System for raster imaging with automatic centering and image compression

• US 5,422,996 A
• Filed: 12/09/1993
• Issued: 06/06/1995
• Est. Priority Date: 04/10/1989
• Status: Expired due to Term

• Current Assignee: NVIDIA Corporation
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Patil, Suhas S., Reddy, Dayakar C., Bassetti, Chester F. Jr.
• Primary Examiner(s): Nguyen, Phu K.
• Application Number:
  US08/164,312
• Time in Patent Office: 544 Days
• Field of Search: 395/144, 395/145, 395/148, 395/63, 395/83, 395/162, 395/164, 400/63, 400/83, 358/101, 358/106, 358/107, 358/111, 345/189, 345/190, 345/191
• US Class Current: 345/501
• CPC Class Codes: G09G 2340/0421 Horizontal resolution change
• CPC Class Codes: G09G 2340/0471 Vertical positioning
• CPC Class Codes: G09G 2340/0478 Horizontal positioning
• CPC Class Codes: G09G 2340/0485 Centering horizontally or vertically
• CPC Class Codes: G09G 2360/04 Display device controller operating with a plurality of display units
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

The system provides for vertical or horizontal centering, or both, without the use of a memory frame buffer, of raster image data whose start time and duration cannot be controlled. The centering is accomplished by controlling the frame start time and line start time of the overall display of the raster imaging surface. This is accomplished in the case of vertical centering by detecting the time of the beginning of the first or last line, or both, of the total lines of the raster image data to be displayed an controlling the start time of a subsequent one of the frames based on that detected time. Horizontal centering is carried out by detecting the time of the beginning of the first or last column, or both, of the columns in one or more of the lines of the raster image data and controlling the start time of subsequent ones of the lines based on that detected time.

Claims

1. A system for compressing raster-image data in sequential frames in a single data stream which is converted to two streams of pixels for each of said sequential frames of said single data stream;

said two pixel streams being suitable for controlling images on a raster imaging surface having first and second segments therein;

said imaging surface being responsive to signals representing characteristics such as color or intensity of pixels to produce raster images in the portions of said segments receiving said signals, said images in said segments within a frame being produced by a raster image-producing means in a plurality n of sequentially produced lines in said imaging surface, said system comprising;

a first and a second transformation module having inputs and outputs;

means for supplying said single stream of pixels to said first and said second transformation modules;

means for utilizing the output from said first transformation module to alternately produce a raster image on the first and second segments for a frame;

means for delaying the output from said second transformation module to alternately produce a raster image on the second and first segments for the frame;

means for deleting selected ones of said pixels in said stream of pixels for each one of said plurality of n lines; and

means for compressing the remaining ones of said pixels for each one of said n lines to reduce the width of said produced image.

2. A system in accordance with claim 1 including skip data control means connected to control said outputs of said first and said second transformation modules;

and

means for energizing said skip data control means to generate a skip data control signal to selectably delete said selected ones of said pixels in said pixel stream from said outputs of said first and said second transformation modules.

3. A system in accordance with claim 2 including first and second shift registers having inputs connected to the outputs of said first and said second transformation modules, and means for supplying said skip data control signal to said first and said second shift registers to selectably delete said selected ones of said pixels from said pixel stream.

4. A system in accordance with claim 1, wherein said compressing means comprises a first shift register having an input terminal for receiving said output of said first transformation module.

5. A system in accordance with claim 4, wherein said compressing means further comprises a second shift register having an input terminal for receiving said output of said second transformation module.

6. A system in accordance with claim 5, wherein said deleting means comprises an AND gate having an output terminal connected to a clock input terminal of said first shift register and to a clock input terminal of said second shift register.

7. A data compression system for compressing raster image data for driving a raster imaging surface comprising a plurality K of segments, said raster image data being received in a single data stream and converted to a plurality K of streams of pixels for driving said K segments, said segments being responsive to receipt of signals from said K streams of pixels to produce raster images, said images within a frame being produced in a plurality n of sequentially produced lines in said imaging surface, said system comprising:

means for converting said single data stream to K output streams of pixels;

a plurality K of receiving circuits each having an input for receiving respective ones of said K output streams of pixels, each of said receiving circuits having an output;

means coupled to said receiving circuits for selectably deleting ones of said pixels in said K streams of pixels;

means for compressing the remaining ones of said pixels to reduce the width of the produced image;

means for applying ones of said K streams of pixels to corresponding ones of said K segments; and

means for delaying the application of other of said K streams of pixels to corresponding ones of said K segments.

8. The system of claim 7, wherein said deleting means further comprises a control means for generating a control signal coupled to said K receiving circuits to selectably delete selected ones of said pixels for each one of said plurality of n lines in said K streams of pixels.

9. The system of claim 8, wherein said means for compressing comprises a plurality K of shift registers, one for each of said K streams of pixels, each of said K shift registers having a clock input terminal for receiving said control signal from said control means and a data input terminal for receiving the associated stream of pixels, wherein said K shift registers load a pixel in response to said control signal.

10. The system of claim 9, wherein said control means comprises an AND gate having an output terminal connected to said clock input terminal of each of said K shift registers.

11. The system according to claim 7, wherein said receiving circuits comprise transformation modules.