Image encoding for faster decoding

Abstract

Image data to be processed multiple times for display is encoded to provide faster display processing. For example, an original image having pixels that may be either transparent or non-transparent may be displayed multiple times within a single display and/or over successive displays. Rather than having to determine pixel transparency on a pixel-by-pixel basis each and every time the image is to be processed for display, the original image is encoded to generate an encoded image. The encoding process involves grouping the original image pixels into sets and characterizing the transparencies of the pixels of each set. A code signal representing the results of the characterization of each set of pixels is then encoded into the encoded image, along with the original image pixels. Each time the original image data is to be processed for display, the encoded image rather than the original image is used as input to special transparency decode processing. During decode processing, the code signals are retrieved from the encoded image and used to determine how to display the corresponding sets of pixels which are also retrieved from the encoded image. In this way, the original image data can be processed for display multiple times without having to perform pixel transparency analysis, one pixel at a time, each time the image is displayed.