Raster and Random Scan display in Computer Graphics
What is a Raster Scan Display?
- A raster-scan display is a type of electronic display system that uses a rasterization process to create images.
- It involves the systematic scanning of the display area in a grid-like pattern, known as a raster, where each unit of the grid corresponds to a pixel.
- This method is widely used in cathode-ray tube (CRT) monitors and other display technologies.
Advantages of Raster Scan
- Simplicity: Raster scan displays are relatively simple in design, making them cost-effective and easy to manufacture.
- Compatibility: They are compatible with various types of display content, including text, graphics, and video.
- Widespread Adoption: Raster scan technology has been widely adopted and remains a common method for displaying visual information on screens.
Limitations of Raster Scan
Flicker
At lower refresh rates, flicker can occur, causing discomfort to viewers. Higher refresh rates mitigate this issue.
Resolution Constraints
The resolution of a raster scan display is limited by the number of pixels in the frame buffer.
Higher resolutions may require more sophisticated technologies.
Geometry Distortion
Cathode-ray tube (CRT) displays may suffer from geometric distortions, such as pincushion or barrel distortion, which can affect the accuracy of displayed images.
Random Scan Display
- A random scan display, also known as a vector display, is a type of electronic display system that differs from the traditional raster scan display.
- Instead of scanning the entire screen systematically in a grid-like pattern, a random scan display directly draws lines and shapes based on mathematical equations or specified coordinates.
- This approach is particularly useful for rendering vector graphics.
Advantages of Random Scan
Scalability
Graphics can be easily scaled without loss of quality, making random scan displays suitable for applications requiring variable graphic sizes.
Efficiency in Vector Graphics
The display excels at rendering vector graphics with a focus on lines, shapes, and curves.
Real-Time Interactivity
Random scan displays are well-suited for real-time interactive graphics, making them suitable for applications that require dynamic and responsive visual feedback.
Limitations of Random Scan
Pixel-Based Graphics
While excellent for vector graphics, random scan displays may not be as efficient when rendering pixel-based graphics or images.
Complexity in Pixel Rendering
Rendering detailed images with fine pixel-level control can be more challenging on random scan displays compared to raster scan displays.
Historical Context
Random scan displays were more prevalent in the early days of computer graphics, and while they offer unique advantages, raster scan displays have become more dominant in modern computing.
Conclusion
Random scan excels in precise vector graphics with real-time interactivity, while raster scan dominates modern computing.