Method for compressing and decompressing moving picture information and video signal processing system

• US 6,373,892 B1
• Filed: 11/13/1995
• Issued: 04/16/2002
• Est. Priority Date: 11/17/1994
• Status: Expired due to Fees

• Current Assignee: Sega Enterprises LTD. (SEGA Sammy Holdings Inc.)
• Original Assignee: Sega Enterprises LTD. (SEGA Sammy Holdings Inc.)
• Inventors: Saitoh, Tadashi, Ichien, Toru, Okunoki, Yutaka, Kimura, Junichi
• Primary Examiner(s): LEE, Y YOUNG
• Application Number:
  US08/554,965
• Time in Patent Office: 2,346 Days
• Field of Search: H04/N 1.102, 348/390, 348/578, 348/585, 348/597, 348/580, 348/571, 348/575, 348/584, 348/586, 348/587, 348/396, 348/590, 345/113, 364/413.22, 382/260, 386/46
• US Class Current: 375/240.08
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/4318 by altering the content in the rendering process, e.g. blanking, blurring or masking an image region image enhancement or restoration in general G06T5/00
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 5/262 Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
• CPC Class Codes: H04N 5/275 Generation of keying signals

Abstract

A method for compressing and decompressing moving picture information wherein a key signal is correctly reproduced and coding is efficiently carried out, and a video signal processing system for implementing the method. At the time of coding a video signal, conversion is carried out for make large a distance between an ordinary digitized video signal and a key signal indicative of whether an image indicates background or foreground for data compression. At the time of decoding the coded video signal, the video signal and key signal of the decompressed image are separated based on a predetermined threshold and reverse conversion opposite to the coding mode is carried out. Since the coding is carried out with the ordinary video signal separated from the key signal, the video signal and the key signal can be separated by a suitable threshold from the compressed and then decompressed image and thus the video signal and key signal can be correctly reproduced.

Claims

1. A method for reproducing moving picture information from a compressed video signal, said compressed video signal including coded original video signal information including moving picture information to be digitized and added with a key signal indicative of background or foreground so as to cause values of signal levels indicative of the original video signal to be offset from a value of a signal level of the key signal indicative of background, said method comprising the steps of:

decoding the compressed video signal;

separating the key signal from the video signal in a comparison circuit, wherein said decoded video signal is compared with a preset threshold to judge whether or not the decoded video signal includes said key signal indicative of background and outputting the key signal indicative of contents corresponding to the judgement result; and

performing a reverse transformation using a clipping circuit receiving as an input the decoded video signal, to extract a video signal other than the key signal, and using a correction circuit to correct the extracted video signal to cause offset level distances between the values of the original video signal and the value of the key signal to be restored to respective original values.

2. A method as set forth in claim 1, wherein the signal level of said preset threshold is selected so as to separate the video signal from the key signal indicative of background to retrieve a video signal and a reproduction key signal from said decoded video signal on the basis of said preset threshold.

3. A method as set forth in claim 2, wherein said preset threshold is prepared to have a plurality of values, and any of the values of said preset threshold is selected to adjust reproduction of the decoded video signal and key signal to match a separation degree between a foreground and a background at the time of coding an original video signal to produce said compressed video signal.

4. A method as set forth in claim 1, wherein key signals of both pixels adjacent to a target pixel of reproduction video information of line scan or raster scan are referred to, and, when either one of said key signals indicates background, the key signal of a current pixel is made to have a value indicative of background.

5. A method as set forth in claim 1, further comprising the step of converting the video signal corrected by said correction circuit to a video signal suitable for a display unit.

6. A method as set forth in claim 1, wherein said preset threshold is selectively set, and wherein reproduction key signals, with respect to each pixel of said decoded video signal of a line scan display, are made to have values indicative of the background when either one of the reproduction key signals of the pixels adjacent to a target pixel is indicative of the background.

7. A video signal reproducing system for use in reproducing moving picture information from a compressed video signal, said compressed video signal including coded original video signal information including moving picture information to be digitized and added with a key signal indicative of background or foreground so as to cause values of signal levels indicative of the original video signal to be offset from a value of a signal level of the key signal indicative of background, said video signal reproducing system comprising:

a decoder which decodes the compressed video signal;

a clipping circuit functionally connected to said decoder and receiving as an input signal the decoded video signal, said clipping circuit extracting a video signal other than said key signal indicative of background or foreground;

a correction circuit connected with an output of said clipping circuit to correct the video signal to cause the offset level distances between the values of the original video signal and the value of the key signal to be restored to respective original values;

a comparison circuit functionally connected to said decoder and receiving the decoded video signal, said comparison circuit comparing said decoded video signal with a preset threshold to judge whether or not the decoded video signal includes the key signal indicative of background and outputting the key signal indicative of contents corresponding to the judgement result; and

a synthesizer circuit functionally connected with outputs of said correction and comparison circuits, said synthesizer circuit outputting a video signal indicative of background when the key signal indicates the background on the basis of the key signal issued from said comparison circuit and outputting a video signal from said correction circuit when the key signal is indicative of foreground.

8. A video signal reproducing system as set forth in claim 7, wherein said decoder includes a decompression circuit decompressing the compressed video signal.

9. A video signal reproducing system for use in reproducing a digital video signal of a line scan type including moving picture information, comprising:

a clipping circuit receiving an input digital video signal subjected to data formatting and having a key signal indicative of background or foreground assigned to a most significant bit and having a least significant bit removed, the clipping circuit extracting a video signal of each pixel other than said key signal and outputting the extracted video signal;

a correction circuit connected with an output of said clipping circuit to correct the extracted video signal in a range of values taken by an original video signal;

a comparison circuit functionally connected to receive the input digital video signal, said comparison circuit comparing said input digital video signal with a preset threshold to judge whether or not the input digital video signal includes the key signal indicative of background and outputting the key signal indicative of contents corresponding to the judgement result; and

a synthesizer circuit functionally connected with outputs of said correction and comparison circuits, said synthesizer circuit outputting a video signal indicative of background when the key signal indicates background on the basis of the key signal issued from said comparison circuit, and outputting a video signal from said correction circuit when the key signal is indicative of foreground.

10. A method for decoding a digital video signal of a line scan type including moving picture information, comprising the steps of:

using a clipping circuit, extracting, from an input digital video signal subjected to a data formatting and having a key signal indicative of background or foreground assigned to a most significant bit and a least significant bit removed, the video signal of each pixel other than said key signal;

in a correction circuit, correcting said extracted video signal to have values in a range of values taken by an original video signal;

in a comparison circuit, comparing a preset threshold with said input digital video signal to judge whether or not said input digital video signal includes the key signal indicative of background and to generate the key signal corresponding to the judged contents; and

in a synthesizer circuit, outputting a video signal indicative of the background when the key signal indicates the background on the basis of the generated key signal and outputting said corrected video signal when the key signal indicates foreground.