JP2005204025A - Circuit and method for movement detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit and method for movement detection capable of stably obtaining movement information, even if the frame difference information is not stable near a threshold and varies, when movement of pixels is sought. <P>SOLUTION: The movement detecting circuit is equipped with 1st and 2nd threshold filter circuits 2033 and 2034 which decide the movement information by pixels, based on the inter-frame difference information of image information according to previously set 1st and 2nd thresholds, a field movement information storing part 2038 which stores, for a single frame period, movement information generated by either of the 1st and 2nd threshold filter circuits 2033 and 2034, and a movement information selection part 2035, which compares 1st and 2nd pieces of movement information generated by the 1st and 2nd threshold filter circuits 2033 and 2034 with the movement information stored in the field movement information storing part 2038 to select and output one of the 1st and 2nd pieces of movement information. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motion detection circuit and a motion detection method for determining the movement of each pixel constituting video information when, for example, converting video information by interlaced scanning into video information by sequential scanning.

  In recent years, as a method of television broadcasting, the study from the conventional analog method to the digital method has started, and as a result of the new technological innovation of digitalization, television broadcasting has become more advanced as an information communication medium, and has made dramatic progress Is trying to achieve.

In order to cope with such digital television broadcasts, television broadcast receivers have also evolved, and a thin, large-screen plasma display has appeared, and conventional CRT-type television receivers are also digital televisions. Some of them have high-definition resolution for broadcasting. In these image display devices, video display by sequential scanning is performed instead of conventional video display by interlaced scanning for each line. Therefore, when displaying a conventional analog television broadcast, video information obtained by interlaced scanning is converted into video information obtained by sequential scanning (hereinafter referred to as IP (Interlace-Progressive) conversion), and the resolution of the display device is further increased. The video information is converted and displayed.

  Here, a conventional IP conversion processing circuit will be briefly described. FIG. 3 is a block diagram showing a configuration of a general IP conversion processing circuit.

  In FIG. 3, reference numerals 101 and 102 denote two field information storage units for storing input video information in units of fields.

  Reference numeral 103 denotes a difference between the input field information and the field information output from the field information storage unit (2) 102 and input in the past one frame period from the input field information. Is a motion information generation unit that determines whether the information is moving image information or still image information in pixel units, and further determines and outputs the motion at the interpolated pixel from the motion information obtained for each pixel.

  104 is a line information storage unit for storing input video information in units of lines, 107 is an adder that performs addition operation of two input signals, and 108 is added by the adder 107. A divider 109 for obtaining a half value of the obtained value is one field period longer than the input field information output from the field information storage unit (1) 101 in response to the output signal from the motion information generation unit 103. This is an interpolation information selection unit that selects either the pixel information input in the past or the average value of the pixel values in the upper and lower lines of the interpolation pixel position, which is output from the divider 108, and sets it as the interpolation pixel value.

  Reference numerals 105 and 106 each store pixel information output from the interpolation information selection unit 109 and input pixel information in units of lines, and read out the stored pixel information at twice the speed of the input video information. The two input / output speed conversion units 110 are display information selection units that switch the pixel information output from the input / output speed conversion unit (1) 105 and the input / output speed conversion unit (2) 106 for each line. is there.

  The operation of the conventional IP conversion processing circuit described above will be described below.

  The input video information by the jump operation is input to the field information storage unit (1) 101 and the line information storage unit 104, and pixel information delayed by one field period and pixel information of one line before can be obtained from each.

Here, the NTSC (national television system) displayed by interlaced scanning is shown in FIG.
The video information in the committee) signal is shown. In the NTSC signal, as shown in FIG. 4A, one screen is composed of 525 horizontal lines, and the unit of one screen is called a frame. Further, the frame is divided into an odd field representing an odd line shown in FIG. 4B and an even field representing an even line shown in FIG. 4C by interlaced scanning. The video information of 525 lines is expressed by alternately displaying the video. That is, the odd field and the even field are in a relationship of interpolating the line information that is lacking.

  Therefore, returning to FIG. 3 again, the field information storage unit (1) 101 obtains image information in the previous field corresponding to the position of the pixel to be interpolated, and stores the input video information and line information. From the unit 104, pixel information on the upper and lower lines of the pixel to be interpolated is obtained. Further, from the input video information and the line information storage unit 104, an average value of pixel information in the upper and lower lines of the pixel to be interpolated is obtained by the adder 107 and the divider 108, and is used as interpolation pixel information at the time of moving image. It is done.

  The pixel information output from the field information storage unit (1) 101 is further delayed by one field period by the field information storage unit (2) 102 and is video information delayed by one frame period from the input video information, that is, Pixel information in the previous frame corresponding to the position of the input pixel is obtained.

  The motion information generation unit 103 determines the motion for each pixel of the input video information from the input video information and the video information delayed by one frame period output from the field information storage unit (2) 102, and The motion at the pixel to be interpolated is determined from the motion information for each pixel of the input video information and output as motion information at the interpolated pixel.

  When the motion information output from the motion information generation unit 103 is “0”, the interpolation information selection unit 109 determines that the pixel information output from the field information storage unit (1) 101 is “1”. Selects pixel information output from the divider 108 and outputs it as interpolated pixel information.

  The input / output speed conversion unit (1) 105 and the input / output speed conversion unit (2) 106 each store the interpolation pixel information output from the interpolation information selection unit 109 and the input video information in units of lines. The pixel information is read out at twice the speed of the input video information, and the display information selection unit 110 outputs the pixel information and the input / output speed conversion unit from the input / output speed conversion unit (1) 105 for each line. (2) The pixel information output from 106 is switched and output.

  Next, the motion information generation unit 103 will be described. FIG. 5 is a block diagram illustrating an example of the motion information generation unit 103.

  In FIG. 5, reference numeral 1031 denotes the field information that is currently input and the field information that is output from the field information storage unit (2) 102 and that has been input one frame period before the currently input field information. It is a subtractor for obtaining a difference. Reference numeral 1032 denotes an absolute value unit for obtaining the absolute value of the difference value obtained by the subtracter 1031.

1033 compares the value obtained by the absolute value unit 1032 with a preset threshold value,
When the value obtained by the absolute value unit 1032 is smaller than the threshold value, it is determined that the pixel is a still image and “0” is output, and the value obtained by the absolute value unit 1032 is larger than the threshold value. Alternatively, in the case where they are equal, the threshold filter circuit determines that the pixel is a moving image and outputs “1”, so that even when incorrect pixel information such as noise is added to the input video information. If there are some fluctuations, the influence can be removed.

  Reference numeral 1034 denotes a line motion information storage unit for storing the motion information for each pixel output from the threshold filter circuit 1033 in units of lines, whereby the line motion information storage unit 1034 receives the input video information. It is possible to obtain motion information at a pixel one line before. 1035 is the motion information output from the threshold filter circuit 1033 and the motion information at the pixel one line before output from the line motion information storage unit 1034, and the motion information at the interpolated pixel generated between the lines. It is an interpolated pixel motion information generation unit that determines and outputs.

  According to the conventional motion information generation unit 103 described above, the input pixel information is first output from the field information storage unit (2) 102 in the subtractor 1031 by one frame from the input field information. The difference from the field information input in the past period is obtained, and then the difference information converted into a positive value by the absolute value unit 1032 is compared with the threshold value set in advance in the threshold filter circuit 1033, and the difference information is If it is smaller than the threshold, it is determined that the pixel is a still image, and if it is greater than or equal to the threshold, it is determined that the pixel is a moving image and is output as motion information at the input pixel. It will be.

  As described above, when determining the movement of each pixel constituting conventional video information, difference information between one frame is obtained, the obtained difference information is compared with a preset threshold value, and the difference information is a threshold value. If it is smaller than the threshold, it is determined that the pixel is a still image, and if it is greater than or equal to the threshold, it is determined that the pixel is a moving image.

  In such a conventional motion detection circuit, when the pixel value slightly changes due to external factors such as noise, and the difference information changes without being stabilized near the threshold value, a pixel that is originally a still image or a moving image The motion information at a certain pixel is frequently switched between a case where it is determined to be a still image and a case where it is determined to be a moving image, and as a result, pixel values at interpolated pixels located in the vicinity thereof frequently change. As a result, the image quality is significantly deteriorated.

In response to such a problem, the motion information is determined by comparing the size with a threshold value, and is not switched between a still image and a moving image in a switch manner. It is managed as information, and the pixel value at the interpolated pixel located in the vicinity according to the obtained motion information is obtained by mixing the interpolated pixel value in the case of a still image and the interpolated pixel value in the case of a moving image. For example, the following Patent Document 1 and Patent Document 2 disclose a technique of preventing the interpolated pixel value in the vicinity of the threshold value from changing abruptly.
Japanese Patent Laid-Open No. 01-194893 Japanese Patent Laid-Open No. 03-192980

  However, in the method disclosed in the above-described prior art, the pixel value at the interpolation pixel is obtained by mixing the interpolation pixel value in the case of a still image and the interpolation pixel value in the case of a moving image, which is originally a moving image. Motion information, which may be managed as 1-bit information indicating whether the image is a still image or not, must be managed as information of a plurality of bits. For example, when motion information is referenced over time, an increase in storage means is required. I will invite you.

In addition, it is possible to reduce the sudden change of the interpolated pixel value that occurs near the threshold by mixing the interpolated pixel value in the case of a still image and the interpolated pixel value in the case of a moving image. Thus, the influence of the interpolated pixel value in any one of the cases (moving image or still image) will appear as a display state, and the deterioration of the image quality cannot be completely eliminated.

  The present invention has been made in view of the above problems, and can manage motion information for each pixel constituting input video information as 1-bit information, and can stabilize difference information in the vicinity of a threshold value. A motion detection circuit and a motion detection method capable of avoiding frequent switching between a case where motion information is determined to be a still image and a case where motion information is determined to be a moving image The purpose is to provide.

  In order to achieve the above object, in the motion detection circuit of the present invention, based on the inter-frame difference information of the image information, the motion information for each pixel according to the first and second threshold values set in advance. A first and second motion information generation unit for determining the motion information, a motion information storage unit for storing motion information generated by one of the first and second motion information generation units for one frame period, and the motion The first and second movements are compared by comparing the movement information stored in the information storage unit with the first and second movement information generated by the first and second movement information generation units. And a motion information selection unit that selects and outputs any of the information.

  The motion detection method of the present invention is a motion detection method for detecting the motion of an image displayed on an image display device composed of a plurality of pixels, and sets a threshold based on inter-frame difference information of the image information. And a step of comparing the difference information between frames of the image information of the pixel with the threshold value to determine whether the image is a moving image or a still image, and the determination result of the determining step of the previous frame is the threshold value It is characterized by being set with hysteresis according to the above.

  The threshold is preferably set to a larger value when the determination result of the determination step of the previous frame is a still image than when the determination result of the previous frame is a moving image.

  According to the present invention, first and second thresholds having different values are provided in advance, and the first and second threshold values are referred to by referring to the past motion information for one frame period in the pixel for which motion information is to be obtained. Which one of the threshold values is to be used is determined, whereby it is possible to have a hysteresis effect in determining the motion information, and the motion information for each pixel can be managed as 1-bit information, and the difference information is Even in the case of changing without being stabilized near the threshold value, the motion information can be obtained stably.

  DETAILED DESCRIPTION Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  In addition, about the part demonstrated by background art, the same code | symbol is attached | subjected here and description is abbreviate | omitted.

  FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention in the motion information generation unit 103 included in the IP conversion processing circuit shown in FIG.

In FIG. 1, reference numeral 2031 indicates that the field information that is currently input and the field information storage unit (2) 102 illustrated in FIG. 3 that is input in the past for one frame period from the input field information. It is a subtractor that obtains a difference from field information. Reference numeral 2032 denotes an absolute value unit for obtaining the absolute value of the difference value obtained by the subtractor 2031.

  2033 and 2034 compare the value obtained by the absolute value unit 2032 with a preset threshold value. If the value obtained by the absolute value unit 2032 is smaller than the threshold value, the pixel is a still image. If the value obtained by the absolute value unit 2032 is greater than or equal to the threshold value, it is determined that the pixel is a moving image and “1” is output. It is a filter circuit.

  Reference numeral 2035 denotes a motion information selection unit that selects and outputs one of the pixel motion information output from the threshold filter circuit (1) 2033 and the threshold filter circuit (2) 2034. Reference numeral 2036 denotes a line motion information storage unit for storing motion information for each pixel output from the motion information selection unit 2035 in units of lines. Reference numerals 2037 and 2038 denote two field motion information storage units for storing motion information for each pixel output from the motion information selection unit 2035 in units of fields. Reference numeral 2039 denotes the motion information at the interpolation pixel generated between the motion information output from the motion information selection unit 2035 and the motion information at the pixel one line before output from the line motion information storage unit 2036. This is an interpolated pixel motion information generation unit that determines and outputs.

  Next, the operation of the motion information generation unit 103 according to the present invention having the configuration described above will be described.

  First, the input pixel information is output from the field information storage unit (2) 102 shown in FIG. 3 in the subtractor 2031 to the field information input in the past by one frame period from the input field information. The difference is obtained, converted into a positive value by the absolute value unit 2032 and output.

  The difference information output from the absolute value unit 2032 is input to the threshold filter circuit (1) 2033 and the threshold filter circuit (2) 2034, and is set in advance in the threshold filter circuit (1) 2033 and the threshold filter circuit (2) 2034. If the difference information is smaller than the threshold, the pixel is determined to be a still image, and “0” is determined. If the difference information is greater than or equal to the threshold, the pixel is It judges that it is a moving image, and outputs "1" as motion information. That is, motion information for each pixel is output as 1-bit information from the threshold filter circuit (1) 2033 and the threshold filter circuit (2) 2034.

  Here, different values are set for the threshold values preset in the threshold filter circuit (1) 2033 and the threshold filter circuit (2) 2034, respectively. In this example, the threshold value filter circuit (1) 2033 is set with the value of the threshold value (1) shown in FIG. 2, and the threshold value filter circuit (2) 2034 has a value larger than the threshold value (1). It is assumed that the threshold value (2) shown in FIG.

  In the motion information selection unit 2035, a threshold filter circuit (1) is output according to the motion information in the field input one frame period before the input field, which is output from the field motion information storage unit (2) 2038 described later. ) One of the motion information output from 2033 and the motion information output from the threshold filter circuit (2) 2034 is selected and output.

FIG. 2 shows how motion information is selected by the motion information selection unit 2035. In this example, in the motion information selection unit 2035, the field motion information storage unit (2) 20
The motion information output from the threshold filter circuit (2) 2034 is selected when the motion information in the field input in the past for one frame period output from 38 is a still image, and the threshold when it is a moving image. The motion information output from the filter circuit (1) 2033 is selected and output.

  That is, when the past state of the input pixel is a still image, the value of the threshold (2) set in the threshold filter circuit (2) 2034 and the difference information output from the absolute value unit 2032 are obtained. When the difference information is smaller than the threshold value (2), it is determined as a still image and “0” is output. When the difference information is larger than or equal to the threshold value (2), it is determined that the pixel is a moving image. As a result, “1” is output.

  When the past state of the input pixel is a moving image, the threshold value (1) set in the threshold filter circuit (1) 2033 is compared with the difference information output from the absolute value unit 2032; When the difference information is smaller than the threshold (1), it is determined as a still image and “0” is output. When the difference information is larger than or equal to the threshold (1), it is determined that the pixel is a moving image. 1 "is output.

  As a result, it is possible to give a hysteresis effect to the change between the motion information moving image and the still image. For example, the difference information at the pixel that was a still image in the past is larger than the threshold (2), and the change from the still image to the moving image is performed. In such a case, even if the difference information slightly changes after one frame period and becomes a value smaller than the threshold (2), if the difference information is larger than the threshold (1), This state is maintained.

  Also, if the difference information at the pixels that were moving images in the past is smaller than the threshold value (1) and changes from moving images to still images, the difference information slightly changes after one frame period and the threshold value ( Even if the value is larger than 1), if the difference information is smaller than the threshold value (2), the state as a still image is held.

  The pixel motion information output from the motion information selection unit 2035 is stored for one line in the line motion information storage unit 2036, and is output as motion information for the pixel one line before. The pixel motion information output from the motion information selection unit 2035 is simultaneously input to the field motion information storage unit (1) 2037, stored for one field, and further output from the field motion information storage unit (1) 2037. The motion information at the pixel one field before is further delayed by one field period by the field motion information storage unit (2) 2038. Delayed motion information is output.

  The interpolated pixel motion information generation unit 2039 generates between the lines based on the motion information output from the motion information selection unit 2035 and the motion information of the previous pixel output from the line motion information storage unit 2036. The motion information at the interpolation pixel is judged and output.

  The motion information at the interpolated pixel generated in this manner is obtained by using the conventional IP conversion processing circuit shown in FIG. It will be used to determine whether to output pixel information.

It is the block diagram which showed the structure of the motion information generation part as one Embodiment of this invention. It is the schematic diagram which showed a mode that the motion information was produced | generated in this invention. It is the block diagram which showed the structure of the IP conversion processing circuit. It is the schematic diagram which showed a mode that it displayed with the video information of an interlace scanning system. It is the block diagram which showed the structure of the conventional motion information generation part.

Explanation of symbols

101, 102 Field information storage unit 103 Motion information generation unit 104 Line information storage unit 105, 106 I / O speed conversion unit 107 Adder 108 Divider 109 Interpolation information selection unit 110 Display information selection unit 1031, 2031 Subtractor 1032, 2032 Absolute Value unit 1033, 2033, 2034 Threshold filter circuit 1034, 2036 Line motion information storage unit 1035, 2039 Interpolated pixel motion information generation unit 2035 Motion information selection unit 2037, 2038 Field motion information storage unit

Claims (3)

First and second motion information generation units for determining motion information for each pixel according to first and second threshold values set in advance based on inter-frame difference information of image information;
A motion information storage unit that stores motion information generated by one of the first and second motion information generation units for one frame period;
The first and second motion information stored in the motion information storage unit is compared with the first and second motion information generated by the first and second motion information generation units. A motion information selection unit that selects and outputs any of the motion information of
A motion detection circuit comprising: A motion detection method for detecting a motion of an image displayed on an image display device comprising a plurality of pixels,
Setting a threshold based on difference information between frames of image information;
Comparing inter-frame difference information of the image information of the pixel with the threshold value to determine whether the image is a moving image or a still image;
Have
The motion detection method, wherein the threshold is set with hysteresis according to a determination result of the determination step of the previous frame. The threshold value is set to a larger value when the determination result of the determination step of the previous frame is a still image than when the determination result of the previous frame is a moving image. The motion detection method described.

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