JPS6225588A - Detector circuit for moving vector - Google Patents

Abstract

PURPOSE:To well correct the movement of the image such as an object moves into the screen by correcting a moving vector of an input picture that includes an area overlapping with an output picture by using a moving vector of the input picture that does not overlap with the output picture. CONSTITUTION:Gate circuits 2A, 2B, and 2C respectively connected to an input terminal 1 let the picture elements included in a left-side area of input picture 1A, a right-side area of input picture 1B, and a central area 1C pass, and supply them to moving-vector detector circuits 5A, 5B, and 5C. The first moving vector Vc detected in the first area of input picture that includes the area 1C overlapping with the output picture, is a major moving vector. The movement of the object into the scope or out of the screen is detected by means of the other moving vectors Va and Vb in order to correct the raising and the falling of the moving vector 1C.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to, for example, high-definition television system (so-called HD
The present invention relates to a motion vector detection device that is applied to a field number conversion device of a format conversion device that converts a PAL format into a PAL format.

[Summary of the invention]

The present invention is applicable to a motion vector detection device used when an input image is larger than an output image in terms of horizontal or vertical length, such as a system conversion device from an HD system to a PAL system. When detecting a motion vector of an image, a second motion vector is detected in a second region of the input image that does not overlap with the output image, and a first motion vector is detected in a first region of the human-powered image that overlaps with the output image. The motion vector detection device is capable of smooth motion correction by detecting a vector and forming a motion vector for motion correction using not only the main first motion vector but also the second motion vector. .

[Conventional technology]

As a motion vector detection Wit applied to a television format conversion device, there is a known motion vector detection Wit that utilizes motion correction that can prevent unnatural motion in a converted image like simple thinning processing. (1125 lines/6
A field number conversion device using motion compensation is also used in a format conversion device that converts an HD format (0 fields) to a PAL format (625 lines, 150 fields).

The HD system and the PAL system have different screen aspect ratios. The HD system is (5:3), and the PA
The L method is (4:3). In the conventional format conversion device, as described in Japanese Patent Application Laid-Open No. 59-122286, the areas at both ends of the HD format input image are cut off. In addition, even when using motion compensation, as shown in Figure 3, the areas for detecting motion in the input image are areas with a width of 10% on each side of the screen with an aspect ratio of (5:3). Only the central area IC, which overlaps the output image, was used, excluding areas IA and IB. This means that if motion is detected in all areas of the input image, even if the subject moves in areas IA and 1B on both sides outside the output image, motion compensation will be performed, and area IC in the center and areas on both sides will be corrected. This is because if there is a difference between the movements of LA and IB, accurate movement detection cannot be performed.

[Problem that the invention seeks to solve]

As shown in Figure 3, in the case of an image in which a car as a subject crosses the screen from the right side to the left side at a constant speed,
Conventional motion vector detection devices do not detect motion vectors in region IB, and therefore have the disadvantage that motion vectors cannot be detected unless the vehicle enters the central region IC to some extent and the area of the moving portion becomes large. In addition, in order to suppress sudden changes and eliminate screen jumps and movement discontinuities, the detected motion vector is usually
Filtering is performed using a low-pass filter.

Therefore, it takes time from when a motion vector is detected in the area IC until motion correction is performed. For these reasons, the output image has the disadvantage that it looks unnatural, like a car starting after stepping on the brake.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a motion vector detection device that can effectively perform motion correction of an image in which a subject moves into the screen.

[Means for solving problems]

In this invention, when forming an output image having a horizontal or vertical length smaller than at least one of the horizontal length of the input image or the vertical length of the input image, In a motion vector detection device that detects a vector, a first motion vector Vc is detected in a first region of the input image including a region IC that overlaps with the output image, and a first motion vector Vc is detected in a second region IA of the input image that does not overlap with the output image. and second in IB
A motion vector detection device is characterized in that it detects motion vectors Va and Vb of .

[Effect]

The first motion vector VC detected in the first region of the human image including the region IC overlapping with the output image is the main motion vector. In addition, since the second motion vectors Va and Vb are detected in the second areas IA and IB of the input image that do not overlap with the output image, the object is detected within the screen from the second motion vectors Va and Vb. It is possible to detect the movement of objects entering or exiting the screen.

Therefore, when it is detected that a subject enters the screen, the motion vector starts rising quickly, and on the other hand,
If it is detected that the subject is leaving the screen,
By slowing down the fall of the motion vector, it is possible to form a motion vector that can perform good motion correction.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. This description is given in the following order.

a. Motion vector detection processing circuit. C. Overall configuration of system conversion device. C. Field number conversion circuit d. Modification a. Motion vector detection processing circuit FIG. 1 shows an embodiment of the present invention. In FIG. 1, an input terminal designated by 1 is supplied with a digitized video signal. For example, when converting from an HD system to a PAL system, motion compensation is used to convert the number of fields. The input terminal 1 is supplied with an HD digital video signal whose number of lines has been converted to 625.

Gate circuits 2A, 2B, and 2C are connected to the input terminal 1, respectively. The gate circuit 2A passes the pixels included in the left area IA on the screen of the input image, and the gate circuit 2B
The gate circuit 2C allows the pixels included in the right region IB to pass through, and the gate circuit 2C allows the pixels included in the center region IC to pass through. As shown in FIG. 3, the central area IC is an area that overlaps with the output image, and areas IA and IB on both sides.
is an area that does not overlap with the output image.

Outputs of gate circuits 2A, 2B, and 2C are supplied to motion vector detection circuits 5A, 5B, and 5C, respectively.

The motion vector detection circuits 5A, 5B, and 5G have a representative point configuration using block matching. FIG. 2 shows an example of a motion vector detection circuit that can be used as the motion vector detection circuits 5A, 5B, and 5C. The representative point method using block matching subdivides an image into a large number of detection areas (also called blocks), uses the center position of this detection area as the representative point, and uses the representative point of the previous frame and the detection area of the current frame as the representative point. A frame difference with respect to a pixel is calculated, the absolute value of this frame difference is totaled over one field, and the position of the minimum value among the total frame differences is taken as a motion vector.

A digital video signal from an input terminal indicated by 11 is supplied to a subtraction circuit 12 and a representative point selection circuit 13. The representative point data selected by the representative point selection circuit 13 is stored in the representative point memory 14. The representative point data of the previous frame read from the representative point memory 14 is supplied to the subtraction circuit 12, and frame difference data ΔF is obtained from the subtraction circuit 12.

For example, a motion vector detection area of 9 pixels in the X direction (horizontal direction) and 7 lines in the y direction (vertical direction) is set, and the entire screen of one field is divided into a large number of detection areas. The detection area may be set to partially overlap with other adjacent detection areas. With the center of this detection area as the origin, (x,
y) Coordinates are determined. This origin is taken as the representative point. The motion vector is determined for each pixel within the detection area.

The subtraction circuit 12 calculates the difference (frame difference data) Δ between the representative point of the previous frame read out from the representative point memory 14 and each of all the pixels of the current frame included in the detection area of this representative point.
Form F.

The frame difference data ΔF from the subtraction circuit 12 is sent to the conversion circuit 1.
5 and is converted into absolute value frame difference data 1ΔF1. This data 1ΔF1 is supplied to the aggregation circuit 16. The aggregation circuit 16 is a digital integration circuit that has a memory corresponding to the detection area and accumulates all the absolute value frame difference data 1ΔF1 of the area targeted for motion detection for each pixel position within the detection area. A table of frame difference total data Σ1ΔF1 is stored in the memory of this total circuit 16. A minimum value detection circuit 17 connected to the aggregation circuit 16 detects the minimum value in the table of frame difference aggregation data described above as a motion vector. This detected motion vector is obtained at the output terminal 18.

The motion vector detection circuit 5A detects the motion vector Va in the area IA, and the motion vector detection circuit 5B detects the motion vector Va in the area IB.
The motion vector detection circuit 5 detects the motion vector vb of
C detects the motion vector Vc of the region IC. These detected motion vectors Va, Vb, and Vc are supplied to the determination circuit 6. Further, the detected motion vector Vc is supplied to the digital low-pass filter 7.

This digital low-pass filter 7 is provided to suppress sudden changes in the IJJ vector and reduce screen jumps and discontinuities in motion. This digital low-pass filter 7 is configured so that its characteristics can be varied by a control signal from the determination circuit 6. That is, the control signal causes the motion vector to fall later than usual, or the control signal causes the motion vector to rise earlier than usual.

The determination circuit 6 forms a control signal based on the motion vectors Va, Vb, and Vc extracted from the areas LA, IB, and IC, respectively. The control signal is generated when the subject moves out of the screen and when the subject moves into the screen. The combination of motion vectors Va, Vb, and Vc when this control signal is generated is as follows.

Case 1 in the table above is an image where the subject exits from within the screen towards the left, and case ii is an image where the subject exits from within the screen towards the right. When the subject leaves the screen, the falling characteristic of the low-pass filter 7 is made slower than usual, and the area IC
The magnitude of the motion vector at is held as much as possible. This control processing suppresses a decrease in the magnitude of the motion vector when the subject leaves the screen, and prevents the speed of the subject from slowing down when the subject leaves the screen.

Case iii in the table above is an image in which the subject enters from the right side of the screen and moves to the left, and case i
v is an image in which the subject enters the screen from the left side and moves to the right. When a subject enters the screen, the rising characteristic of the low-pass filter 7 is made faster than usual, and the motion vector in the area IC rises immediately from the edge.

Note that / in the above table means a motion vector that is not considered by the determination circuit 6. In addition, in cases other than the raw salt mentioned above,
The characteristics of the low-pass filter remain as normal.

The motion vector taken out to the output terminal 8 is used for motion correction when the format conversion device converts the number of fields. Motion correction is a process of forming an image shifted by a predetermined amount based on a motion vector.

Also, unlike the motion vector detection circuit shown in FIG. 1, the motion vector Va is detected over several frames.

A motion vector for motion correction may be formed based on the results of observing Vb and Vc.

b. Overall configuration of format conversion device The present invention converts a high-definition television format (1125 lines/60 fields) to the so-called HD format (625 lines/1 field).
It can be used to convert the number of fields when converting to the PAL system (50 fields). Figure 4 shows this (
1 shows the overall configuration of an HD-PAL (HD-PAL) system conversion device.

In FIG. 4, a luminance signal in a high-definition television signal is supplied to an input terminal indicated by 21, and this luminance signal is supplied to an A/D converter 23 via a low-pass filter 22. A digital luminance signal from the A/D converter 23 is supplied to a preprocessing circuit 24 . This preprocessing circuit 24
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.

Further, from one field of a high-definition television signal, a first field video and a second field video, both of which have 625 lines, are simultaneously formed. The first field image and the second field image are offset by 0.5 line. Therefore, preprocessing circuit 2
4, a digital video signal consisting only of the first field (625 lines/60 frames), and a digital video signal consisting of only the first field (625 lines/60 frames);
A digital video signal consisting only of the second field (line/60 frames) is obtained. Motion vector detection is performed using the video signal of the first field, and field number conversion processing is performed separately for each of the first field and the second field. Preprocessing circuit 2
In step 4, by performing the above-mentioned non-interlacing, detection accuracy can be improved by detecting a motion vector every 1/60 seconds, and it becomes easy to form an interpolation signal.

Reference numeral 25 indicates a motion vector detection processing 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 processing circuit 25. Further, the field number conversion circuit 31 regarding the first field and the second
A field number conversion circuit 32 for fields is provided, and detected motion vectors are supplied to these field number conversion circuits 31 and 32.

The motion vector detection processing circuit 25 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 calculates the field difference total data. This is a configuration that detects the minimum value of field difference aggregate data. In this case, as described above, areas IA, 1B of the input image
, the motion vectors Va, V detected for each of the ICs
An image shift command for motion compensation is formed from b and Vc.

Further, the field number conversion circuit 31 outputs the first field digital video signal (625 lines, 150 frames), and the field number conversion circuit 32 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 31 and 32 are sent to the switch circuit 41.
supplied to The switch circuit 41 includes one
A control signal that is inverted every 750 seconds is supplied, and the output of the switch circuit 41 is (625 lines 150 fields).
A digital luminance signal is extracted.

This digital luminance signal is supplied to the D/A converter 42. The output signal of the D/A converter 42 is supplied to a PAL color encoder 44 via a low pass filter 43. 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 44. Therefore, a PAL composite color television signal is obtained at the output terminal 45 of the PAL color encoder 44. A PAL color television receiver is connected to the output terminal 45.

C. Field number conversion circuit The field number conversion circuit 31 includes a field memory 33, a motion correction circuit 34, a linear approximation circuit 35, and a switch circuit 3.
6, an erroneous processing detection circuit 37, and a memory 38. The field number conversion circuit 32 has the same configuration as the field number conversion circuit 31.

Both the previous field digital video signal from the field memory 33 and the manually inputted current field digital video signal are supplied to a motion correction circuit 34, a linear approximation circuit 35, and an error processing detection circuit 37. Motion correction circuit 34
One of the output signal of the linear approximation circuit 35 and the output signal of the linear approximation circuit 35 is selected by the switch circuit 36. The switch circuit 36 is controlled by the detection output of the erroneous processing detection circuit 37, and selects the corrected output that has been processed more correctly.

The erroneous processing detection circuit 37 is supplied with both a signal obtained by shifting the image of the previous field formed in the motion correction circuit 34 and a signal obtained by shifting the image of the current field.

Furthermore, a memory 38 to which the output of the switch circuit 36 is supplied
is for time axis extension.

An example of motion correction performed by the motion correction circuit 34 is shown in the fifth example.
This will be explained with reference to the figures. In FIG. 5, Fl, F2.
F3. F4. F5. F6 indicates six consecutive first field images. In this image, from left to right (1/6
0) Contains a moving object that moves at a constant velocity and moves a distance of A every second. This A is the motion vector detection circuit 25
It is nothing but the motion vector from . In the case of this uniform motion, the total amount of movement from image F1 to image F6 is
It becomes 5A.

When converting these six images F1 to F6 into five images [1 to f5, it is necessary to increase the moving distance by (115) A. Therefore, the image Fl is obtained by shifting the image F1 by (115)A. Similarly, image F2. F3
．． F4. F5 respectively (215) A, (315)
A, (415) A, By shifting A, the image f2. f3. f4. F5 is formed.

Since the image F5 shifted A and the image F6 not shifted at all have the same pattern, one of them is removed. Image shifting can be achieved by memory address control.

In this motion correction, in the case of banging or tilting, complete conversion of the number of fields is possible if the motion vector can be detected accurately. However, in an actual image, there are parts of the screen that move in various ways, parts of the screen that are stationary, and parts that cause problems due to shifting. In such a case, the output of the linear approximation circuit 35 is sent to the switch circuit 3 instead of the output of the motion correction circuit 34.
6 is selected.

The linear approximation circuit 35 is configured as an interpolation circuit that multiplies each of two consecutive fields of video by a predetermined weighting coefficient and adds the multiplication outputs. An example of correction by the linear approximation circuit 35 will be described with reference to FIG.

Images F1 to F6 are six consecutive images taken every (1/60) second. This image includes both a moving object that is moving at a constant velocity and a stationary object. Image Fl (415)
The image r1 is formed by adding the image F2 multiplied by the weighting factor of (115) and the image F2 multiplied by the weighting factor of (115). In FIG. 6, the broken line indicates the pattern of the image in the subsequent field. Also, in image F2 (315
) is multiplied by the weighting coefficient of (215), and image F3 is multiplied by the weighting coefficient of (215).
is formed.

Similarly, image "3" is formed by (215F 3 +315 F 4 ), and (115F 4 +415 F
5'), the image r4 is formed, and the image F6 is the image r
It is considered to be 5.

This linear approximation circuit 35 has the problem of doubling or blurring for moving parts, but for stationary parts, correction by linear approximation is better than motion correction. An erroneous processing detection circuit 37 detects whether or not the motion correction circuit 34 is erroneously processing.

FIG. 7 shows the configuration of an example of the erroneous processing detection circuit 37. In FIG. 7, the digital video signal of the previous field F1 is supplied to the input terminal indicated by 51, and the digital video signal of the current field F2 is supplied to the input terminal indicated by 52. Both digital video signals are subtracted by a subtraction circuit 53 pixel by pixel, and the difference ΔFL between the signals of both fields is determined. Further, the signal of the field fil, in which the image of the previous field F1 is shifted by (215) A, is supplied to the input terminal indicated by 54, and the image of the current field F2 is shifted by (-315) A to the input terminal indicated by 55.
A signal of shifted field f12 is supplied. Both fields fil and F12 are subtracted by a subtraction circuit 56 pixel by pixel, and the difference Δ between the signals of both fields is
f is found.

Difference signals ΔFL and Δf are compared by comparison circuit 57. As shown in FIG. 8, the image of the previous field F1 is
15) The image of field [11] shifted by A and the image of field f12 shifted by (-315) A from the image of current field F2 are the same in terms of moving parts, and the difference between the two images Δf is shown in FIG. As shown in , the moving parts have been removed. On the other hand, the unshifted previous fields F1 and F2 are the same with respect to the stationary portion.

Therefore, by the comparison operation of the comparison circuit 57, (AFL>
For pixels where Δf) is detected, it can be determined that the motion correction process is correct, and conversely, for pixels where (AFL<Δf) is detected, it can be determined that the motion correction process is incorrect.

The comparison circuit 57 generates a comparison output which becomes .degree.H' when (AFL>.DELTA.f) and becomes .degree.L' when (AFL<.DELTA.f). This comparison output is supplied to majority logic circuit 58. The majority logic circuit 58 makes a determination for each motion vector detection area. Regarding the comparative output of a plurality of pixels included in one detection area, when the number of °H" is greater than the number of °L", an output signal of °H" is generated at the output terminal 59,
Conversely, when the number of L degrees is greater than the number of degrees H'', the output terminal 59
An output signal of "L" is generated. This output signal is used as a control signal of the switch circuit 36. The switch circuit 36 is
When the output of the erroneous processing detection circuit 37 is H', the corrected signal from the motion correction circuit 34 is selected, while when the output of the erroneous processing detection circuit 37 is L°, the corrected signal from the linear approximation circuit 35 is selected. Select the selected signal.

The motion correction circuit 34 may have a structure that uses both the current field image and the previous field image, as shown in FIG. 9, unlike the structure that performs the motion correction operation shown in FIG. 5 described above.

In FIG. 9, similarly to the example shown in FIG. 5, six consecutive images F1 to F6 of the first field include a moving object that moves at a constant velocity. This is an example of converting an image into five images r1 to f5. Image F1 (11
5) A shifted image and image F2 (-415)
The A-shifted values are added, and this addition output is 172
As a result, image f1 is formed. Image F2 (
215) A shifted image and image F3 (-315)
An image f2 is formed from the A-shifted image. Image F
3 by (315) A shift and image F4 by (-2
15) Image f3 is formed from the A-shifted image.

Image f4 is formed from image F4 shifted by (415) A and image F5 shifted by (-115) A. Image f5 is formed from image F5 shifted by A and image F6.

Although not shown, since the image formed from the image F6 and the next image F7 shifted by -A has the same pattern as the image f5, one of the overlapping images is removed. Thereafter, the correction operation shown in FIG. 9 is repeated again. The process of shifting the previous field by (a15) A and shifting the current field by (-(5-a)15) A can be used in combination with the shift process required for the above-mentioned erroneous processing detection.

Furthermore, an image in which the previous field is shifted by (a15) A and an image in which the current field is shifted by (-(5-a)/5) A are basically the same image. However, by adding the two, it is possible to equalize the S/N for random noise in the case of linear approximation and the S/N for random noise in the case of motion compensation. Sometimes the effect of blurring the image can be obtained.

d. Modification In the present invention, the regions IA, IB, and IC may be set in a relationship that partially overlaps each other. Further, when the input image is larger than the output image in the vertical direction, the present invention can be applied to the detection process of the vertical motion vector.

〔Effect of the invention〕

According to this invention, it is possible to detect the presence of a subject entering the screen or a subject going out of the screen from a motion vector detected in an area outside the range of the output image. Smooth motion correction can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of an example of a motion detection circuit that can be used in the present invention,
FIG. 3 is a route map used to explain an embodiment of the present invention, FIG. 4 is a block diagram of an example of a system conversion device to which this invention can be applied, and FIG. 5 is an explanation of an example of motion correction in the system conversion device. 6 is a route map used to explain an example of linear approximation in a system conversion device, FIG. 7 is a block diagram of an example of an erroneous processing detection circuit in a system conversion device, and FIG. 8 is an erroneous processing detection circuit. FIG. 9 is a route map used to explain another example of motion correction. Explanation of main symbols in the drawings 1: Digital video signal input terminals, 2A, 2B, 2
C: Gate circuit, 5A, 5B. 5C: Motion vector detection circuit, 6: Judgment circuit, 7:
Low-pass filter, 25: Motion vector detection processing circuit, 31.32: Field number conversion circuit, 34: Motion correction circuit. Agent Patent Attorney Masato Sugiura Figure 1

Claims (1)

[Claims] When forming an output image having a horizontal or vertical length smaller than at least one of the horizontal length of the input image or the vertical length of the input image, In a motion vector detection device that detects a motion vector of an input image, a first motion vector is detected in a first region of the input image that includes a region that overlaps with the output image, and the input image that does not overlap with the output image detects a first motion vector. A second motion vector is detected in a second region of the motion vector, and a motion vector for motion correction is formed from the first motion vector and the second motion vector. Device.