JPH0683436B2 - Motion vector detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a motion vector detecting method for detecting the amount of motion of a television signal applied to the field number conversion processing in the television format conversion, for example.

[Outline of Invention]

According to the present invention, a television signal is divided into a large number of detection areas, a representative point is set for each detection area, the absolute value of the difference between the corresponding representative point of two fields and each pixel in the detection area is calculated, and the difference In a representative point method motion vector detection method using so-called block matching, in which absolute values are aggregated and a minimum value is detected as a motion vector in the absolute value aggregated data, one of two vertically adjacent detection areas is detected. By displacing the position of the representative point and the position of the other representative point in the horizontal direction by a predetermined amount, it is possible to accurately detect the motion vector of a pattern such as a vertical stripe.

[Prior Art] As one method of detecting the motion of a television image, the television image is divided into a number of block-shaped detection areas, and matching determination between corresponding detection areas between the previous frame and the current frame is performed. A block matching method is known which detects a motion by performing the operation. Among the block matching methods, there is a representative point method that can simplify hardware and shorten processing time.

In the conventional representative point type motion vector detection method using block matching, as shown in FIG. 4, a detection area is defined like a grid and a central position of each detection area is used as a representative point. That is, the size of the detection area is (X pixels x Y lines)
Then, the representative point is set to the central position represented by (X × 2) and (Y × 2), and the line connecting the representative points is in a lattice shape as shown by a broken line. In the example shown in FIG. 4, the interval between the representative points in the horizontal direction is X.

[Problems to be solved by the invention]

In the conventional motion vector detection method, since the representative points of the respective detection areas are aligned in the vertical direction, there are cases where the spatial frequency such as fine vertical stripes is high and the movement of a naturally existing pattern cannot be detected. That is, a motion in which the position of the vertical stripe in the previous frame and the position in the current frame apparently match each other cannot be detected, and a malfunction occurs in which the motion vector becomes a zero vector.

Therefore, an object of the present invention is to provide a motion vector detection method capable of accurately detecting a motion vector even in the case of an image having a pattern such as fine vertical stripes.

[Means for solving problems]

According to the present invention, a two-dimensional detection area formed by a plurality of pixels in the same field and a representative point for each detection area are defined, and the representative point of one field of the corresponding two fields and the detection of the other field are detected. In the motion vector detection method, the difference between each pixel in the area is calculated, and the minimum value is detected in the absolute value total data in which the absolute value of the difference is totaled, and this minimum value is detected as the motion vector. Is a motion vector detecting method characterized in that the position of one representative point and the position of the other representative point of the two detection areas adjacent to are shifted in the horizontal direction by a predetermined amount.

[Action]

Since the representative points of the respective detection areas are not aligned in the vertical direction, it is possible to increase the effect of detecting the motion vector in the case of an image such as vertical stripes.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a representative point type motion vector detection circuit using block matching which can be used for implementing the present invention. The digital video signal from the input terminal 1 is supplied to the subtraction circuit 2 and the representative point selection circuit 3,
The selected representative point is stored in the representative point memory 4. The subtraction circuit 2 subtracts the representative point of the previous frame read from the representative point memory 4 and each pixel of the input current frame for each detection area. The frame difference data ΔF from the subtraction circuit 2 is converted into absolute value frame difference data | ΔF | by the conversion circuit 5. This data | ΔF | is the counting circuit 6
And all the data in one field | ΔF | are accumulated for each pixel in the detection area, and the frame difference total data Σ
| ΔF | is required. The minimum value detection circuit 7 detects the minimum value in the frame difference total data Σ | ΔF | and outputs the position of this minimum value to the output terminal 8 as a motion vector.

As an improved configuration of the motion vector detection circuit shown in FIG. 1, the position of the minimum point of the frame difference data ΔF in the detection area is obtained, and when the position of this minimum point is a small vector, the frame difference data ΔF is calculated. There is a configuration that is not a target of aggregation, or a frame difference between pixels is obtained, and when the frame difference is small, the frame difference data ΔF is not a subject of aggregation. These configurations can prevent the motion vector from becoming a zero vector due to a background with a sharp change. The present invention can be applied to the motion vector detecting circuit having these improved configurations.

In one embodiment of the present invention, as shown in FIG. 2, the position of one representative point and the position of the other representative point of two vertically adjacent detection areas are shifted by 1 / 2x in the horizontal direction. The representative point selection circuit 3 selects the position of the representative point. x is the horizontal distance between the representative points. A detection area of X pixels and Y lines is set around each representative point. By thus defining the representative points, the respective detection areas are arranged in a checkered pattern.

In the example shown in FIG. 2, the relationship is (X = x). However, the detection areas may be overlapped with each other in order to improve the detection capability. Also, one field is divided into four,
A motion vector may be detected for each of the divided regions, four motion vectors may be determined, and a motion vector for one field may be obtained.

As described above, according to the present invention, the positions of the representative points are not aligned in the vertical direction, so that it is possible to improve the ability to detect the movement of a pattern having a high spatial frequency such as vertical stripes.

INDUSTRIAL APPLICABILITY The present invention can be applied to the conversion of the number of fields when converting a high definition television system (1125 lines / 60 fields), a so-called HD system, to a PAL system (625 lines / 50 fields). FIG. 3 shows the overall configuration of this (HD → PAL) system converter.

In FIG. 3, the luminance signal in the high-definition television signal is supplied to the input terminal indicated by 11, and this luminance signal is supplied to the A / D converter 13 via the low-pass filter 12. A
Digital luminance signal from the A / D converter 13 is pre-processing circuit
Supplied to 14. The preprocessing circuit 14 performs conversion of the number of lines and deinterlacing.

The number of lines is converted from 1125 to 625 using, for example, the technique of digital frequency conversion. In addition, the sum of the number of lines is 62 from the video of one field of the high definition television signal.
Five first field images and second field images are simultaneously formed. This second field image is the first
The field image is offset by 0.5 lines. Therefore, the pre-processing circuit 14 obtains a digital video signal including only the first field of (625 lines / 60 frames) and a digital video signal including only the second field of (625 lines / 60 frames). The motion vector detection is performed using the video signal of the first field, and the conversion process of the number of fields is processed separately for each of the first field and the second field.
By performing the above-mentioned deinterlacing in the preprocessing circuit 14, the detection accuracy can be improved by detecting the motion vector every 1/60 seconds, and the interpolation signal can be easily formed.

Reference numeral 15 denotes a motion vector detecting circuit to which the present invention can be applied, and the motion vector detecting circuit 15 is supplied with the digital video signal of the first field. Also, a field number conversion circuit 21 for the first field and a field number conversion circuit 22 for the second field are provided, and the detected motion vector is the field number conversion circuit for these fields.
Supplied to 21 and 22.

The motion vector detection circuit 15 calculates the difference between the representative point of the previous field and the pixel of the current field (field difference data) for each detection area, totals the absolute values of this field difference data, and generates the field difference totalized data. However, the minimum value of the field difference aggregation data is detected. In the motion vector detection circuit 15, as described above, the positions of one representative point and the other representative point of the detection areas that are vertically adjacent to each other are shifted by a predetermined amount (x × 2).

In addition, from the field number conversion circuit 21, (625 lines / 50
The digital video signal of the first field of (frame) is output, and the digital video signal of the second field of (625 lines / 50 frame) is output from the field number conversion circuit 22. The output signals of the field number conversion circuits 21 and 22 are supplied to the switch circuit 31. Although not shown, the switch circuit 31 is supplied with a control signal that is inverted every 1/50 seconds, and a digital luminance signal of (625 lines / 50 fields) is taken out from the output of the switch circuit 31.

This digital luminance signal is supplied to the D / A converter 32. The output signal of the D / A converter 32 is the low-pass filter 33.
And is supplied to the PAL color encoder 34 via. Similarly to the luminance signal Y, the red color difference signal RY and the blue color difference signal BY subjected to the conversion of the number of lines and the conversion of the number of fields are supplied to the PAL color encoder 34. Therefore, a PAL composite color television signal can be obtained at the output terminal 35 of the PAL color encoder 34. To the output terminal 35, a PAL type color television receiver is connected.

The field number conversion circuit 21 is composed of a field memory 23, a motion correction circuit 24, a linear approximation circuit 25, a switch circuit 26, an error processing detection circuit 27, and a memory 28. The field number conversion circuit 22 has the same configuration as the field number conversion circuit 21.

Both the digital video signal of the previous field and the input digital video signal of the current field from the field memory 23 are supplied to the motion correction circuit 24, the linear approximation circuit 25, and the error processing detection circuit 27. One of the output signal of the motion correction circuit 24 and the output signal of the linear approximation circuit 25 is a switch circuit 26.
Selected by. The switch circuit 26 is an error detection circuit.
It is controlled by the detection output of 27, and the correction output on the side for which more correct processing is performed is selected. The erroneous processing detection circuit 27 is supplied with both the signal obtained by shifting the image of the previous field and the signal obtained by shifting the image of the current field formed in the motion correction circuit 24. Further, the memory 28 to which the output of the switch circuit 26 is supplied is for expanding the time axis.

The motion correction circuit 24 converts the continuous six images of the first field into five images, and uses the motion vector detected by the motion vector detection circuit 15 to perform image shift processing. By adding the motion, unlike the simple thinning process, the motion of the converted image does not become unnatural.

The linear approximation circuit 25 is an interpolation circuit that multiplies each of the images of two consecutive fields by a predetermined weighting coefficient and adds the multiplication outputs. The linear approximation circuit 25 has a problem that the image is doubled or blurred in the moving part, but in the stationary part, the linear approximation is better than the motion correction.

The erroneous processing detection circuit 27 determines the field difference ΔFL between the image in the previous field and the image in the current field, and the difference Δf between the image obtained by shifting the image in the previous field by a predetermined amount and the image obtained by shifting the image in the current field in the opposite direction by a predetermined amount. Is detected, the magnitudes of the difference signals ΔFL and Δf are compared with each other, and the comparison output is judged by majority in each detection region. In other words, (ΔFL>
The pixels having the relationship of Δf) are determined to be correct in the motion correction processing, and the pixels having the relationship of (ΔFL <Δf) are determined to be incorrect in the motion correction processing.
With respect to all the pixels in the detection area, it is determined which of the pixels has a large number of pixels. The switch circuit 26 is controlled by the result of this determination.

Further, the motion correction circuit 24 may be configured to use both an image obtained by shifting the image of the current field by a predetermined amount and an image obtained by shifting the image of the previous field in the opposite direction by a predetermined amount.

The present invention can be applied to a high-efficiency coding device, a motion compensating device of a high-definition television signal band compression transmission device, etc., in addition to the television signal format conversion device.

〔The invention's effect〕

According to the present invention, in the representative point type motion detection method using block matching, the positions of the representative points are not aligned in the vertical direction, and the representative point of one of the upper and lower detection areas and the other detection area Since the representative point is shifted by a predetermined amount in the horizontal direction, it is possible to accurately detect the movement of fine vertical stripes.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of a motion vector detection circuit that can be used for implementing the present invention, FIG. 2 is a schematic diagram used for explaining one embodiment of the present invention, and FIG. 3 is a system to which the present invention can be applied. FIG. 4 is a block diagram of the conversion device, and FIG. 4 is a schematic diagram used for explaining a conventional motion vector detecting method. Description of main symbols in the drawing 1: Input terminal, 2: Subtraction circuit, 3: Representative point selection circuit, 6: Aggregation circuit,
7: Minimum value detection circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Matsumoto 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Yutaka Tanaka 1-1-10 Kinuta, Setagaya-ku, Tokyo Japan (72) Inventor Toshiro Omura 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Broadcasting Research Institute of Japan Broadcasting Corporation (72) Inventor Taiichi Kurita 1-10-10 Kinuta, Setagaya-ku, Tokyo No. 11 Inside the Broadcasting Technology Research Institute of the Japan Broadcasting Corporation (72) Inventor Yoshimichi Otsuka 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Broadcasting Technology Research Institute of the Japan Broadcasting Corporation (72) Taiji Nishizawa Kinuta Setagaya-ku, Tokyo 1-10-11 Broadcasting Engineering Laboratory of Japan Broadcasting Corporation (72) Inventor Yuichi Ninomiya 1-10-11 Kinuta, Setagaya-ku, Tokyo Broadcasting Engineering Laboratory of Japan Broadcasting Association

Claims (1)

[Claims] 1. A two-dimensional detection area formed by a plurality of pixels in the same field and a representative point for each of the detection areas are defined, and the representative point of one field of the corresponding two fields and the other The difference between each pixel in the detection area of the field is calculated, and the minimum value is detected in the absolute value aggregate data in which the absolute value of the difference is aggregated, and this minimum value is detected as the motion vector Motion vector detection In the method, the position of the representative point of one of the two detection areas adjacent to each other in the vertical direction and the position of the other representative point of the other are horizontally shifted by a predetermined amount.