JPH0771206B2 - Automatic tracking imaging device - Google Patents

Description

The present invention relates to an automatic tracking image pickup device which is used in, for example, a videophone device and extracts a moving object region such as a person from an image pickup screen.

"Prior Art" In a videophone device that realizes a face-to-face call between two parties who are distant from each other using a low bit rate transmission line, a process of reducing the number of pixels per screen is required to reduce the amount of transmission information. Has been done. In this method, when the image of a person is captured in a wide range including the background portion, the resolution of the person part is lowered and the reproduced person image becomes unclear. Therefore, it is necessary to project the person image large on the screen. If a person moves while the image of the person is displayed on the screen, a part of the person may come off the screen.

In order to solve this, it is considered that a monitor device is provided to constantly monitor the appearance of the person being photographed so that the person is always shown on the monitor screen. With this method, you must always be aware of whether you are in the picture or not, and that distracts you from videophone conversations. In addition, a method of moving an image pickup unit, for example, a TV camera so as to follow a person image when it moves may be considered, but this method has a problem that a mechanism part such as an electric camera platform for a TV camera and an electric zoom lens becomes too large. There is a point.

An object of the present invention is to provide an automatic tracking image pickup device which does not move from a screen when a moving object moves without providing a mechanism part such as an electric platform.

[Means for Solving Problems] According to the present invention, an n ₁ × n ₂ pixel screen is imaged by an imaging device, an output video signal thereof is delayed by one or more frames by a frame memory, and the delayed video signal and the imaging are performed. The difference from the non-delayed video signal from the device is taken out to detect the moving area, which is judged by the moving object area and the moving object judging means. Including the judgment moving object area, it is smaller than n ₁ × n ₂ screen km ₁ × km ₂ screen (n ₁ > km ₁ , n ₂ > km ₂ ,
A moving object region extracting means extracts a video signal of a region formed by m ₁ and m ₂ having predetermined values and k is a natural number of 1 or more) from the output video signal of the image pickup device. Pixels are thinned out by the thinning-out means, and the extracted video signal is output as a video signal of an m ₁ × m ₂ screen.

"Embodiment" FIG. 1 shows an embodiment of the present invention. Video output from the image pickup device 11 such as a television camera is supplied to the frame memory 12, the difference extraction circuit 13, and the person area extraction circuit 14. The frame memory 12 delays the input video by one frame and supplies it to the difference extraction circuit 13. The output of the difference extraction circuit 13 is supplied to the person area determination circuit 15, and the person area is determined. A human region is extracted by a human region extraction circuit 14 from a video signal from the image pickup device 11 according to an instruction from a human region determination circuit 15, and is supplied to a thinning circuit 16.

The operation of this system will be described with reference to FIG.

The _1st frame (FIG. 2A) of the output video signal from the image pickup device 11 having the number of pixels of n ₁ × n ₂ is a frame memory.
Accumulated in 12. The accumulated video signal of the l-th frame and the output video signal of the next (l + 1) -th frame (FIG. 2B) from the video device 11 are subtracted from each other by the difference extraction circuit 13, and both frame video signals are processed. The difference between them is extracted.
That is, a moving area is extracted between the 1st frame and the (l + 1) th frame. In the person area determination circuit 15, k smaller than the n ₁ × n ₂ pixel area including this change area (FIG. 2C)
A region consisting of m ₁ × km ₂ pixels (m ₁ and m ₂ are predetermined values, k is a natural number of 1 or more) is designated, and this region is determined to be a person region. An area extraction instruction signal for extracting this person area portion from the output video signal of the image pickup apparatus 11 is given to the person area extraction circuit 14, and the person area extraction circuit 14 receives the input from the image pickup apparatus 11 based on the area extraction instruction signal. From the image km ₁ × km ₂
An image of only the area (FIG. 2D) is created and input to the thinning circuit 16. The decimating circuit 16 decimates the pixels of the created image and outputs it as an image signal of a screen of m ₁ × m ₂ (FIG. 2E). Since this video signal is thinned out, it can be transmitted through a low bit rate transmission line.

The person is slightly moving even in a stationary state, and the person area can be detected. The present invention can be applied to the case where not only a person but also a region of another moving object is similarly tracked. The delay amount by the frame memory 12 is not limited to one frame, and may be a plurality of frames.

[Advantages of the Invention] As described above, the device of the present invention captures a relatively wide range including a moving object such as a person, and uses the movement of the moving object in the area surrounding the moving object from within the screen. Since a new video signal is taken out as a new video signal, a special mechanical component is not required, and even if the moving object slightly moves, it is possible to always image the moving object as a center, and the moving object can also be imaged. There is an advantage that a moving object can be imaged with almost the same size even when the moving object approaches or leaves. Further, when the present invention is applied to a videophone, the speaker does not need to have a conversation while paying attention to his monitor image, and can focus his attention on the conversation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic tracking imaging device,
FIG. 2 is a diagram showing an example of an input / output video screen of each part of FIG. 11: image pickup device, 12: frame memory, 13: difference extraction circuit, 1
4: Human area extraction circuit, 15: Human area determination circuit, 16: Thinning circuit.

Claims (1)

[Claims] 1. An image pickup device for picking up an n ₁ × n ₂ pixel screen, a frame memory for delaying an output video signal of the image pickup device by N frames (N is an integer of 1 or more), and a delayed image in the frame memory. Moving object determination means for determining a moving object area by extracting a difference between a signal and a video signal that is not delayed from the image pickup device and detecting a moving area, and n ₁ × n _{2 including the} determined moving object area Only the video signal of a region smaller than the screen is composed of a km ₁ × km ₂ screen (n ₁ > km ₁ , n ₂ > km ₂ , m ₁ , m ₂ is a predetermined value, k is a natural number of 1 or more). An automatic tracking image pickup apparatus having moving object area extraction means for extracting from an output video signal of an image pickup apparatus and thinning means for thinning out pixels of the extracted video signal to create a video signal composed of m ₁ × m ₂ pixels.