Window generator

• US 4,814,884 A
• Filed: 10/21/1987
• Issued: 03/21/1989
• Est. Priority Date: 10/21/1987
• Status: Expired due to Fees

• Current Assignee: Martin Marietta Corporation
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Johnson, William K., May, Roger A.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/110,918
• Time in Patent Office: 517 Days
• Field of Search: 358/167, 358/160, 358/183, 364/521, 340/724, 340/747, 340/798, 340/799
• US Class Current: 348/596
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

A window generator is disclosed which provides a unique 6 bit target identification number for up to 63 target areas and one background area in a frame of serially scanned data. Any number of target areas can be identified by increasing memory width. The target numbers allow video pipeline processing circuitry to collect statistics separately for each target area. A target number is provided for each pixel as the image is scanned in a raster can format. The target areas are defined as rectangular sectors with background at all other non-target locations. The window generator has contained in a RAM the data necessary to define the window areas. This data is calculated and formatted off-line by a microprocessor and downloaded into the RAM. Information contained in the RAM represents the number of pixels between any two successive target area corners along with a two bit command word.

Claims

1. A window generator which receives a field of video data from an image data source and which provides rectangular subregions which may be located anywhere in a video frame of said field of video data when it is displayed on a video display, said window generator conducting said field of video data with said rectangular subregions imposed thereon to said video display, said window generator comprising:

a microprocessor which receives said field of video data from said image data source and which outputs said field of video data along with command signals which initiate said rectangular subregions;

a window memory which receives said field of video data and said command signals from said microprocessor, said window memory containing data necessary to define each of said rectangular subregions in terms of four corners, each of said corners being specified by a pixel identification number and a line identification number which indicates a precise location of each corner, and therefrom, each rectangular subregion as it appears in a frame displayed by said video display, said window memory outputting said field of video data and said rectangular subregions so that they may be forwarded to said video display;

a multiplexer means which receives, combines and outputs said field of video data with said rectangular subregions from said window memory to produce output signals; and

a line memory which receives and conducts said output signals from said multiplexer means to said video display, said line memory also receiving and storing said data defining each of said rectangular subregions.

2. A window generator, as defined in claim 1, wherein said line memory outputs said data defining each of said rectangular subregions, and wherein said multiplexer means includes a comparator which receives and compares said data defining said rectangular subregions from said line memory with data defining rectangular subregions from said window memory, said comparator designating an overlapping area between a first and second overlapping rectangular subregion as belonging uniquely to the first overlapping subregion when the first overlapping subregion has a line identification number which places its lowest corners at an area lower on said video frame on said display than any of said second overlapping rectangular subregion, said comparator designating said overlapping area as belonging to said second overlapping rectangular subregion otherwise, said comparator thereby resolving ambiguity in designating an identity for said overlapping area between the first and second overlapping rectangular subregions.

3. A window generator, as defined in claim 2, wherein said window memory has a memory address which contains said data defining said rectangular subregions, and said window memory outputs a delta field which includes pixel and line designations that define all of said rectangular subregions in said video frame, and said window generator includes a means for automatically generating additional rectangular subregions within said video frame, said generating means receiving said delta field from said window memory and generating additional rectangular subregions by incrementing the memory address in said window memory when new entries in said field of video data transcend the existing rectangular subregions used by the window generator.

4. A window generator, as defined in claim 3, wherein said means for automatically generating additional rectangular subregions comprises:

a delta counter which receives said delta field from said window memory and counts pixel intervals between said rectangular subregions, said delta counter producing an output signal to automatically access a new entry in the window memory when a pixel interval between subregions which share common lines in the video frame is not greater than zero, said delta counter thereby allowing the window generator to correct overlap between the rectangular subregions;

a frame initialization circuit which forwards a frame synchronization command when said field of video data from said data source comprises a plurality of digitized frame of serially scanned data and a start of a new frame is detected,

an OR gate which produces an output signal when receiving said synchronization command from the frame initialization circuit, said OR gate also producing an output signal when receiving the output signal from the delta counter;

a memory address counter which receives and counts the output signal from the OR gate to designate a new rectangular target area by forwarding a new delta field which equals the counts of the output signal of the OR gate., and

a buffer which receives and conducts the new delta field from the memory address counter to the memory address of the window memory.

5. A window generator as defined in claim 4 wherein said multiplexer means includes a subtractor which receives and decrements a line count in the data which defines a rectangular subregion from the line memory, said subtractor outputting to the window memory a new rectangular subregion with a reduced vertical size, said subtractor thereby allowing users of the window generator to vertically adjust a rectangular subregion by reducing its vertical size in the video frame.