processing techniques are applicable when the picture is stored in buffer memory including kinds of interpolation from simple to smart high order comparisons, motion detection and to improve the picture quality and prevent the conversion complications.

Need of Scan Conversion Algorithms

This helps in accelerating the process of scan conversion and can generate graphic objects at a faster rate comparatively. Using these algorithms memory is also used efficiently and the production quality of the objects on the screen is also improved.

We can use a random scan system for this process. It uses a beam of electrons that are accelerated through the potential difference and operates like a pencil on the screen of the cathode ray tube thus producing objects on the screen. These are constructed through a particular sequence of lines drawn.

The Scan Converting rate is a technique that is used in video processing. In this technique, we can change the horizontal and vertical frequencies for different purposes.

We can apply the scan conversion algorithm for various objects that are,

• Point
• Line
• Polygon example rectangle, triangle and many more
• Circle
• Arc
• Sector
• Any filled region

Advantages of Scan Conversion

• This scan conversion methodology is used for many purposes including TV, the card used to capture a video, LCD monitor, projectors used for video display any more.
• This conversion technique has large and many applications in daily life.
• One can efficiently perform this scan conversion using high and good speed circuits that are integrated.

Disadvantages of Scan Conversion

• While digital scan conversion, the analog video signal gets converted into digital signals of data.
• We can apply scan conversion with only LSI (Large Scale Integration) and VLSI (Very Large Scale Integration) integrated circuits.