Flicker reduction and size adjustment for video controller with interlaced video output

An apparatus for generating an interlaced video display image from a source image stored as a plurality of horizontal scan lines of pixel data stored as pixel color addresses in a video memory, said apparatus comprising:

• a controller, coupled to said video memory, for selectively reading from said video memory a first pixel color address from a first horizontal scan line of said source image and a second pixel color address from a second horizontal scan line of said source image;
• a look up table, coupled to said video memory, for reading said first pixel color address and outputting first output pixel color data from said look up table at the first pixel color address and reading said second pixel color address and outputting second output pixel color data from said look up table at the second pixel color address;
• and
• weighting means, coupled to said look up table, for receiving said first output pixel color data and said second output pixel color data and outputting hybrid pixel color data as a weighted value of at least said first output pixel color data and said second output pixel color data;
• wherein said hybrid pixel color data forms pixel data for a plurality of horizontal scan lines of the interlaced video display image, said weighting means computes a weighted value of at least said first output pixel color data and said second output pixel color data according to at least one of a predetermined number of weighting schemes, each of said predetermined number of weighting schemes being applied to first and second output pixel color data from successive pairs of first and second horizontal scan lines, and said plurality of horizontal scan lines equals x horizontal scan lines divided into a plurality of groups of n horizontal scan lines, and
• said predetermined number of weighting schemes comprises n-1 weighting schemes applied to output pixel color data from successive pairs of first and second horizontal scan lines such that for each group of n horizontal scan lines of pixel color addresses read from said video memory, said weighting means outputs n-1 horizontal scan lines of hybrid pixel color data so as to vertically scale the source image by a ratio of n:n-1.

An apparatus for generating an interlaced video display image from a source image stored as a plurality of horizontal scan lines of pixel data stored as pixel color addresses in a video memory, said apparatus comprising:

• a controller, coupled to said video memory, for selectively reading from said video memory a first pixel color address from a first horizontal scan line of said source image and a second pixel color address from a second horizontal scan line of said source image;
• a look up table, coupled to said video memory, for reading said first pixel color address and outputting first output pixel color data from said look up table at the first pixel color address and reading said second pixel color address and outputting second output pixel color data from said look up table at the second pixel color address;
• weighting means, coupled to said look up table, for receiving said first output pixel color data and said second output pixel color data and outputting hybrid pixel color data as a weighted value of at least said first output pixel color data and said second output pixel color data;
• luminance value calculating means, for calculating luminance values for said first and second output pixel color data;
• luminance storage means, for storing at least one of said calculated luminance values;
• and
• luminance adjustment factor calculating means, coupled to said luminance value calculating means, said luminance storage means, and said weighting means, for calculating a luminance adjustment factor from calculated luminance values for said first and second output pixel color data and a previously stored luminance value for output pixel color data from a line adjacent to said first or second horizontal scan lines;
• wherein said weighting means further selectively generates said hybrid pixel color data as a weighted average of said first output pixel color data and said second output pixel color data and said luminance adjustment factor and said hybrid pixel color data forms pixel data for a plurality of horizontal scan lines of the interlaced video display image.

A method for generating an interlaced display image from a source image comprising a plurality of horizontal scan lines of pixel data stored as pixel color addresses in a memory, said method comprising the steps of:

• selectively retrieving from said memory a first pixel color address from a first horizontal scan line;
• selectively retrieving from said memory a second pixel color address from a second horizontal scan line;
• outputting from a look up table, first and second output pixel color data stored at corresponding first and second pixel color addresses in said look up table;
• weighting at least said first and second output pixel color data to produce hybrid pixel color data for a horizontal output line of said interlaced display image;
• storing said first output pixel color data in a first latch;
• storing said second output pixel color data in a second latch;
• transferring said first output pixel color data from said first latch to said weighting means;
• and
• transferring said second output pixel color data from said second latch to said weighting means,
• wherein said plurality of horizontal scan lines equals x horizontal scan lines divided into a plurality of groups of n horizontal scan lines, and
• said predetermined number of weighting schemes comprises n-1 weighting schemes applied to output pixel color data from successive pairs of first and second horizontal scan lines such that for each group of n horizontal scan lines of pixel color addresses read from said video memory, said weighting means outputs n-1 horizontal scan lines of hybrid pixel color data so as to vertically scale the source image by a ratio of n:n-1.

A method for generating an interlaced display image from a source image comprising a plurality of horizontal scan lines of pixel data stored as pixel color addresses in a memory, said method comprising the steps of:

• selectively retrieving from said memory a first pixel color address from a first horizontal scan line;
• selectively retrieving from said memory a second pixel color address from a second horizontal scan line;
• outputting from a look up table, first and second output pixel color data stored at corresponding first and second pixel color addresses in said look up table;
• weighting at least said first and second output pixel color data to produce hybrid pixel color data for a horizontal output line of said interlaced display image;
• calculating luminance values for said first and second output pixel color data;
• storing at least one of said calculated luminance values in a buffer;
• retrieving, from said buffer, a previously stored luminance value for output pixel color data from a line adjacent to said first or second horizontal scan lines;
• and
• calculating a luminance adjustment factor from the calculated luminance values for said first and second output pixel color data and the previously stored luminance value;
• wherein said step of weighting further comprises selectively weighting said first and second output pixel color data with said luminance adjustment factor to produce hybrid pixel color data for a horizontal output line of said interlaced display image.

A system for displaying an interlaced video display image, comprising:

• a processor for receiving or generating a non-interlaced source image data;
• a video memory, coupled to said processor, for storing said source image data as a plurality of horizontal scan lines of pixel data representing pixel color addresses;
• a controller, coupled to said video memory, for selectively reading from said video memory a first pixel color address from a first horizontal scan line of said source image and a second pixel color address from a second horizontal scan line of said source image;
• a look up table, coupled to said video memory, for reading said first pixel color address and outputting first output pixel color data from said look up table at the first pixel color address and reading said second pixel color address and outputting second output pixel color data from said look up table at the second pixel color address;
• weighting means, coupled to said look up table, for receiving said first output pixel color data and said second output pixel color data and outputting hybrid pixel color data as a weighted value of at least said first output pixel color data and said second output pixel color data;
• digital to analog converting means, coupled to said weighting means, for receiving said hybrid pixel color data and converting said hybrid pixel color data into an analog output video signal;
• interlaced display means, coupled to said digital to analog converting means, for displaying said analog output video signal as a field of an interlaced display image;
• first latch means, coupled to said look up table, for latching said first output pixel color data;
• and
• second latch means, coupled to said look up table, for latching said second output pixel color data.

A system for displaying an interlaced video display image, comprising:

• a processor for receiving or generating a non-interlaced source image data;
• a video memory, coupled to said processor, for storing said source image data as a plurality of horizontal scan lines of pixel data representing pixel color addresses;
• a controller, coupled to said video memory, for selectively reading from said video memory a first pixel color address from a first horizontal scan line of said source image and a second pixel color address from a second horizontal scan line of said source image;
• a look up table, coupled to said video memory, for reading said first pixel color address and outputting first output pixel color data from said look up table at the first pixel color address and reading said second pixel color address and outputting second output pixel color data from said look up table at the second pixel color address;
• weighting means, coupled to said look up table, for receiving said first output pixel color data and said second output pixel color data and outputting hybrid pixel color data as a weighted value of at least said first output pixel color data and said second output pixel color data;
• digital to analog converting means, coupled to said weighting means, for receiving said hybrid pixel color data and converting said hybrid pixel color data into an analog output video signal;
• and
• interlaced display means, coupled to said digital to analog converting means, for displaying said analog output video signal as a field of an interlaced display image,
• wherein said weighting means computes a weighted value of at least said first output pixel color data and said second output pixel color data according to at least one of a predetermined number of weighting schemes, each of said predetermined number of weighting schemes being applied to first and second output pixel color data from successive pairs of first and second horizontal scan lines, and said plurality of horizontal scan lines equals x horizontal scan lines divided into a plurality of groups of n horizontal scan lines, and said predetermined number of weighting schemes comprises n-1 weighting schemes applied to output pixel color data from successive pairs of first and second horizontal scan lines such that for each group of n horizontal scan lines of pixel color addresses read from said video memory, said weighting means outputs n-1 horizontal scan lines of hybrid pixel color data so as to vertically scale the source image by a ratio of n:n-1.

A system for displaying an interlaced video display image, comprising:

• a processor for receiving or generating a non-interlaced source image data;
• a single port video memory, coupled to said processor, for storing said non-interlaced source image data sequentially as a plurality of sequential horizontal scan lines of pixel data representing pixel color addresses;
• a controller, coupled to said video memory, for selectively reading from said video memory a first pixel color address from a first horizontal scan line of said source image and a second pixel color address from a second horizontal scan line of said source image;
• a look up table, coupled to said video memory, for reading said first pixel color address and outputting first output pixel color data from said look up table at the first pixel color address and reading said second pixel color address and outputting second output pixel color data from said look up table at the second pixel color address;
• weighting means, coupled to said look up table, for receiving said first output pixel color data and said second output pixel color data and outputting hybrid pixel color data as a weighted value of at least said first output pixel color data and said second output pixel color data;
• digital to analog converting means, coupled to said weighting means, for receiving said hybrid pixel color data and converting said hybrid pixel color data into an analog output video signal;
• interlaced display means, coupled to said digital to analog converting means, for displaying said analog output video signal as a field of an interlaced display image;
• luminance value calculating means, for calculating luminance values for said first and second output pixel color data;
• luminance storage means, for storing at least one of said calculated luminance values;
• luminance adjustment factor calculating means, coupled to said luminance value calculating means, said luminance storage means, and said weighting means, for calculating a luminance adjustment factor from calculated luminance values for said first and second output pixel color data and a previously stored luminance value for output pixel color data from a line adjacent to said first or second horizontal scan lines;
• and
• wherein said weighting means further selectively generates said hybrid pixel color data as a weighted average of said first output pixel color data and said second output pixel color data and said luminance adjustment factor.