Browse Prior Art Database

Method for Fast Rendering of Transparent Images

IP.com Disclosure Number: IPCOM000005603D
Original Publication Date: 2001-Oct-18
Included in the Prior Art Database: 2001-Oct-18
Document File: 4 page(s) / 750K

Publishing Venue

Motorola

Related People

Mark A. Patel: AUTHOR

Abstract

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.

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Method for Fast Rendering of Transparent Images

Mark A. Patel

ABSTRACT

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.

THE PROBLEM

In the field of computer graphics, transparent images are widely used in a variety of applications such as web pages and games.  Their nature allows a non-rectangular entity to be rendered in front of an arbitrary background, thus allowing objects to apparently to ‘float’ on top of the background. 

The traditional approach to rendering transparent images is to scan each and every pixel in the image: opaque pixels are rendered, transparent pixels are not.  While very simple, this process must be applied to every pixel each time the image is rendered, thereby requiring significant processing power to achieve acceptable rendering speeds.

Devices such as wireless phones have limited processing power and may not be capable of rendering transparent images at a sufficiently fast rate, thereby making their use impractical.  These devices are typically very sensitive to increases in size, weight, product cost and power consumption; thus, the use of a faster processor or dedicated graphics acceleration hardware is generally not an attractive solution.

THE SOLUTION

In a typical transparent image, opaque and transparent pixels are not randomly distributed throughout the image; rather, they tend to occur in contiguous groups.  For example, consider the image in figure 1.  This image of a lit bomb includes contiguous groups of transparent pixels at the top of the image and along its sides....