JP2002092614A - Device and method for processing image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of operation and to increase processing speed in carrying out correlative processing. SOLUTION: Using the property in which a correlation value falls in the shape of a concentric circle as it separates from the picture element position of the maximum correlation value in a prescribed search range, image data in first inputted successively to frame memories 11, 12 to delay almost frame by frame. In an arithmetic unit 13, the center picture element position of a search range where maximum correlation value picture elements exist with the highest probability from the respective output frames of the frame memories 11, 12 is set as an origin, and the correlation values are obtained every picture element on the origin and eight picture elements on the circumference. In the case of determining that the correlation values of eight picture elements on the circumference are larger than the correlation value of the origin, the origin is moved into the position of the picture element of the maximum correlation value out of eight picture elements to obtain the correlation values of eight picture elements around the origin successively on every picture element. This operation is repeatedly executed until the origin becomes immobile. When the origin becomes immobile, the origin is determined as the picture element position of the maximum correlation value in the search range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and an image processing method for extracting, searching, or detecting a motion image of a specific shape within a predetermined search range from image data by executing a correlation process between frames. Regarding the processing method.

[0002]

2. Description of the Related Art As is well known, for example, a video camera for field monitoring is provided with an image processing device for processing image data including a captured target object. This type of image processing apparatus performs any one of image extraction, search, and motion image detection of a specific shape within a predetermined search range from image data having a frame structure using, for example, a template matching processing method.

In the above-described image processing apparatus, it is necessary to search for a pixel position having a maximum correlation value from a predetermined search range when performing image extraction, search, or motion image detection of a specific shape. In order to search for the pixel position having the maximum correlation value, the correlation values of all the pixel positions in the search range must be obtained. Therefore, the amount of calculation increases and the processing speed decreases depending on the size of the search range.

[0004]

As described above, in the conventional image processing apparatus, when searching for the maximum correlation value pixel position from a predetermined search range, the correlation values of all the pixel positions in the search range must be obtained. For this reason, there is a disadvantage that the amount of calculation is increased and the processing speed is reduced depending on the size of the search range.

Accordingly, an object of the present invention is to eliminate the need to find correlation values for all pixel positions in a search range when acquiring target information, thereby reducing the amount of calculation and increasing the processing speed. It is an object of the present invention to provide an image processing apparatus and an image processing method that can perform the above.

[0006]

An image processing apparatus according to the present invention performs correlation processing between frames on image data having a frame structure to obtain target information in a predetermined search range. A frame memory that receives image data and delays by approximately one frame, and a correlation value of a predetermined search range center position pixel of both frames before and after the delay by the frame memory and a plurality of pixels around the frame is calculated for each pixel. A correlation calculating means for moving a starting point to a pixel position corresponding to a maximum correlation value among the obtained correlation values, and sequentially obtaining correlation values of a plurality of pixels around the pixel position for each pixel; And a maximum correlation position determining means for determining a pixel position of a final maximum correlation value within a predetermined search range.

The maximum correlation position determination means determines the pixel position at that time as the pixel position of the maximum correlation value within a predetermined search range when the starting point does not change by the correlation calculation means.

That is, in the present invention, image data is first input to a frame memory by taking advantage of the fact that the correlation value decreases concentrically as the position becomes farther from the pixel position of the maximum correlation value within a predetermined search range. One frame is delayed, and from both frames before and after the delay by the frame memory, the center pixel position of the search range where the maximum correlation value pixel exists with the highest probability is set as a starting point. Ask. Here, when it is determined that the correlation value of the peripheral pixel position is larger than the correlation value of the starting point, the starting point is moved to the pixel position of the maximum correlation value, and the correlation values of a plurality of pixels around the starting point are sequentially obtained for each pixel. This operation is repeatedly executed until the starting point does not move, and when the starting point does not move, the starting point is determined as the pixel position of the final maximum correlation value in the search range.

Therefore, according to the present invention, when acquiring the target information, it is not necessary to always calculate the correlation value for all the pixel positions in the search range, and the time when the starting point does not move is determined by the pixel position of the maximum correlation value. Therefore, the calculation amount can be reduced and the processing speed can be increased depending on the target shape, size, and moving speed.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of an image processing apparatus according to the present invention.

The image processing apparatus shown in FIG. 1 includes frame memories 11 and 12 and an arithmetic unit 13. The frame memory 11 outputs the input image data including the target object from the video camera, for example, with a delay of approximately one frame time. The frame memory 12 outputs the output of the frame memory 11 with a delay of approximately one frame time. The outputs of the frame memories 11 and 12 are supplied to the arithmetic unit 13, respectively.

The calculating device 13 includes a correlation calculating means 131,
And a maximum correlation position determining means 132. The correlation calculating means 131 obtains, for each pixel, the correlation value of the pixel at the center position of the predetermined search range and its surrounding eight pixels between the output frames of the frame memories 11 and 12, and sets the maximum correlation value among the obtained correlation values. The starting point is moved to a corresponding pixel position, and correlation values of eight pixels around the starting point are sequentially obtained for each pixel. That is, the correlation values are sequentially obtained by the template matching processing method.

The maximum correlation position determination means 132 determines the pixel position of the final maximum correlation value within a predetermined search range based on the processing result of the correlation calculation means 131.
Specifically, when the starting point does not change, the pixel position at that point is determined as the pixel position of the final maximum correlation value in the search range.

Next, the operation of the above configuration will be described. Each output of the frame memories 11 and 12 is
The arithmetic unit 13 starts a control process as shown in FIG.

When this control process is started, the arithmetic unit 13
First, the center position of the search range between frames is set as a starting point, and a correlation value of a pixel serving as the starting point is obtained (step ST1). Subsequently, the arithmetic unit 13 calculates a correlation value of eight pixels near the center position for each pixel (step ST2).
It is determined whether each correlation value of the pixel is larger than the correlation value of the pixel at the center position (step ST3).

Here, when it is determined that the value is large, (YE
S), the arithmetic unit 13 moves the starting point to the pixel position of the maximum correlation value among the eight pixels (step ST4), and repeatedly executes the processing of steps ST2 to ST4 until the starting point stops moving. However, the correlation value of the pixel position once obtained is not calculated again.

The arithmetic unit 13 then proceeds to step ST3.
When it is determined that the correlation value of the starting point is larger than the correlation value of the neighboring eight pixels (NO), the pixel position of this starting point is determined as the pixel position of the maximum correlation value within the search range (step ST5), and the processing is performed. finish.

In the above processing, as shown in FIG. 3, the correlation value decreases concentrically as the position becomes farther from the maximum correlation value pixel position. Therefore, in this embodiment, by utilizing this property, the center pixel position of the search range where the maximum correlation value pixel exists with the highest probability is set as the starting point, and the correlation value between this starting point and the eight surrounding pixels is sequentially obtained for each pixel. By going
The amount of calculation is reduced and the processing speed is increased.

As described above, in this embodiment, first, utilizing the property that the correlation value decreases concentrically as the distance from the pixel position of the maximum correlation value is increased within a predetermined search range, firstly,
The image data is sequentially input to the frame memories 11 and 12 and is delayed by approximately one frame. In the arithmetic unit 13, the search range in which the maximum correlation value pixel exists with the highest probability from each output frame of the frame memories 11 and 12 is determined. The center pixel position is used as a starting point, and a correlation value is obtained for each pixel with respect to this starting point and eight surrounding pixels. Here, around 8
When it is determined that the correlation value of the pixel is larger than the correlation value of the starting point, the starting point is moved to the pixel position of the maximum correlation value of the eight pixels, and the correlation values of the eight pixels around the starting point are sequentially obtained for each pixel, This operation is repeatedly performed until the starting point does not move, and when the starting point does not move, the starting point is determined as the pixel position of the final maximum correlation value in the search range.

Therefore, when obtaining target information, that is, when performing any of image extraction, retrieval, and motion image detection of a specific shape obtained by a video camera, it is necessary to always obtain a correlation value for all pixel positions in the search range. Since the point at which the starting point no longer moves is determined as the pixel position of the maximum correlation value, the amount of calculation can be reduced compared to the conventional method depending on the target shape, size, and moving speed. In addition, the processing speed can be increased.

Further, in this embodiment, the correlation calculation processing is performed from the center position of the search range by utilizing the property that the correlation value decreases concentrically as the pixel position becomes farther from the pixel position of the maximum correlation value within the predetermined search range. Since it is performed, there is no need to prepare complicated hardware or software for increasing the processing speed. For this reason, it can be implemented with a simple configuration and an inexpensive device.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the correlation operation is performed by the template matching processing method. However, the present invention is not limited to this template matching processing method, and may be arbitrary. Also, an example in which the image processing apparatus of the present invention is applied to a video camera has been described. However, the present invention is not limited to the video camera and may be arbitrary. In addition, various modifications can be made without departing from the spirit of the present invention.

[0024]

As described in detail above, according to the present invention,
When acquiring target information, there is no need to obtain a correlation value for all pixel positions in the search range, whereby an image processing apparatus and an image processing method capable of reducing the amount of calculation and increasing the processing speed are provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an image processing apparatus according to the present invention.

FIG. 2 is a flowchart showing a processing operation procedure of the arithmetic unit shown in FIG. 1;

FIG. 3 is an exemplary view showing an example of a distribution of correlation values within a search range by a template matching processing method applied in the embodiment;

[Explanation of symbols]

 11, 12: frame memory, 13: arithmetic device, 131: correlation operation means, 132: maximum correlation position determination means.

Claims (6)

[Claims] 1. An image processing apparatus for acquiring target information in a predetermined search range by performing a correlation process between frames on image data having a frame structure, wherein the image data is input and delayed by approximately one frame. And a correlation value of a predetermined search range center pixel of both frames before and after the delay by the frame memory and a plurality of pixels surrounding the pixel are determined for each pixel, and correspond to the maximum correlation value among the determined correlation values. A correlation operation means for moving a starting point to a pixel position and sequentially obtaining a correlation value of a plurality of pixels around the pixel position for each pixel; a final maximum value within the predetermined search range based on a processing result by the correlation operation means; An image processing apparatus comprising: a maximum correlation position determining unit that determines a pixel position of a correlation value. 2. The image processing apparatus according to claim 1, wherein said correlation calculating means sequentially calculates a correlation value for each of a plurality of pixels by a template matching processing method. 3. The maximum correlation position determining means determines a pixel position at that time as a pixel position of a final maximum correlation value within the predetermined search range at a time when a starting point does not change by the correlation calculating means. The image processing apparatus according to claim 1, wherein: 4. An image processing method for acquiring target information in a predetermined search range by performing a correlation process between frames on image data having a frame structure, wherein the image data is input and delayed by approximately one frame. And a correlation value for each of a plurality of pixels around the center position pixel of the predetermined search range of the two frames before and after the delay due to the first step, and a maximum correlation value among the obtained correlation values. A second step of moving a starting point to a corresponding pixel position and sequentially obtaining a correlation value for each of a plurality of pixels around this pixel position; and a final step within the predetermined search range based on a processing result of the second step. And a third step of determining a pixel position of a maximum correlation value. 5. The image processing method according to claim 4, wherein in the second step, a correlation value for each of a plurality of pixels is sequentially obtained by a template matching processing method. 6. In the third step, when the starting point does not change in the second step, the pixel position at that time is determined as the pixel position of the final maximum correlation value within the predetermined search range. The image processing method according to claim 4, wherein: