Aliasing in computer graphics pdf

In this antialiasing method pixel intensity is determined by calculating the areas of overlap of each pixel with the objects to be displayed. Antialiasing by computing area is referred to as Area sampling or Prefiltering. A modification to Bresenham's algorithm was developed by Pitteway and Watkinson. In this algorithm, each pixel is given intensity depending on the area of overlap of the pixel and the line.

So, due to the blurring effect along the line edges, the effect of anti-aliasing is not very prominent, although it still exists. For sampling shapes other than polygons, this can be very computationally intensive.

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Elizabeth Howell. Anti- aliasing computer graphics 1. What Does Aliasing Means? In computer graphics, the process by which smooth curves and other lines become jagged because the resolution of the graphics device or file is not high enough to represent a smooth curve. Smoothing and antialiasing techniques can reduce the effect of aliasing. Anti-Aliasing Anti-aliasing is a technique used in digital imaging to reduce the visual defects that occur when high-resolution images are presented in a lower resolution output devices like the monitor or printer.

Aliasing manifests itself as jagged or stair-stepped lines Also known as jaggiest on edges and objects that should otherwise be smooth. With sound, aliases are removed by eliminating frequencies above half the sampling frequencies. Before and After of Anti-Aliasing Anti-aliased polygons smoothed edges Anti-aliased polygons smoothed edges 5. What Does Anti-aliasing Do?

Anti-aliasing makes these curved or slanting lines smooth again by adding a slight discoloration to the edges of the line or object, causing the jagged edges to blur and melt together. It also removes jagged edges by adding subtle color changes around the lines If the image is zoomed out a bit, the human eye can no longer notice the slight discoloration that antialiasing creates.

Do We really need Anti-aliasing? Jaggies appear when an output device does not have a high enough resolution to represent a smooth line correctly. The pixels that make up the screen of the monitor are all shaped in rectangles or squares. Because lighting up only half of one of these square pixels is not possible. The jagged line effect can be minimized by increasing the resolution of the monitor, making the pixels small enough that the human eye cannot distinguish them individually.

This is not a good solution, however, because images are displayed based on their resolution. A single image pixel may take up many monitor pixels, making it impossible for a higher resolution monitor to mask the jagged edges.

This is where anti-aliasing is required. Anti-Aliasing Techniques Anti-Aliasing techniques were developed to combat the effects of aliasing. This increases the cost of image production. Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. What's New. Most popular in GBlog. More related articles in GBlog.