Movement detector for television signals

• US 4,364,087 A
• Filed: 08/01/1980
• Issued: 12/14/1982
• Est. Priority Date: 08/01/1979
• Status: Expired due to Term

• Current Assignee: British Broadcasting Corporation
• Original Assignee: British Broadcasting Corporation
• Inventors: Storey, Richard, Roberts, Alan
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US06/174,426
• Time in Patent Office: 865 Days
• Field of Search: 358/105, 358/93, 358/106, 358/139, 340/258
• US Class Current: 348/155
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20
• CPC Class Codes: H04N 5/147 Scene change detection

Abstract

A movement detector for television signals measures the difference between maximum and minimum values of the movement components of a picture difference signal over a chosen interval. A television signal at an input (12) is delayed in a picture delay (2), and the delayed and undelayed signals subtracted in a subtractor (1) to form a picture difference signal. This is rectified in rectifier (3) and smoothed in a filter (4). A maximum detector (6) and a minimum detector (7) are coupled to the filter output and are re-set at prescribed intervals. A subtractor (8) determines the difference between the output of detectors (6) and (7) and this is compared with a reference value in a comparator (9), the output of which is sampled and stored in a store (10).

Claims

1. A movement detector for detecting movement in selected picture areas of a video signal, comprising:

an input for receiving an input video signal;

difference signal generating means connected to the input for generating a signal representative of the difference between the input signal on two different field scans;

extreme value determining means for determining for a selected area or areas of the picture maximum and minimum values of the difference signal; and

comparing means for comparing the value of said maximum value minus said minimum value with a reference value.

2. A movement detector according to claim 1, in which the difference signal generating means comprises a picture delay connected to the input and a combining circuit for determining the difference between the input signal and the picture-delayed signal.

3. A movement detector according to claim 1 or 2, including a two-dimensional (vertical, and horizontal/time) filter connected between the difference signal generating means and the extreme value determining means.

4. A movement detector according to claim 3, in which the filter comprises an integrator for providing an integration output, and a sample-and-hold circuit connected to the output of the integrator.

5. A movement detector according to claim 1, in which the extreme value determining means comprises a resettable maximum detector and a resettable minimum detector both connected to the output of the difference signal generating means.

6. A movement detector according to claim 5, in which the maximum and minimum detectors are reset at points which form a regular lattice on the picture.

7. A movement detector according to claim 1, in which the comparing means comprises a subtractor, and a comparator which is supplied with a reference value.