JPS6225590A - Detection method for moving vector - Google Patents

Abstract

PURPOSE:To accurately detect the moving of fine vertical streak by horizontally shifting the representative point of one of the two vertically neighboring detection areas and that of another area for a prescribed amount instead of vertically aligning the positions of the representative points in an movement-detection method of representative-point system. CONSTITUTION:The representative point 3 is determined for each one two-dimensional detection area formed by plural picture elements in one same field, and the difference DELTAF between the representative point in one of the two corresponding fields and respective picture elements in the direction area of the other field is calculated 2. The absolute values of the said difference DELTAF are totalled to make an absolute-value totalling data SIGMA¦DELTAF¦, from which a minimum value is detected 7. The minimum value is detected as a moving vector. In this moving-vector detection method, the representative point of one of the two vertically neighboring detection areas and that of another area are shifted in the horizontal direction for a prescribed amount to amplify the detection effect of the moving vector in case of a vertical streak like picture.

Description

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

[Summary of the invention]

This invention divides a television signal into a large number of detection areas, determines a representative point for each detection area, calculates the absolute value of the difference between the representative point of the corresponding 2' field and each pixel within the detection area, and calculates this difference. In a representative point method motion vector detection method using so-called block matching, in which the absolute values of two vertically adjacent detection areas are aggregated and the minimum value of the absolute value aggregated data is detected as a motion vector, By adjusting the position of one representative point and the position of the other representative point by a predetermined amount in the horizontal direction, it is possible to accurately detect the motion vector of a pattern such as vertical stripes.

[Conventional technology]

One method for detecting motion in television images is to divide the television image into a large number of block-shaped detection areas and perform a matching judgment between corresponding detection areas between the previous frame and the current frame. A block matching method for detecting is known. Among these block matching methods, there is a representative point method that can simplify hardware and shorten processing time.

In the conventional representative point motion vector detection method using block matching, as shown in FIG. 4, detection areas are defined like the eyes of a base, and the center position of each detection area is used as a representative point. In other words, the size of the detection area is (X pixels x Y lines)
Then, the representative points were set at the center positions represented by (X/2) and (Y/2), and the lines connecting these representative points were in the form of a grid, as shown by broken lines. In the example shown in FIG. 4, the interval between representative points in the horizontal direction is X.

[Problem that the invention seeks to solve]

In the conventional motion vector detection method, since the representative points of each detection area are aligned in the vertical direction, it may not be possible to detect the movement of naturally existing patterns such as fine vertical stripes that have a high spatial frequency. In other words, a movement in which the position of the vertical stripe in the previous frame and the position in the current frame are apparently different 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 that can accurately detect motion vectors even in the case of images with patterns such as fine vertical stripes.

[Means for solving problems]

This invention defines a two-dimensional detection area formed by a plurality of pixels in the same field and a representative point for each detection area, and detects the representative point of one field of two corresponding fields and the other field. In a motion vector detection method in which the minimum value is detected from the absolute value aggregated data in which the difference between each pixel within the area is calculated and the absolute value of the difference is aggregated, and this minimum value is detected as a motion vector, This is a motion vector detection method characterized in that the position of one representative point of two adjacent detection areas is shifted by a predetermined amount in the horizontal direction from the position of the other representative point.

[Effect]

Since the representative points of each detection area are not aligned vertically,
The motion vector detection effect for images with vertical stripes can be increased.

〔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 that can be used to implement the present invention. A digital video signal from an input terminal 1 is supplied to a subtraction circuit 2 and a representative point selection circuit 3,
The selected representative point is stored in the representative point memory 4. Decrease/
The arithmetic 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 by the conversion circuit 5 into absolute value frame difference data 1ΔFl. This data 1ΔF1 is supplied to the aggregation circuit 6, and all the data 1ΔF of the field
1 is accumulated for each pixel in the detection area to obtain frame difference total data Σ1ΔF1. The minimum value detection circuit 7 is
The minimum value is detected in the frame difference total data Σ1ΔF1, and this minimum value is output 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 within the detection area is determined, and if the position of this minimum point is a small vector, the frame difference data ΔF is There is a configuration in which the frame difference data ΔF is not counted, or a configuration in which the frame difference between pixels is determined and, if this frame difference is small, the frame difference data ΔF is not counted. These configurations can prevent the motion vector from becoming a zero vector due to a background with sharp changes. The present invention can also be applied to motion vector detection circuits with these improved configurations.

In one embodiment of the present invention, as shown in FIG. A point selection circuit 31 selects the position of the representative point. X is the horizontal interval between representative points. A detection area for X pixels and Y lines is set around each representative point. By determining the representative points in this manner, each detection area is arranged in a checkerboard pattern.

In the example shown in FIG. 2, the relationship is (X=X).

However, in order to increase the detection capability, the detection areas may overlap each other. In addition, one field is divided into four, and a motion vector is detected for each divided area.
The motion vector of one field may be obtained by determining the motion vectors of the following motion vectors.

As described above, the present invention does not align the positions of the representative points in the vertical direction, so it is possible to improve the ability to detect movement of patterns with high spatial frequencies, such as vertical stripes.

This invention converts the high-definition television system (1125 lines/60 fields) to the so-called HD system (625 lines/60 fields).
This method can be applied to field number conversion when converting to a PAL format (50 fields). Figure 3 shows this (
2 shows the overall configuration of an HD→PAL) system conversion device.

In FIG. 3, a luminance signal in a high-definition television signal is supplied to an input terminal indicated by 11, and this luminance signal is supplied to an A/D converter 13 via a low-pass filter 12. A digital luminance signal from the A/D converter 13 is supplied to a preprocessing circuit 14 . This preprocessing circuit 14
performs line number conversion and non-interlacing processing.

The number of lines is converted from 1125 to 625 using, for example, digital frequency conversion technology.

Furthermore, a first field image and a second field image, both of which have 625 lines, are simultaneously formed from one field of a high-definition television signal. This first field image and second field image are 0.5
This is due to the line offset. Therefore, from the preprocessing circuit 14, a digital video signal consisting of only the first field of (625 lines/60 frames) and a digital video signal consisting of only the first field of (625 lines/60 frames) are output.
A digital video signal consisting only of the second field (5 lines/60 frames) is obtained. Detection of the motion vector is performed using the first field video signal,
The field number conversion process is performed separately for each of the first field and the second field. By performing the above-mentioned non-interlacing in the preprocessing circuit 14, detection accuracy can be improved by detecting a motion vector every 1760 seconds, making it easier to form an interpolation signal.

Reference numeral 15 indicates a motion vector detection circuit to which the present invention can be applied, and the digital video signal of the first field is supplied to this motion vector detection circuit 15. Further, 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 supplied to these field number conversion circuits 21 and 22.

The motion vector detection circuit 15 calculates the difference (field difference data) between the representative point of the previous field and the pixel of the current field for each detection area, totals the absolute value of this field difference data, and generates field difference total data. However, it is configured to detect the minimum value of the field difference aggregate data. As described above, in this motion vector detection circuit 15, the positions of one representative point and the other representative point of vertically adjacent detection areas are shifted by a predetermined amount (x/2).

Further, the field number conversion circuit 21 outputs the first field digital video signal (625 lines, 150 frames), and the field number conversion circuit 22 outputs the digital video signal of the first field (625 lines, 150 frames).
A second field digital video signal (625 lines, 150 frames) is output. The output signals of these field number conversion circuits 21 and 22 are sent to the switch circuit 31.
is supplied to The switch circuit 31 includes one
A control signal that is inverted every 750 seconds is supplied, and the output of the switch circuit 31 is (625 lines 150 fields).
A digital luminance signal is extracted.

This digital luminance signal is supplied to the D/A converter 32. The output signal of the D/A converter 32 is supplied to a PAL color encoder 34 via a low-pass filter 33. The red color difference signal R-Y and the blue color difference signal B-Y, which have been subjected to line number conversion and field number conversion in the same way as the luminance signal Y, are supplied to the PAL color encoder 34. Therefore, a PAL composite color television signal is obtained at the output terminal 35 of the PAL color encoder 34. A PAL color television receiver is connected to the output terminal 35.

The field number conversion circuit 21 is a field memo IJ23.
, a motion correction circuit 24 , a linear approximation circuit 25 , a switch circuit 26 , an erroneous 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 from the field memory 23 and the digital video signal of the inputted current field are supplied to a motion correction circuit 24 , a linear approximation circuit 25 , and an erroneous processing detection circuit 27 . Motion correction circuit 24
One of the output signal of the linear approximation circuit 25 and the output signal of the linear approximation circuit 25 is selected by the switch circuit 26. The switch circuit 26 is controlled by the detection output of the erroneous processing detection circuit 27, and selects the corrected output that has been processed more correctly.

The erroneous processing detection circuit 27 is supplied with both a signal obtained by shifting the image of the previous field formed in the motion correction circuit 24 and a signal obtained by shifting the image of the current field.

Furthermore, a memory 28 to which the output of the switch circuit 26 is supplied
is for time axis expansion.

The motion correction circuit 24 converts six consecutive first field images into five images, and performs image shift processing using the motion vector detected by the motion vector detection circuit 15. By taking motion into account, unlike simple thinning processing, the motion of the converted image does not become unnatural.

The linear approximation circuit 25 is an interpolation circuit that multiplies each of two consecutive fields of images by a predetermined weighting coefficient and adds the multiplication outputs. This linear approximation circuit 25 has the problem of double images or blurring for moving parts, but for stationary parts, linear approximation is better than motion correction.

The erroneous processing detection circuit 27 detects the field difference ΔFL between the previous field image and the current field image, and the difference Δf between the image obtained by shifting the previous field image by a predetermined amount and the current field image shifted by a predetermined amount in the opposite direction. detects and
The configuration is such that the magnitudes of the difference signals ΔFL and Δf are compared, and a majority decision is made on the comparison output for each detection area. In other words,(
For pixels in the relationship ΔFL>Δf, the motion correction process is determined to be correct; for pixels in the relationship (ΔFL<Δf), the motion correction process is determined to be incorrect, and It is determined in which relationship there are a large number of pixels with respect to all the pixels. The switch circuit 26 is controlled based on the result of this determination.

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

The present invention can be applied not only to a format conversion device for television signals but also to a motion correction device for a high-efficiency encoding device, a band compression transmission device for high-definition television signals, and the like.

〔Effect of the invention〕

According to the present invention, in a motion detection method using a representative point 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 regions is detected in the other detection region. Since the representative point of the area is shifted by a predetermined amount in the horizontal direction, the movement of fine vertical stripes can be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of a motion vector detection circuit that can be used to implement this invention, FIG. 2 is a route diagram used to explain an embodiment of this invention, and FIG. 3 is a system conversion to which this invention can be applied. The block diagram of the device, FIG. 4, is a route map used to explain the conventional motion vector detection method. Explanation of main symbols in the drawings 1: Input terminal, 22 subtraction circuit, 3: Representative point selection circuit, 6: Aggregation circuit, 7: Minimum value detection circuit. Agent Patent Attorney Masato Sugiura Figure 4

Claims (1)

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