JP4050554B2 - Image motion detection circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image motion detection circuit and an image motion detection method for detecting a motion amount of an entire image sequence such as a television signal.
[0002]
[Prior art]
As a prior art relating to a motion detection circuit for a television signal, for example, one described in Japanese Patent No. 2585544 is known. FIG. 4 is a block diagram showing the configuration of the motion detection circuit described in the above publication. As shown in FIG. 4, the motion detection circuit includes an input terminal 401, a frame memory 402, a subtractor 403, a motion information conversion circuit 404, an integration circuit 405, and an output terminal 406. The television signal input to the input terminal 401 is input to the frame memory 402. The subtraction circuit 403 calculates a difference between input and output of the frame memory 402, that is, a difference between frames. Subsequently, the motion information conversion circuit 404 converts the inter-frame difference signal into a signal representing motion. The integration circuit 405 integrates motion information over the past finite frame period of the same pixel or peripheral pixels. With the above operation, the conventional motion detection circuit can output motion information from the output terminal 406.
[0003]
[Problems to be solved by the invention]
However, since the conventional motion detection circuit is configured to integrate the motion information over a predetermined past period after converting the absolute value of the interframe difference into motion information, a still image and another still image When a so-called scene change occurs, a large inter-frame difference value is calculated. As a result, the motion of the entire image sequence is detected as a large motion, which leads to deterioration of motion detection accuracy.
[0004]
This problem is not a big problem when the integration period is long, but becomes a big problem as the integration period becomes shorter.
Further, since the integration period corresponds to the time required for motion detection, there is a demand for shortening the integration period from the viewpoint of memory reduction.
[0005]
Therefore, an object of the present invention is to provide an image motion detection circuit and an image motion detection method capable of accurately detecting motion even for an image sequence in which different still images are connected. .
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an image motion detection circuit comprising: a first extraction unit that extracts an inter-frame difference absolute value from an input image signal in units of frames; and N (N is a natural number of 4 or more) frames. The larger of the holding means for holding the absolute difference value, the one frame absolute difference value extracted by the first extracting means, and the N interframe difference absolute values held by the holding means To M (M is a natural number not less than 1 and not more than N / 4) second extracting means for extracting the frame difference absolute values, and the N + 1 frame difference absolute values are extracted from the extracted M And adding means for adding except for the absolute value of interframe difference.
[0007]
According to a second aspect of the present invention, there is provided an image motion detection circuit comprising: first extraction means for extracting an inter-frame difference absolute value from an input image signal in units of frames; and a horizontal adjacent pixel difference value in units of frames from an input image signal. A second extraction means for extracting a cumulative addition value of N, a calculation means for calculating a frame motion amount from the absolute difference value between frames and the cumulative addition value of the horizontal adjacent pixel difference values, and N (N is 4 or more) Natural number) holding means for holding the frame motion amount, one frame motion amount calculated by the calculating means, and N frame motion amounts held by the holding means, the larger M (M is a natural number greater than or equal to 1 and less than or equal to N / 4) third extraction means for extracting frame motion amounts for the number N, and frame motion amounts for the N + 1 pieces, Add, except And having a that adding means.
[0008]
According to a third aspect of the present invention, there is provided an image motion detection method comprising: a first extraction step of extracting an inter-frame difference absolute value from an input image signal in units of frames; and N (N is a natural number of 4 or more) The larger one of the holding step for holding the inter-frame difference absolute value, and the one inter-frame difference absolute value extracted in the first extraction step and the N inter-frame difference absolute values held in the holding step. To M (M is a natural number greater than or equal to 1 and less than or equal to N / 4) second frame extraction steps, and the N + 1 frame difference absolute values are extracted as M + 1. And an addition step of adding except for the absolute difference value between frames.
[0009]
According to a fourth aspect of the present invention, there is provided an image motion detection method comprising: a first extraction step for extracting an inter-frame difference absolute value in units of frames from an input image signal; and a horizontal adjacent pixel difference value in units of frames from the input image signal. A second extraction step of extracting a cumulative addition value of N, a calculation step of calculating a frame motion amount from the absolute difference value between frames and the cumulative addition value of the horizontal adjacent pixel difference values, and N (N is 4 or more) Of the holding step for holding the (natural number) frame motion amounts, the one frame motion amount calculated in the calculating step, and the N frame motion amounts held in the holding step, M (M Is a natural number greater than or equal to 1 and less than or equal to N / 4) a third extraction step of extracting frame motion amounts for N + 1 frames, and N + 1 frame motion amounts for the extracted M frame motion amounts. Except for the arm motion amount, and having an addition step of adding.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the image motion detection circuit of the present invention will be described below with reference to FIGS.
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration example of an image motion detection circuit 100 according to the first embodiment of the present invention. The image motion detection circuit 100 includes a frame memory 101 that delays an input image signal for one frame period, a subtractor 102 that calculates a level difference between frames of pixels existing in the same spatial position of the input image signal, and a subtractor 102 An absolute value conversion circuit 103 that calculates an absolute value of a level difference calculated for each pixel, and a cumulative addition circuit 104 that resets the cumulative addition result to 0 at the head of the frame and cumulatively adds the absolute value in units of frames to obtain a cumulative addition value. N registers 105 for holding cumulative addition values of N (N is a natural number of 4 or more) inter-frame difference absolute values in units of frames, one cumulative addition value output by the cumulative addition circuit 104, and N Of the N cumulative addition values held by the registers 105, the cumulative addition values for M (M is a natural number of 1 or more and N / 4 or less) from the largest are extracted at the beginning of the frame. That and a singular point extraction circuit 106. In the following description, the cumulative addition value refers to the cumulative addition value of the interframe difference absolute value unless otherwise specified. In the image motion detection circuit 100, the singular point extraction circuit 106 extracts one cumulative addition value output from the cumulative addition circuit 104 and N cumulative addition values held by the N registers 105. An integration circuit 107 and a subtractor 108 are provided as means for adding except for the M cumulative addition values. The integration circuit 107 adds one cumulative addition value output from the cumulative addition circuit 104 and N cumulative addition values held by the N registers 105 to obtain a total value. The subtracter 108 subtracts the M cumulative addition values extracted by the singular point extraction circuit 106 from the total value of the cumulative addition values obtained by the integration circuit 107.
[0011]
Since the smallest number of frames that can effectively recognize a scene change due to the connection of two image sequences is generally 6, N is preferably a natural number of 4 or more. Therefore, in the first embodiment, an example will be described in which the image motion detection circuit 100 includes four registers 105 (registers 105a to 105d) and detects a motion amount in a 6-frame period.
[0012]
The operation of the image motion detection circuit 100 configured as described above will be described in detail. First, an image signal is input. The input image signal is delayed by one frame period in the frame memory 101 and input to the subtractor 102. The subtractor 102 calculates a level difference between pixels existing at the same spatial position from the input image signal and the output of the frame memory 101. The absolute value conversion circuit 103 converts the pixel level difference value between frames calculated by the subtractor 102 into an absolute value. The cumulative addition circuit 104 cumulatively adds the absolute values in units of frames to calculate a cumulative addition value of interframe difference absolute values. Thereafter, the cumulative addition value calculated by the cumulative addition circuit 104 is sequentially shifted and held in units of frames by four registers 105a to 105d connected in series. As a result of the above operation, the four cumulative addition values held in the registers 105a to 105d and the one cumulative addition value output from the cumulative addition circuit 104 are both singularity extraction circuit 106 and integration circuit. 107 is input.
[0013]
The singular point extraction circuit 106 extracts M cumulative addition values from the larger one of the five input cumulative addition values. When considering scene changes due to the connection of two image sequences over N + 1 frame periods, it is effective that the value of M is a natural number of 1 or more and N / 4 or less. In this case, the value of M is 1. Therefore, the singular point extraction circuit 106 extracts the maximum value among the five cumulative addition values. In this case, for example, in an image sequence in which still images are connected, only the cumulative addition value of the absolute value of inter-frame difference at the time of a scene change, in which different still images are continuous, becomes a very large value. Therefore, the extracted maximum value corresponds to the cumulative added value of the inter-frame difference absolute value at the time of the scene change. On the other hand, the integration circuit 107 calculates the total value of the five cumulative addition values.
[0014]
The maximum value extracted by the singular point extraction circuit 106 and the total value calculated by the integration circuit 107 are input to the subtractor 108. The subtracter 108 subtracts the maximum value from the total value of the five cumulative addition values. Thereby, the total value of the four cumulative addition values excluding the maximum value is calculated. The image motion detection circuit 100 outputs this total value as the motion amount of the entire image sequence.
[0015]
As described above, in the image motion detection circuit 100, when obtaining the motion amount for the 6 frame period, the cumulative addition value of the interframe difference absolute values for the 6 frame period is added except for the maximum value, and the motion of the entire image sequence is performed. Since the amount is detected, when the amount of motion is obtained for an image sequence in which still images are connected to each other, the amount of motion ignoring the scene change portion can be detected. Note that in an image sequence in which similar movements such as a sequence of still images or a sequence of moving images continue, an image that is detected even if one value is ignored among the cumulative addition values of a plurality of absolute differences between frames. There is no effect on the amount of movement of the entire sequence.
[0016]
An image motion detection method performed using the image motion detection circuit 100 according to the first embodiment will be described with reference to FIG. First, each data of the register 105, the cumulative addition circuit 104, and the frame memory 101 is initialized to 0 (step S301). The cumulative addition values held in the registers 105a to 105d in FIG. 1 are frame1, frame2, frame3, and frame4 in order from the register 105a, respectively, and the cumulative addition values held in units of frames by the cumulative addition circuit 104. Will be described below as frame0.
[0017]
Next, the image signal is input in units of frames, and the frame head of the input image signal is determined (step S302). If the result of the determination is not the head of the frame, an inter-frame difference that is a difference value between the level of the pixels constituting one frame of the input image signal and the pixel level of the image signal delayed by one frame period in the frame memory 101 The value is calculated by the subtractor 102, and the difference value is converted to an absolute value by the absolute value conversion circuit 103, thereby calculating an inter-frame difference absolute value (pixel_abs_diff) (step S307). This pixel_abs_diff is constantly calculated for pixels for one frame period. Then, the cumulative addition circuit 104 cumulatively adds pixel_abs_diff to calculate the cumulative addition value (frame_abs_diff) of the inter-frame difference absolute value (step S308). The frame_abs_diff is used when the cumulative addition circuit 104 performs cumulative addition of pixel_abs_diff over one frame period.
[0018]
On the other hand, if the result of determination in step S302 is the head of the frame, frame_abs_diff calculated by the cumulative addition circuit 104 is held as frame 0 in units of frames. Further, the registers 105a to 105d sequentially shift and hold the accumulated addition value held in units of frames. That is, by this shift operation, frame 0 held in frame units is substituted into frame 1, frame 1 into frame 2, frame 2 into frame 3, and frame 3 into frame 4 (step S303).
[0019]
Next, the maximum value (frame_max) among the cumulative addition values of the interframe difference absolute values held as frame0 in the cumulative addition circuit 104 and as frames1, frame2, frame3, and frame4 in the registers 105a to 105d is a singular point extraction circuit. Extraction is performed at 106 (step S304). Then, the total value of the five cumulative addition values (frame 0 to frame 4) is obtained by the integration circuit 107, and the maximum value extracted by the singular point extraction circuit 106 is subtracted by the subtracter 108 from the total value obtained by the integration circuit 107. Thus, the motion amount of the entire image is detected (step S305). Finally, frame_abs_diff, which is constantly used for calculation for cumulative addition of interframe difference absolute values, is reset to zero.
[0020]
As described above, according to the image motion detection circuit or the image motion detection method according to the first embodiment, the maximum value is extracted from the interframe difference absolute values for a predetermined frame period of the input image signal, Since the absolute value of inter-frame difference for a predetermined frame period is added excluding the maximum value and the motion of the entire image sequence is detected, the entire image sequence is excluded except for the unique value calculated at the time of a scene change. The motion detection accuracy of the image can be improved.
[0021]
In the first embodiment, when detecting the motion amount in the 6-frame period, the cumulative addition value of the five inter-frame difference absolute values is added excluding the maximum value, and the total value is added to the entire image sequence. Although the case of detecting as a motion amount has been described, in the case of a system in which the detection delay can be further increased, the image motion detection circuit 100 detects the motion amount of the entire image sequence using a larger cumulative addition value. can do. If this detection delay can be lengthened, the number of scene changes increases. Therefore, instead of removing only the maximum value, it is necessary to remove some values from the larger one and detect the motion amount. For example, in the case of detecting the motion amount of the entire image sequence using the cumulative addition value of the 10 interframe difference absolute values, the entire image sequence is obtained by removing the cumulative addition value of the two from the larger one It is detected as the amount of movement. In this case, the image motion detection circuit 100 shown in FIG. 1 includes nine registers 105, and the singular point extraction circuit 106 adds the largest two of the accumulated addition values of the 10 interframe difference absolute values. The cumulative addition value is extracted, and the integration circuit 107 calculates the total value of the cumulative addition values of the 10 interframe difference absolute values. Then, the subtractor 108 subtracts the extracted total value of the two cumulative addition values from the total value of the ten cumulative addition values to detect the motion amount of the entire image sequence.
[0022]
(Embodiment 2)
FIG. 2 is a block diagram showing a configuration of an image motion detection circuit 200 according to the second embodiment of the present invention. The same components as those in the image motion detection circuit 100 shown in FIG. In the second embodiment, as in the first embodiment, the case where the image motion detection circuit 200 includes four registers 105 (registers 105a to 105d) and detects the amount of motion in a six-frame period is described as an example. Do.
[0023]
The image motion detection circuit 200 according to the second embodiment is different from the image motion detection circuit 100 in that it includes a horizontal adjacent pixel difference calculation circuit 201 and a frame motion amount calculation circuit 202 as shown in FIG. The horizontal adjacent pixel difference calculation circuit 201 cumulatively adds the horizontal adjacent pixel differences of the input image signal in units of frames to obtain a cumulative added value (H). The frame motion amount calculation circuit 202 corrects the cumulative addition value (F) of the interframe difference absolute value by the cumulative addition value (H), and calculates the frame motion amount.
[0024]
The operation of the image motion detection circuit 200 according to the second embodiment will be described in detail. First, an image signal is input. The input image signal is delayed by one frame period in the frame memory 101 and input to the subtractor 102. The subtractor 102 calculates a level difference between pixels existing at the same spatial position from the input image signal and the output of the frame memory 101. The absolute value conversion circuit 103 converts the pixel level difference value between frames calculated by the subtractor 102 into an absolute value. The cumulative addition circuit 104 cumulatively adds the absolute values in units of frames to obtain a cumulative addition value (F) of interframe difference absolute values. The horizontal adjacent pixel difference calculation circuit 201 calculates a horizontal adjacent pixel difference from the input image signal of each frame, and cumulatively adds the difference for each frame to calculate a cumulative added value (H).
[0025]
The frame motion amount calculation circuit 202 receives the cumulative addition value (F) and the cumulative addition value (H), and calculates the motion amount in units of frames. This calculation can be performed, for example, by obtaining a ratio of F and H such as F / H (where H is other than 0). As a result, when an image having a high spatial frequency (that is, H is large) moves even a little, the value of F becomes very large, whereas an image having a low spatial frequency (that is, H is small). In this case, it is possible to correct the decrease in the value of F even if the movement is the same.
[0026]
The frame-by-frame motion amount calculated by the frame motion amount calculation circuit 202 is sequentially shifted and held by the registers 105a to 105d connected in series. As a result of the operation as described above, the four frame motion amounts held in the registers 105a to 105d and the one frame motion amount output from the cumulative addition circuit 104 are the singular point extraction circuit 106 and the integration circuit 107. Is input.
[0027]
The singular point extraction circuit 106 extracts M cumulative addition values from the larger one of the five input cumulative addition values. When considering scene changes due to the connection of two image sequences over N + 1 frame periods, it is effective that the value of M is a natural number of 1 or more and N / 4 or less. In this case, the value of M is 1. In this case, for example, in an image sequence in which still images are connected, only a frame motion amount at the time of a so-called scene change in which different still images are continuous becomes a very large value. Therefore, the extracted maximum value corresponds to the frame motion amount at the time of scene change. On the other hand, the integration circuit 107 calculates the total value of the five input frame motion amounts.
[0028]
The maximum value extracted by the singular point extraction circuit 106 and the total value calculated by the integration circuit 107 are input to the subtractor 108. The subtracter 108 subtracts the maximum value from the total value of the five frame motion amounts. Thereby, the total value of the four frame motion amounts excluding the maximum value among the five frame motion amounts is calculated. The image motion detection circuit 200 outputs this total value as the motion amount of the entire image sequence.
[0029]
Next, an image motion detection method performed using the image motion detection circuit 200 according to the second embodiment will be described with reference to FIG. This image motion detection method differs from the image motion detection method described in the first embodiment in the following points. First, processing is different when it is determined in step S302 shown in FIG. That is, while performing the processing of step S307, the horizontal adjacent pixel difference calculation circuit 201 calculates the cumulative addition value of the horizontal adjacent pixel differences of the input image signal, and the frame motion amount calculation circuit 202 calculates the frame_abs_diff calculated in step S308 and the horizontal adjacent pixel difference The frame motion amount is obtained from the cumulative addition value of the pixel differences. The difference is that the processing in steps S303 to S306 described in the first embodiment is performed on the frame motion amount.
[0030]
As described above, according to the image motion detection circuit or the image motion detection method according to the second embodiment, the input image signal includes the absolute value between frames and the cumulative addition value of horizontal adjacent pixel differences in units of frames. Extracts the amount of motion per frame, extracts the maximum value of the frame motion amount for a predetermined frame period, and adds the frame motion amount for a predetermined frame period, excluding the maximum value, to obtain the entire image sequence Therefore, the motion of the entire image sequence can be detected except for a unique value calculated at the time of a scene change, and the motion detection accuracy of the image can be improved.
[0031]
In the second embodiment, when detecting the motion amount in the 6-frame period, the five frame motion amounts are added excluding the maximum value, and the total value is detected as the motion amount of the entire image sequence. However, in the case of a system in which the detection delay can be further increased, the image motion detection circuit 200 can detect the motion amount of the entire image sequence using a larger amount of frame motion. If this detection delay can be lengthened, the number of scene changes increases. Therefore, instead of removing only the maximum value, it is necessary to remove some values from the larger one and detect the motion amount. For example, when the motion amount of the entire image sequence is detected using 10 frame motion amounts, the motion amount of the entire image sequence is detected by removing two values from the larger frame motion amount. In this case, the image motion detection circuit 200 shown in FIG. 2 includes nine registers 105, and the singular point extraction circuit 106 extracts the frame motion amount for the two largest ones out of the ten frame motion amounts. Then, the integration circuit 107 calculates the total value of the 10 frame motion amounts. Then, the subtracter 108 detects the motion amount of the entire image sequence by subtracting the total value of the two extracted frame motion amounts from the total value of the 10 frame motion amounts.
[0032]
【The invention's effect】
As described above, according to the present invention, the absolute value of interframe difference for a predetermined frame period of the input image signal is added to the entire image sequence by adding the absolute value of interframe difference for a predetermined number from the larger one. Therefore, even in an image sequence in which different still images are connected to each other, it is possible to detect the motion of the image sequence by ignoring the connection point. The effect that the whole motion detection accuracy can be improved is obtained. In particular, when it is necessary to shorten the period required for motion detection of an image sequence, the effectiveness is very large.
[0033]
Further, according to the present invention, the amount of motion in units of frames is calculated from the absolute value of inter-frame differences of the input image signal and the cumulative added value of horizontal adjacent pixel differences in units of frames, and the amount of frame motion for a predetermined frame period is calculated. Since the motion of the entire image sequence is detected by adding the frame motion amount of a predetermined number from the larger one, the motion amount that does not depend on the spatial frequency is calculated for each frame, and Even in an image sequence in which different still images are connected, the motion of the image sequence can be detected ignoring the connection point, thereby improving the motion detection accuracy of the entire image sequence The effect of being able to be obtained. In particular, when it is necessary to shorten the period required for motion detection of an image sequence, the effectiveness is very large.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image motion detection circuit according to a first embodiment of the present invention;
FIG. 2 is a block diagram showing a configuration of an image motion detection circuit according to a second embodiment of the present invention;
FIG. 3 is a flowchart for explaining an image motion detection method according to the first exemplary embodiment of the present invention;
FIG. 4 is a block diagram showing a configuration of a conventional motion detection circuit.
[Explanation of symbols]
100, 200 Image motion detection circuit 101 Frame memory 102, 108 Subtractor 103 Absolute value conversion circuit 104 Cumulative addition circuit 105 Register 106 Singular point extraction circuit 107 Integration circuit 201 Horizontal adjacent pixel difference calculation circuit 202 Frame motion amount calculation circuit

Claims (4)

First extraction means for extracting an inter-frame difference absolute value from the input image signal in units of frames;
Holding means for holding N (N is a natural number of 4 or more) pieces of inter-frame difference absolute values;
Of the one frame absolute difference value extracted by the first extracting means and the N interframe difference absolute values held by the holding means, M (M is 1 or more, N / A second extraction means for extracting the absolute value of interframe difference for a natural number of 4 or less);
An image motion detection circuit comprising: addition means for adding the N + 1 frame difference absolute values excluding the extracted M frame difference absolute values. First extraction means for extracting an inter-frame difference absolute value from the input image signal in units of frames;
Second extraction means for extracting a cumulative addition value of horizontal adjacent pixel difference values in units of frames from the input image signal;
Calculating means for calculating a frame motion amount from the inter-frame difference absolute value and the cumulative addition value of the horizontal adjacent pixel difference values;
Holding means for holding N (N is a natural number of 4 or more) frame motion amounts;
Of the one frame motion amount calculated by the calculating means and the N frame motion amounts held by the holding means, the largest M (M is a natural number of 1 or more and N / 4 or less). Third extraction means for extracting the frame motion amount of
An image motion detection circuit, comprising: addition means for adding the N + 1 frame motion amounts excluding the extracted M frame motion amounts. A first extraction step of extracting an inter-frame difference absolute value from the input image signal in units of frames;
A holding step of holding N (N is a natural number of 4 or more) pieces of the inter-frame difference absolute values;
Of the one frame absolute difference value extracted in the first extraction step and the N interframe difference absolute values held in the holding step, the largest one is M (M is 1 or more and N / 4 or less). A second extraction step of extracting the absolute value of the interframe difference for the natural number),
An image motion detection method comprising: an adding step of adding the N + 1 frame difference absolute values excluding the extracted M frame difference absolute values. A first extraction step of extracting an inter-frame difference absolute value from the input image signal in units of frames;
A second extraction step of extracting a cumulative addition value of horizontal adjacent pixel difference values for each frame from the input image signal;
A calculation step of calculating a frame motion amount from the inter-frame difference absolute value and the cumulative addition value of the horizontal adjacent pixel difference values;
A holding step for holding N (N is a natural number of 4 or more) pieces of the frame motion amount;
Of the one frame motion amount calculated in the calculation step and the N frame motion amounts held in the holding step, the largest M frames (M is a natural number of 1 or more and N / 4 or less). A third extraction step for extracting the amount of movement;
An image motion detection method comprising: an adding step of adding the N + 1 frame motion amounts excluding the extracted M frame motion amounts.

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