Method and apparatus for displaying anti-aliased text

Abstract

The present invention provides a method and apparatus for displaying anti-aliased text. Text on a computer display device typically contains 'jaggy' edges (referred to as aliased text). The method of the present invention smoothes such 'jaggy' edges by blending the edges of text into the color background the text is being rendered on. A mask or alpha channel is created through which the text is rendered. The mask is created by drawing the text at a larger size (typically 4 times the size) and shrinking the image down or by using an outline vector extraction method. The mask is used to blend a bitmap representation of the text into the background. The present invention utilizes run-length compression to encode the alpha channel data. Additionally, to avoid the need for an original bitmap, the present invention encodes the text color information into the mask data, creating a unique bitmap/mask hybrid. Due to the creation and storage of a hybrid bitmap/mask, the memory requirements are significantly decreased. Further, when rendering the text, the run length compression provides the ability to ignore/skip multiple pixels. Consequently, the run length compression provides the ability to avoid blending or mixing the background image with the source color for multiple pixels.