Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-05-15
2001-10-30
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C348S169000, C348S170000
Reexamination Certificate
active
06310920
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a moving picture encoding apparatus for performing a motion-compensated inter-frame predictive encoding and in particular, to a moving picture encoding apparatus having a camera controlling function that causes a camera to automatically track a moving object.
2. Description of the Related Art
Color information is used in one example of the automatic moving object tracking technology for keeping a moving object captured in the angle of a camera by moving the angle of the camera. In this example, the color information is extracted from a video signal in a designated detection block and registered as a specified color. The registered color is used for determining the motion of the object. In “Motion Vector Detection Circuit and Object Tracking Camera Apparatus Using the Circuit” by Matsumura et. al. disclosed in Japanese Patent Laid-Open Publication No. 8-125910, in order to prevent a color in a small area from being registered as a specified color of a block, only the color which is regarded as having high reliability on the basis of correlation is registered.
Japanese Patent Laid-Open Publication No. 4-126473 titled “Automatic Tracking Camera Apparatus” by Fujimoto et. al. discloses another example of the automatic moving object tracking technology. In this example, a contour of a moving object is extracted. Using the information in a closed space surrounded by the contour (color distribution information), a motion vector is detected by a known method. A camera is controlled to pan and tilt according to the motion vector. When the moving object goes out of the angle and become non-trackable, the width and height of the angle is controlled by zoom-out operations.
Still another example disclosed in “Global Zoom/Pan Estimation and Compensation for Video Compensation” (IEEE Conference of Acoustics, Speech and Signal Processing, 1991 M9, 4, pp. 2725-2728) is a method for decreasing the amount of generated information in a moving picture encoding device by globally compensating the motion of a camera using a global motion vector before performing conventional motion compensation. The global motion vector representing, for example, panning/tilting and zooming, is obtained by estimation based on local motion vectors for small blocks. However, the amount of calculation for obtaining the global motion vector from the local motion vectors is vast. Japanese Paten Laid-Open Publication No. 6-165164 titled “Dynamic Picture Processor” by Harasaki Hidenobu discloses a technique for decreasing the amount of the calculation by enlarging a motion vector search area and setting the area as a global area.
The aforementioned examples have the disadvantage that the quality of reproduced picture deteriorates to such a degree that a moving object becomes non-perceptible and the movement of the moving object becomes jerky while the camera is tracking the moving object because of the increase of generated information. Especially, the degree of the deterioration is intolerable when bit rate of transmission is low.
The reason of occurrence of the deterioration is explained as follows: When a camera automatically tracks a moving object, the background behind the moving object moves in the camera angle. Thus, the generated information increases. Then, in order to maintain a predetermined transmission rate, the moving picture encoding apparatus discards a part of generated information by coarsely performing the quantization, and decreasing the frame rate.
As explained above, when the camera tracks a moving object using a motion vector detected by a motion vector detecting means in a motion picture encoding apparatus, the background moves in the camera angle, the generated information increases, the motion picture encoding apparatus coarsely performs the quantization and decreases the frame rate in order to discard a part of the generated information, and the moving object become vague and the movement of the moving object becomes jerky.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a moving picture encoding apparatus comprising a camera controlling means that reduces the generated information originating from the background while the controlled camera is tracking a moving object in order to maintain high-resolution of the moving object and high frame rate.
According to the present invention, there is provided a moving picture encoding apparatus which comprises: motion vector detecting means for dividing moving picture data picked up by a camera into small blocks and detecting motion vectors corresponding to the small blocks; encoding means for motion-compensating the small blocks on the basis of the motion vectors so as to perform an inter-frame predictive encoding process; extracting means for extracting a moving object area on the basis of the motion vectors; calculating means for calculating a horizontal component and a vertical component of a representative vector of the moving object area on the basis of the motion vectors of all or a part of the moving object area; pan/tilt amount setting means for setting pan/tilt amounts on the basis of the horizontal component and the vertical component of the representative vector; outputting means for outputting a signal that represents the pan/tilt amounts; and means for causing the encoding means to finely perform quantization when the small block exists in the moving object area and to coarsely perform the quantization when the small block does not exist in the moving object area.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of the best mode embodiment thereof, as illustrated in the accompanying drawing.
REFERENCES:
patent: 5177608 (1993-01-01), Ohki et al.
patent: 5184216 (1993-02-01), Kobayashi
patent: 5210559 (1993-05-01), Ohki
patent: 5307170 (1994-04-01), Itsumi et al.
patent: 5926209 (1999-07-01), Glatt
patent: 6064436 (2000-05-01), Okada
patent: 4-126473 (1992-04-01), None
patent: 6-165164 (1994-06-01), None
patent: 06303589 A (1994-10-01), None
patent: 07298247 A (1995-11-01), None
patent: 08125910 A (1996-05-01), None
McGuireWoods LLP
NEC Corporation
Rao Andy
LandOfFree
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