Raster-Scan Systems
A Raster-Scan System is a method of displaying images on a screen by scanning them line by line from top to bottom. This is the most common technique used in CRT (Cathode Ray Tube) monitors, modern LCD/LED screens, and most televisions. In this system, the display is made up of pixels arranged in a rectangular grid, and the image is generated by controlling the intensity and colour of each pixel.
How Raster-Scan Systems Work
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Pixel Grid Formation – The display area is divided into a matrix of pixels (picture elements).
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Horizontal Scanning – An electron beam moves left to right across each line of pixels, lighting them up according to the stored image data.
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Vertical Scanning – After completing a line, the beam moves to the next line below until the entire screen is scanned.
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Frame Refresh – The process repeats rapidly (usually 60–120 times per second), creating a stable and flicker-free image.
Components of a Raster-Scan System
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Frame Buffer – Stores pixel data for the entire screen.
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Video Controller – Reads the frame buffer and generates signals to control the display.
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Display Device – CRT, LCD, LED, or other pixel-based output screens.
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Digital-to-Analog Converter (DAC) – Converts digital pixel data into analog signals for display (in older systems).
Advantages of Raster-Scan Systems
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Supports complex and realistic images with a wide range of colours.
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Easy to display photographs and shaded graphics.
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Compatible with modern graphics and multimedia applications.
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Supports animation and smooth motion with higher refresh rates.
Applications of Raster-Scan Technology
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Television broadcasting
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Computer monitors
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Gaming consoles
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Digital signage
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Multimedia presentations