JP2677224B2 - Image capture device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image capturing device for capturing a moving image and storing it in a file device.

[0002]

2. Description of the Related Art A moving image output from a television camera, a VTR device or the like is captured and stored in a file device.
It has been conventionally performed to select a frame having an appropriate composition from the stored moving images and perform processing such as combining with a character. When capturing a moving image for such a purpose, it is not necessary to capture all the frames of the moving image, and it is sufficient to capture only the frames that have changed to some extent. Can be reduced.

Therefore, in order to capture only the frames that have changed to some extent, for example, Japanese Patent Laid-Open No. 3-65.
It is conceivable to use the technique described in Japanese Patent Publication No. 843. This technique calculates a difference between a specific frame of a moving image output from a television camera or the like and a subsequent frame (for example, a sum of absolute values of differences in luminance of corresponding pixels), and calculates the difference. Only the frames in the section exceeding the threshold are stored in the file device. That is, in a section where the image is still, since there is generally a strong correlation between two consecutive frames, the difference between the frames rarely exceeds the threshold value, and the frames in such a section are not stored in the file device. Therefore, only frames that change to some extent are saved in the file device.

[0004]

However, the above-mentioned conventional technique determines whether or not to save a frame based on whether or not the difference between two consecutive frames exceeds a threshold value. There was such a problem.

That is, between the first frame and the second frame, between the second frame and the third frame, ..., (N-
1) Only a slight change occurs between two consecutive frames such as between the frame and the Nth frame, and even if the difference does not exceed the threshold value, the two consecutive frames are separated from each other. Very small changes between two frames may be accumulated and become a large change. In such a case, in the above-described conventional technique, it is determined whether or not to save the frame based on the difference value between two consecutive frames, and therefore, it is possible to save two frames apart from each other which causes a large change. Can not.

Therefore, an object of the present invention is to provide an image capturing device capable of capturing two frames apart from each other, in which a slight change exists in a continuous section and there is some change between them. .

[0007]

In order to achieve the above-mentioned object, the present invention achieves the above object, a frame capturing means for capturing a moving image on a frame-by-frame basis, a file device for storing a frame of the moving image, and a file device finally stored in the file device. Frame difference detection means for detecting a difference between the captured frame and the frame captured by the frame capture means, and the captured frame in the file device based on the difference detected by the interframe difference detection means. It is provided with a significant frame judging means for judging whether or not the frame is a significant frame to be stored, and an import control device for storing only the frame judged as the significant frame by the significant frame judging means in the file device. .

Further, the present invention achieves an object of enabling a frame to be stored in a file device as a significant frame even when only a part of the frame is significantly changed, and whether or not the frame is a significant frame. In order to achieve the purpose of enabling the determination of
The inter-frame difference detection means calculates a difference between corresponding blocks when the frame last stored in the file device and the frame captured by the frame capture means are divided into a plurality of blocks. If the difference between the blocks detected by the inter-frame difference detection means includes at least one difference that exceeds the threshold, the significant frame determination means detects the frame captured by the frame capture means as the difference. It is determined that the frame is a significant frame to be stored in the file device.

Further, the present invention achieves the object of speeding up the detection of the difference between frames.
The preceding significant frame feature information holding means is provided, and the inter-frame difference detection means includes the feature information for each block of the significant frames last stored in the file device held in the immediately preceding significant frame feature information holding means, and The difference between corresponding blocks is detected based on the characteristic information of each block of the frame captured by the frame capturing means, and the frame captured by the frame capturing means is determined to be a significant frame by the significant frame determining means. By doing so, the characteristic information of each block of the frame captured by the frame capturing means is stored in the immediately preceding significant frame characteristic information holding means.

Further, according to the present invention, in order to achieve the object that the calculation of the characteristic information of a block can be speeded up, the inter-frame difference detection means preliminarily stores the characteristic information of each block in each block. The calculation is performed by using only the information about some of the defined pixels.

[0011]

The frame capturing means captures the moving image frame by frame, and the inter-frame difference detecting means detects the difference between the frame captured by the frame capturing means and the frame last stored in the file device.

The significant frame determining means determines whether the frame captured by the frame capturing means is a significant frame to be stored in the file device based on the difference detected by the inter-frame difference detecting means. Then, when the significant frame determination means determines that the frame is a significant frame, the capture control device stores the frame captured by the frame capture means in the file device. In this way, by determining whether or not the frame is the significant frame to be stored based on the difference between the frame last stored in the file device and the frame captured by the frame capturing means, it is possible to determine whether there is a significant frame to be stored. Even if there is only a very small difference, very small differences between two consecutive frames are accumulated, and the frame captured by the frame capturing means has a large difference from the frame last stored in the file device. When it becomes, the frame is stored.

Further, the inter-frame difference detecting means, for example, calculates the difference between corresponding blocks when the frame last stored in the file device and the frame captured by the frame capturing means are divided into a plurality of blocks. It is detected as a frame difference, and the significant frame determination means
If even one of the differences between the blocks exceeds the threshold, it is determined that the frame captured by the frame capturing means is a significant frame to be stored in the file device. Therefore, even if only a part of the frame changes significantly, the frame can be saved, and if there is at least one difference among the blocks that exceeds the threshold value, the frame is significant. Since it is determined that there is a frame, it can be determined at high speed whether or not the frame is significant.

When it is determined that the frame captured this time is a significant frame, the inter-frame difference detection means determines the characteristic information of each block of the frame (for example, the average value of the luminance of the pixels in each block). The characteristic information of each block held in the immediately preceding significant frame characteristic information holding means is held in the immediately preceding significant frame characteristic information holding means, and when the frame fetching means detects the difference from the next fetched frame. Use to detect the difference.

Further, the inter-frame difference detecting means calculates the characteristic information of each block by using only the information of a part of pixels set in advance in each block.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, which comprises a moving image capturing device 1 and a video output device 2 such as a VTR.

The moving image capturing device 1 includes a frame capturing means 11, a frame memory 12, and a file device 1.
3, a capture control device 14, an inter-frame difference detection means 15, a significant frame determination means 16, and an immediately preceding significant frame characteristic information holding means 17.

The frame capturing means 11 captures the moving image output from the video output device 2 in frame units,
It has a function of storing in the frame memory 12. For example,
If an NTSC format video signal is output from the video output device 2, the video signal is subjected to AD conversion and then the frame memory 1
2 is stored. At that time, the number of pixels in the horizontal and vertical directions is AD.
Depends on the sampling frequency of the conversion. In general, 1
Information per pixel is luminance (Y), color difference (RY, B-
By assigning 8 levels to each of Y), sufficient quality as a color image can be obtained. Also, one frame (3
Since the image data for 1/0 second) is divided into an odd field and an even field, these are collectively set as image data for one frame.

The inter-frame difference detecting means 15 has a function of detecting a difference between the feature information of the frame stored in the frame memory 12 and the feature information of the frame last stored in the file device 13.

The significant frame determining means 16 determines whether the difference detected by the interframe difference detecting means 15 exceeds a predetermined threshold value or not.
It has a function of determining whether or not the frame stored in is a significant frame to be stored in the file device 13.

The capture control device 14 has a function of controlling the storage of the frames stored in the frame memory 12 in the file device 13, a function of instructing the start and stop of the operation of the frame capture means 11, and the like.

FIG. 2 is a flow chart showing an example of processing of this embodiment. The operation of this embodiment will be described below with reference to the drawings.

First, the user operates the video output device 2 to output a moving image, and then operates the moving image capturing device 1.

As a result, the moving image capturing apparatus 1 is shown in FIG.
The process shown in the flowchart of FIG.

In the moving image capturing apparatus 1, first, the capturing control apparatus 14 immediately sets the predetermined frame characteristic information (for example, the characteristic information when all the pixels in the frame are 0, that is, the black level). It is stored in the immediately preceding significant frame characteristic information holding means 17 as the characteristic information of the significant frame.
(Step S1). Here, the process of step S1 is performed because, in the initial state, there is no immediately preceding significant frame.

Next, the capture controller 14 operates the frame capture means 11 (step S2). As a result, the frame capturing means 11 captures one frame of the moving image output from the video output device 2 and stores it in the frame memory 12.

When the frame capturing means 11 writes one frame of moving image in the frame memory 12, the capturing control device 14 instructs the frame capturing means 11 to stop the operation (step S3). This is to prevent the frame stored in the frame memory 12 this time from being destroyed by the next frame before the processing is completed.

Thereafter, the capture control device 14 instructs the interframe difference detection means 15 to detect the interframe difference (step S4). As a result, the inter-frame difference detection means 15 calculates the characteristic information of the frame currently stored in the frame memory 12, and then calculates the calculated characteristic information and the immediately preceding significant frame characteristic information holding means 1.
The difference with the feature information held in 7 is obtained and passed to the significant frame determination means 16.

Here, as the characteristic information of the frame, for example, the average value and the sum of the luminance of the pixels in the frame, and FIG.
, The frame is a block B1 of m × n pixels.
It is possible to use the average value, the sum, etc. of the luminance of the pixels in each block when divided into 1, B12, .... The luminance component is used because it has a property of containing a lot of shape information of the object. Further, when the average value of the luminance in the block is used as the characteristic information of the frame, the average value of an arbitrary number X (1 ≦ X ≦ mn) of pixels in the block can be used as the characteristic information. In this way, the number of average value calculations can be reduced to X / mn. However, if X is made small, the error becomes large. Therefore, for example, when the block size is 8 × 8, about 8 to 16 pieces are suitable.
Further, as shown in FIG. 4, when the X pixels are selected so that the positions of the X pixels are as evenly spaced as possible, the information in the block is evenly included, so that the error is reduced. can do.

The difference between the feature information of the frame stored in the frame memory 12 and the feature information of the frame last stored in the file device 13 is calculated every time a new frame is stored in the frame memory 12. The characteristic information of each of the frame stored in the frame memory 12 and the frame finally stored in the file device 13 is calculated,
Although it can be obtained based on them, the last significant frame characteristic information holding means 1 stores the characteristic information of the frame last stored in the file device 13 as in this embodiment.
The difference processing can be speeded up by holding the value in No. 7 and using the feature information held in the immediately preceding significant frame feature information holding unit 17 to obtain the difference. When the average value or the sum of the brightness of the pixels in the block is used as the feature information, the set of differences between the corresponding blocks is set as the difference of the feature information between frames.

When the difference between the feature information between the frames is passed from the inter-frame difference detecting means 15, the significant frame determining means 16 determines whether or not the difference exceeds a predetermined threshold value, that is, the frame memory 12. It is determined whether the stored frame is a significant frame to be stored in the file device 13 or a frame that does not need to be stored, and the determination result is passed to the capture control device 14.

Here, when the inter-frame difference detection means 15 outputs the difference between the corresponding blocks as the inter-frame difference, the significant frame determination means 16 includes 1 in it.
At any time when it is detected that there is a difference exceeding the threshold value, the capture control device 14 is notified that the frame stored in the frame memory 12 is a significant frame.

As described above, a set of differences between blocks is used as a difference between frames, and if there is at least one difference exceeding the threshold value, it is determined to be a significant frame. The significant frame determination process can be speeded up, and it is possible to determine a significant frame even when only a part of the moving image changes significantly. On the other hand, if the average value of all pixels is calculated without blocking, even if there is a large partial change, the average value is averaged, so the threshold value is not exceeded, and it is determined that the frame is not a significant frame.

If the frame controller 12 is informed by the significant frame determination means 16 that the frame stored in the frame memory 12 is a significant frame (Yes in step S5), the frame controller 12 and the file device 13 will be described. And stores the frame stored in the frame memory 12 in the file device 13 (step S
6) Further, the inter-frame difference detecting means 15 is instructed to hold the characteristic information of the frame stored in the frame memory 12 in the immediately preceding significant frame characteristic information holding means 17 (step S7). By receiving this instruction,
The inter-frame difference detection means 15 stores the previously calculated feature information of the frames stored in the frame memory 12 in the immediately preceding significant frame feature information holding means 17. As described above, when the difference between the last significant frame stored in the file device 13 and the frame stored in the frame memory 12 exceeds the threshold value, the frame stored in the frame memory 12 is determined to be a significant frame. By storing the data in the file device 13 in a continuous manner, it is possible to capture two distant frames in which a slight change exists in a continuous section and there is a certain change between them.

Thereafter, the capture controller 14 instructs the frame capture means 11 to cancel the stop (step S8). As a result, the same processing as described above is restarted. Although the moving images of several frames disappear while the operation of the frame capturing means 11 is stopped, it suffices to store only the frames having a certain change. There is no problem.

When the significant frame determination means 16 notifies that the frame stored in the frame memory 12 is not a significant frame (step S5 is N
o), the capture control device 14 performs the process of step S8.

The video output device 2 repeats the above processing until the user instructs the stop (No in step S9).

[0039]

As described above, according to the present invention, the frame captured by the frame capturing means is stored in the file device based on the difference between the frame last stored in the file device and the frame captured by the frame capturing means. It is configured to determine whether or not it is a significant frame, and even if there is a very small difference between two consecutive frames, a very small difference between two consecutive frames is accumulated, The frame is stored when the frame captured by the frame capturing unit has a large difference from the frame stored last in the file device, so that a slight change occurs within a continuous interval. It can also capture two separate frames that are present and have some variation between them.

Further, according to the present invention, when the frame last stored in the file device and the frame captured by the frame capturing means are divided into a plurality of blocks, a difference between corresponding blocks is detected as a difference between the frames. Then
If there is at least one block that exceeds the threshold value among the differences between blocks, it is determined as a significant frame. Therefore, even if a part of the frame changes significantly, that frame is significant. The frame can be saved in the file device, and the process of determining whether or not the frame is significant can be sped up.

Further, according to the present invention, when the frame captured this time is a significant frame, the characteristic information of each block is held in the immediately preceding significant frame characteristic information holding means,
When detecting the difference from the next captured frame, the feature information of each block held in the immediately preceding significant frame feature information holding means is used, so that the difference between frames can be calculated at high speed. Can be detected.

Further, according to the present invention, when the characteristic information of each block is calculated, only the information about a predetermined part of pixels in each block is used.
The feature information of the block can be calculated at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing example of the embodiment.

FIG. 3 is a diagram for explaining how blocks are made into frames.

FIG. 4 is a diagram illustrating an example of a method of calculating an average value of pixels in a block.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Moving image capture device 11 ... Frame capture means 12 ... Frame memory 13 ... File device 14 ... Capture control device 15 ... Interframe difference detection means 16 ... Significant frame determination means 17 ... Immediately significant frame feature information holding means 2 ... Video output apparatus

Claims (5)

(57) [Claims] 1. A frame capturing means for capturing a moving image frame by frame, a file device for storing a frame of the moving image, a frame last stored in the file device and a frame captured by the frame capturing means. An inter-frame difference detecting means for detecting a difference, and a significance determining whether or not the fetched frame is a significant frame to be stored in the file device, based on the difference detected by the inter-frame difference detecting means. An image capturing device comprising: a frame determining unit; and a capture control device that stores only a frame determined to be a significant frame by the significant frame determining unit in the file device. 2. The inter-frame difference detecting means divides the frame last stored in the file device and the frame captured by the frame capturing means into a plurality of blocks, and the difference between corresponding blocks. Is detected as the difference between the frames, and the significant frame determination means is configured to detect the difference between the blocks detected by the inter-frame difference detection means, if there is at least one difference exceeding the threshold, 2. The frame is determined to be a significant frame to be stored in the file device.
The image capturing device described. 3. An immediately preceding significant frame characteristic information holding unit is provided, and the inter-frame difference detecting unit is provided for each block of the significant frames last stored in the file device held in the immediately preceding significant frame characteristic information holding unit. The difference between corresponding blocks based on the feature information of each block and the feature information of each block of the frame captured by the frame capturing unit, and the frame captured by the frame capturing unit by the significant frame determining unit is significant. 3. The image capturing apparatus according to claim 2, wherein the characteristic information of each block of the frame captured by the frame capturing means is stored in the immediately preceding significant frame characteristic information holding means when it is determined to be a frame. 4. The inter-frame difference detection means calculates the characteristic information of each block by using only the information of a part of pixels determined in advance in each block. 3. The image capturing device described in 3. 5. The image capturing device according to claim 4, wherein the characteristic information is an average value of luminance of pixels in a block.