Liberate Technologies, Inc.

David Mott

James Helman

Chee Yu

The invention provides an improved method and system for presenting television signals, including anti-aliasing of text with respect to a background. The background color is determined relatively locally for each element to be anti-aliased, and text or other graphics overlaid on that background are anti-aliased with respect to each relatively local background color. Also, anti-aliasing can be applied to blur text and graphics more vertically than horizontally to reduce flicker, and to blur chrominance more than luminance to reduce cross-chrominance artifacts resulting from Y/C separation. Similar techniques may be used for filtering images in addition to anti-aliasing text characters.

Anti-aliasing television signals for display

The invention provides an improved method and system for presenting color television signals. Television signal chrominance values for foreground elements are adjusted in response to television signal chrominance values for background elements, so as to minimize display artifacts while preserving the relative color contrast between foreground and background. (1) The invention modifies I and Q values of the foreground color to reduce the difference of the foreground I and Q with respect to the background I and Q. (2) The invention modifies Y, I and Q values of the foreground color to avoid colors known to display poorly for selected output devices. (3) The invention modifies Y values of the foreground color to maintain intended visual contrast between foreground and background colors. (4) The invention modifies Y, I and Q values of the foreground color to decrease cross-luminance separation artifacts at the border between foreground and background colors.

Television signal chrominance adjustment

Displaying a hypermedia document such as an HTML web page on a television display without using horizontal scroll bars, while preserving the look and feel of the web page as originally contemplated by the web page designer. When possible, each web page is reduced to fit within a specified threshold such as the horizontal margins of the display. Any vertical portion of the web page overlapping the vertical margin is accessed through a vertical scroll bar or similar technique. In a first pass, web page reduction includes rendering the web page without any scaling or changes to the web page and recording web page content statistics to obtain a global indicator as to the horizontal size of the entire web page. Content statistics recorded in each cell includes the following cell content characteristics: the width of the largest non-breaking line of elements; the width of the largest element within a non-breaking line; and the width of the largest embeds or non-breaking horizontal sequence of embeds within a cell. If the total width of the cells is within the specified threshold, no further reduction routine is necessary; otherwise each cell width is reduced using a cell characteristic to help define the new width of each cell. After reduction, the total width of the reduced cells is again checked if it is within the specified threshold. If so, the horizontal size of the web page is within the specified threshold is thus, rendered for a second time using the chosen cell characteristic to help define the width of each cell. Otherwise, successive iterations of cell reduction using a different cell characteristic is performed until the total width of each reduced cell is less than the specified threshold or until the entire set of cell characteristics available is exhausted.

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Mountain View, CA, United States of America

David Mott