JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III COMPUTER GRAPHICS Previous Question Paper (September - 2021 - R16)

The operating characteristics for the specified display technologies are as follows:

• Raster Refresh Systems: These systems store the image definition in a frame buffer as a set of intensity values for pixel positions. The electron beam sweeps across the screen row by row (scan lines) to refresh the display at a typical rate of 60 to 120 frames per second. It is suitable for displaying complex shaded scenes and solid areas.
• Vector Refresh Systems: Also known as random-scan displays, these systems draw an image by directing the electron beam only along the paths of the lines to be displayed. The display processor cycles through a display list of commands to redraw the lines repeatedly. It provides high resolution for line drawings but cannot easily display complex filled-in scenes.
• Plasma Panels: These are emissive displays that use a grid of conductors with a neon-based gas mixture sealed between glass plates. A voltage applied to intersecting conductors causes the gas to ionize and glow at that pixel location. They provide a stable, flicker-free image and are generally thin, though they have lower resolution compared to modern LCDs.
• LCDs (Liquid Crystal Displays): These are non-emissive devices that control light transmission by applying varying voltages to liquid crystal cells. The crystals rotate polarized light to either block or pass light from a backlight source. They are characterized by low power consumption, compact size, and are the standard for modern flat-panel displays.

The midpoint ellipse algorithm can be parallelized by partitioning the ellipse path into multiple segments and assigning each segment to a different processor. The procedure is as follows:

1. Domain Decomposition: Divide the total angular range of the ellipse (0 to 2π) into N equal segments, where N is the number of available processors.
2. Parameter Calculation: Each processor calculates the starting coordinates (x, y) for its assigned angular segment using the parametric equations:
   x = x₀ + rₓ cos(θ)
   y = y₀ + rᵧ sin(θ)
3. Local Execution: Each processor independently executes the standard midpoint ellipse algorithm for its specific segment. Since the algorithm is incremental, each processor uses the local decision parameter to determine the next pixel position within its assigned arc.
4. Synchronization and Merging: Once all processors complete their pixel calculations, the results are merged into the frame buffer. Because the ellipse is a continuous closed curve, ensure that boundary pixels between segments are handled to avoid gaps or overlaps.