Reduced bandwidth video transmission

• US 4,494,144 A
• Filed: 06/28/1982
• Issued: 01/15/1985
• Est. Priority Date: 06/28/1982
• Status: Expired due to Fees

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Brown, Earl F.
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US06/392,745
• Time in Patent Office: 932 Days
• Field of Search: 358/85, 358/133, 358/105, 179/2 TV, 179/18 SC, 381/53, 382/9
• US Class Current: 348/420.1
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 7/15 Conference systems
• CPC Class Codes: H04N 7/54 the signals being synchronous H04N21/23602, H04N21/23614, H04N21/2365, H04N21/2368, H04N21/4341, H04N21/4342, H04N21/4347, H04N21/4348 take precedence

Abstract

A bandwidth reduced teleconferencing system achieving good video presence. The bandwidth reduction is accomplished by dividing the video picture of the camera into segments, by determining the activity level within each segment and by transmitting the signal of each segment with a resolution level which is related to the activity level within the segment. The most active segment is transmitted at highest resolution while other segments are transmitted at lower resolutions.

Claims

1. A method for modifying the signal of a video camera to reduce the bandwidth of said signal, characterized by the steps of:

a. dividing the image represented by said video signal into image segments;

b. choosing at least one of said image segments in accordance with a predetermined attribute associated with each of said image segments and developing thereby selected image segments; and

c. developing a composite video signal corresponding to a high resolution signal for said selected image segments and a lower resolution signal for remaining ones of said image segments.

2. A method for developing video signals corresponding to an image derived from a video camera, comprising the steps of:

a. dividing said image into image segments;

b. choosing at least one of said image segments in accordance with a predetermined attribute associated with each of said image segments and developing thereby selected image segments; and

c. developing high resolution signals for said selected segments of said image and lower resolution signals for remaining ones of said image segments.

3. The method of claim 2 wherein said step of dividing said image into image segments is dynamically set based on the existing conditions of said image.

4. The method of claim 2 wherein said step of dividing into segments is arranged to have the actively changing regions of said image within a small number of said image segments.

5. The method of claim 2 wherein said step of choosing is responsive to sound emanating from said image segments.

6. A method for reducing the transmission bandwidth of a video camera comprising the steps of:

a. ascertaining regions of active change in the image transmitted by said video camera;

b. dividing said image into segments that encompass said regions of active change;

c. developing high resolution signals for those segments that encompass regions of most active change; and

d. developing lower resolution signals for remaining segments.

7. Apparatus for reducing the bandwidth of video camera signals comprising:

means for dividing the image represented by said video signals into segments; and

means for automatically altering said video signals in accordance with an attribute of said image within said segments to reduce said bandwidth of video camera signals to be transmitted.

8. Apparatus for reducing the signal bandwidth of a video camera comprising:

a segmentation processor for developing control signals that divide the image by said video camera into image segments, said control signals being developed in accordance with a predetermined attribute of said image segments;

first means for reducing the bandwidth of the output signal of said video camera in response to said segmentation processor; and

control means for coordinating the operation of said segmentation processor and said first means.

9. The apparatus of claim 8, wherein said first means comprises second means for deciding which image segments are to be transmitted at high resolution and which image segments are to be transmitted at lower resolution.

10. The apparatus of claim 9, wherein said second means comprises a plurality of microphones and third means, responsive to said plurality of said microphones for ascertaining the identity of the microphone possessing the strongest audio signal.

11. The apparatus of claim 8, further comprising a video camera for applying video signal to said first means.

12. The apparatus of claim 8, wherein said segmentation processor employs chroma-keying for developing said control signal that divides said image into said image segments.