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Method for Fast Rendering of Transparent Images Disclosure Number: IPCOM000005603D
Original Publication Date: 2001-Oct-18
Included in the Prior Art Database: 2001-Oct-18

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Mark A. Patel


Transparent images are pervasively used in graphical user interfaces, especially for game applications. Their nature allows a non-rectangular entity to be rendered in front of an arbitrary background, thus allowing objects to seemingly float on top of the background. However, devices with limited processing power may not be capable of rendering transparent images at a sufficiently fast rate, thereby making their use impractical. The traditional approach to rendering transparent images is to scan each and every pixel in the image: opaque pixels are rendered, transparent pixels are ignored. Though very simple, this process must be applied to every pixel each time the image is rendered, thereby limiting rendering speeds. In a typical transparent image, opaque and transparent pixels are not randomly distributed throughout the image; rather, they tend to occur in contiguous groups. By processing homogenous groups of pixels instead of individual pixels, the rendering process can be greatly expedited. The invention provides a method of expediting the rendering process by analyzing the image during loading and identifying the homogenous groups of pixels within the image. This information is then stored with the pixel data and subsequently used to simplify, and hence expedite, the rendering process.