Managing letterbox signals with logos and closed captions

A video control system, comprising:

• a video display means having a wide format display ratio;
• a letterbox processor for determining when a picture represented by a video signal has a letterbox format, said letterbox processor having means for evaluating video content of said video signal;
• and
• means for restricting operation of said letterbox processor to a vertical range of horizontal lines in each vertical scanning cycle of said video signal.

A video display control system, comprising:

• a video display means having a wide format display ratio;
• a letterbox processor for determining when a picture represented by a video signal has a letterbox format;
• and,
• means for restricting operation of said letterbox processor to a vertical range of horizontal lines in each field of said video signal, said vertical range excluding those of said horizontal lines in each said field which correspond in time to vertical blanking and, when present, head switching transients.

A video display control system, comprising:

• a video display means having a wide format display ratio;
• a letterbox processor for determining when a picture represented by a video signal has a letterbox format;
• and,
• line counting means for initiating a letterbox detection enable signal at a first line count and terminating said enable signal at a second line count, said enable signal restricting operation of said letterbox processor to a vertical range of horizontal lines in each field of said video signal.

A video display control system, comprising:

• a video display means having a wide format display ratio;
• a letterbox processor for determining when a picture represented by a video signal has a letterbox format;
• first and second comparators, responsive to first and second predetermined line counts respectively, and both responsive to a running line count;
• and,
• a flip/flop responsive to each of said comparators, for initiating an enable signal when said running line count reaches said first predetermined count and terminating said enable signal when said running line count reaches said second predetermined count, said enable signal restricting operation of said letterbox processor to a vertical range of horizontal lines in each field of said video signal.

A video display control system, comprising:

• a video display means having a wide format display ratio;
• means for determining when a picture represented by a video signal is indicative of said picture having a letterbox format in which an active video portion of said picture is positioned between upper and lower border areas, said letterbox format picture sometimes having auxiliary information positioned in different portions of said border areas;
• means responsive to said letterbox determining means for enlarging said picture in size to substantially fill said video display means with said active video portion when said video signal is determined to have said letterbox format;
• and,
• means for inhibiting said determining means from responding falsely by restricting operation of said determining means to a predetermined portion of each field likely to exclude said auxiliary information, when present.