JPH0330586A - Motion detection circuit - Google Patents

Abstract

PURPOSE:To improve the quality of a moving picture by controlling the size of the edge detection signal of a vertical edge component by a horizontal edge component in respect of a picture having the vertical edge component. CONSTITUTION:A vertical edge detection circuit 18 generates the difference signal of a picture elements (a) and (b), and detects the presence or the size of a vertical edge, and a horizontal edge detection circuit 19 generates the difference signals of the picture elements (a) and (d) and the picture elements (a) and (e), and supplies the maximum value of them to a vertical edge quantity control circuit 22 as horizontal edge quantity. Thus, when the horizontal edge component is smaller than a prescribed value, an inputted edge signal is outputted as it is, and when the horizontal edge component exceeds the prescribed value, vertical edge quantity is reduced according to the size of the horizontal edge component. Accordingly, in respect of the picture having the horizontal edge component and the vertical edge component like an oblique line, they can be easily decided as the moving picture.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention determines whether a human-powered video signal is a still image or a moving image, and converts the human-powered video signal from an interlaced scanning format. The present invention relates to a motion detection circuit used in a motion adaptive progressive scan conversion circuit that converts to a progressive scan type.

(Prior art) In NTSC television broadcasting, a 2:1 interlaced scanning method is used.
It enables transmission using a narrow frequency band. but,
Interlaced scanning has drawbacks such as the occurrence of line flicker disturbances, and this disturbance has become more noticeable on the screen, especially as television receivers have become higher in brightness and have larger screens. Therefore, a method has been developed to convert a 2:1 interlaced signal into a progressive scan rK signal by employing a motion adaptive progressive scan conversion circuit using a field memory and a line memory.

The following method is used to convert a 2:1 interlaced video signal into a progressive scanning signal. It determines whether it is a still image or a moving image on a pixel or block basis, and in the case of a still image, generates an interpolation signal for sequential scanning from the previous field,
In the case of a moving image, interpolation signals are generated from pixels on adjacent horizontal scanning lines within the current field. To determine whether a still image or a moving image exists, a difference signal is formed between the signal delayed by one frame period and the current sample signal, and the determination is made based on the magnitude of this signal, and the interpolated signal from the previous field and the interpolated signal from the current field are The mixing ratio is controlled.

In conventional progressive scan conversion, inter-frame difference signals are generated due to noise mixed in the signal transmission path and other parts.
There was a problem in that it misjudged still images/videos. In particular, when noise occurs at vertical edges, it appears as a significant disturbance in the converted and reproduced image, resulting in a significant deterioration in image quality. As a countermeasure to this, the vertical edge component is detected, and if its value is large, the complementary 18
There is a method of reducing the interference signal at the vertical edge portion by increasing the specific weight of one signal.

FIG. 6 is a block diagram showing a conventional motion detection circuit. In FIG. 6, the video signal input through the input terminal 11 is transmitted to the subtraction circuit 14 and the 52511 delay circuit 13.
The subtraction circuit 14 outputs a one-frame difference signal. This difference signal is input to the absolute value circuit 15, becomes an absolute value signal, and is input to the coring circuit 17 via the low-pass filter 16.

On the other hand, the circuit composed of the IH delay circuit 20 and the subtraction circuit 21 is a part that generates a difference signal between lines.

The signal obtained from the subtraction circuit 21 is also input to the absolute value circuit 44, and its absolute value output is given to the characteristic control terminal of the coring circuit 17 as a vertical edge detection signal.

FIG. 7 shows the characteristics of the coring circuit 17, with the vertical axis showing the motion detection signal obtained from the low-pass filter 16, and the horizontal axis showing the motion determination signal. This characteristic is changed to the characteristic shown by the broken line or the characteristic shown by the solid line, depending on the vertical edge detection signal. When the vertical edge detection signal becomes large, it changes in the direction of the solid line, and when the vertical edge detection signal becomes small, it changes in the direction of the broken line. In other words, since a high level of the vertical edge detection signal may be due to the influence of noise, etc., the motion determination signal is maintained at 0 (still image) state until the level of the motion signal becomes relatively large. . This maintains the proportion of field interpolation signals greater than the proportion of line interpolation signals. However, when the level of the vertical edge detection signal is low, the motion determination signal is designed to follow the motion detection signal with high sensitivity.

This makes it possible to reduce interference at the vertical edge, especially when the level of the vertical edge detection signal is high.

FIG. 8 shows a circuit for converting a video signal from a 2:1 interlaced signal to a progressive scanning signal. The video signal at the input terminal 11 is input to a field interpolation circuit 2, a line interpolation circuit 3, and a motion detection circuit 4. The motion detection circuit 4 has a circuit configuration as shown in FIG.

The outputs of the field interpolation circuit 2 and the line interpolation circuit 3 are input to a mixing circuit 5, and the mixing ratio thereof is controlled according to the motion detection signal from the motion detection circuit 4. When the movement is large, the output from the line interpolation circuit 4 has a large weight, and when the movement is small, the output from the field interpolation circuit 2 has a large weight. An interpolated signal from the mixing circuit 5,
The signal from the input terminal 11 is input to the double speed conversion circuit 6 and time-compressed so that the number of scanning lines is doubled.

However, according to the above circuit, if there is a video with vertical edge components for coring control,
Since the proportion of interpolated signals from the previous field increases, a disturbance appears in which the outline of the image appears multi-lined. This is because the output sensitivity of the motion signal is affected as shown in FIG. In particular, in the case of a moving image having diagonal components, since the diagonal lines have vertical edge components, the interpolation signal is mixed with a high proportion of the field interpolation signal.

Furthermore, in order to reduce the influence of mixed noise, the frame difference signal is derived through a low-pass filter and becomes a motion signal, so the amount of frame difference is reduced in the horizontal edge portion. Since the image is determined to be a still image by coring control, there remains the problem that the outline becomes multi-lined and easily visible as described above.

(Problems to be Solved by the Invention) A conventional motion detection circuit detects a vertical edge component and performs coring control on a motion detection signal based on the magnitude of the edge. Furthermore, since the motion detection signal is obtained from the inter-frame difference signal through a low-pass filter, the magnitude of the motion detection signal cannot be obtained accurately (small) at the horizontal edge portion, resulting in an image with vertical and horizontal edge components. The disadvantage is that when the contour moves, the outline becomes multi-lined or jagged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motion detection circuit that can improve the image quality of a moving image by controlling the magnitude of an edge detection signal of a vertical edge component using a horizontal edge component for an image having vertical edge components.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides means for obtaining a difference signal between frames using a human video signal and outputting a motion determination signal according to the absolute value of the difference signal; means for detecting a vertical edge from the input video signal; means for controlling the output characteristic of the motion determination signal based on the detected vertical edge detection signal; further means for detecting a horizontal edge of the input video signal; The vertical edge detection signal is controlled in accordance with the signal, and the magnitude of the horizontal edge detection signal is related to the output characteristic control of the means for outputting the motion determination signal.

(Function) With the above means, when there is no horizontal edge, it is possible to increase the weight of the interfield interpolation signal at the vertical edge depending on the presence or absence and size of the vertical edge, thereby improving image quality. If there is an edge, it is possible to increase the weight of the in-field sleeve opening signal and improve the image quality of the moving image.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a human video signal is supplied to an input terminal 11, and is supplied to a 52511 delay circuit 13 and a subtraction circuit 14. The subtraction circuit 14 has 1
A difference signal between frames appears. This difference signal is inputted to the absolute value circuit 15, becomes an absolute value signal (motion detection signal), and is inputted to the coring circuit 17 via the low-pass filter 16.

Furthermore, the human video signal is input to a vertical edge detection circuit 18 and a horizontal edge detection circuit 19. Vertical edge detection circuit 18 takes the difference between adjacent scan lines, takes the absolute value of this difference signal, and derives a first vertical edge detection signal.

The vertical edge detection signal becomes a second vertical edge detection signal via the vertical edge amount control circuit 22 and is supplied to the characteristic control terminal of the coring circuit 17.

Further, the horizontal edge detection circuit 19 obtains a difference signal between pixels in the horizontal direction or between blocks of a plurality of pixels, takes the absolute value of this difference signal, and outputs this as a horizontal edge detection signal H8. This horizontal edge detection signal H8 is supplied to the control terminal of the vertical edge amount control circuit 22. Thereby, the gain of the first vertical edge detection signal is controlled in the vertical edge amount control ga circuit 22, and the second vertical edge detection signal S is generated. The signal is then supplied to the characteristic control terminal of the coring circuit 17.

The characteristics of the coring circuit 17 are as explained in the seventh factor.

FIG. 2 is a pixel explanatory diagram shown to explain the operation of the circuit of the embodiment. The solid lines are pixels on the scanning line sent in a certain field, and the broken lines are the scanning lines to be interpolated in this field. The X marks represent pixels to be interpolated.

The vertical edge detection circuit 18 generates a difference signal between pixels a and b, and detects the presence or absence or size of a vertical edge. The horizontal edge detection circuit 19 generates difference signals between pixels a and d and between pixels a and e, and uses this maximum value as the water 51i-
It is given to the vertical edge amount control circuit 22 as the edge amount.

FIG. 3 shows the characteristics of this vertical edge amount control circuit 22. The vertical edge amount control characteristic for the horizontal edge detection signal (component) HO is that if the horizontal edge component is smaller than a predetermined value, the input vertical edge signal is output as is, and if the horizontal edge component exceeds the predetermined value, the input vertical edge signal is output as is. represents subtracting the vertical edge amount according to the size of the horizontal edge component.

As a result, an image having horizontal edge components and vertical edge components such as diagonal lines can be easily determined as a moving image, and it is possible to reduce interference when the image is actually a moving image and moves.

FIG. 4 shows a specific example of the structure of the vertical edge detection circuit and horizontal edge detection circuit.

The video signal at the input terminal II is supplied to the IH delay circuit 201 and also to the subtraction circuits 14, 21, and 34.

Furthermore, it is supplied to the delay circuit 30 and the 525 I+ delay circuit 13. The output of the subtraction circuit 14 is supplied to an absolute value circuit 15, its absolute value is taken, and this output is input to a coring circuit 17 via a low-pass filter te.

The output of the delay circuit 30 is input to a subtraction circuit 34.

As a result, the subtraction circuit 34 obtains the store name for one minute between pixels, and the absolute value thereof is obtained in the absolute value circuit 40. Further, the output of the delay circuit 30 is input to a delay circuit 31 and a subtraction circuit 35, and the output of the delay circuit 31 is also supplied to the subtraction circuit 35. The absolute value of the output of the subtraction circuit 35 is taken by an absolute value circuit 41. IH
The part to which the output of the delay circuit 20 is supplied, that is, the delay circuit +
! 632.33, subtraction circuit 3B, 37, absolute value circuit 42
．． The configuration of circuit 43 is also the same as that of delay circuit 30.31, subtraction circuit 34.35, and absolute value circuit 40.41. The outputs of the absolute value circuits 40, 41, 42, 43 are input to the maximum value circuit 50. The maximum value circuit 50 selects the maximum value from the widths of the detection signals given from the absolute value circuits 40, 41, 42, 43 and supplies it to the control terminal of the vertical edge amount control circuit 22.

The input section of the vertical edge amount control circuit 22 includes a subtraction circuit 2.
The output of 1 is input to the absolute value circuit 44 and the absolute value is taken, and a signal of this value is input via the delay circuit 39.

In the above embodiment as well, the maximum value in the horizontal edge signal is detected, and the motion determination signal S based on the vertical edge is detected in the horizontal edge portion. output characteristics are varied. That is, when there is a horizontal edge, the level of the vertical edge detection signal is lowered to increase the relative weight of the interpolation signal within the field. As a result, even when an image with vertical edges moves, a motion detection signal can be obtained appropriately, and the outline does not appear multilined as in the conventional case.

FIG. 5 is a diagram shown to explain the operation of the embodiment shown in FIG. 4. That is, in this embodiment, the IH delay circuit 20
Since the horizontal edge signal is detected using the input and output signals of the pixels a, b,
This means that d, e, f, and g are used. The dotted lines are interpolation scanning lines, and the solid lines are upper and lower scanning lines.

Ib-gl is obtained from the absolute value circuit 40, If-bl is obtained from the absolute value circuit 41, 1a-el is obtained from the absolute value circuit 42, and 1d-al is obtained from the absolute value circuit 43, respectively. The maximum value circuit 50 selects and derives the maximum of the above absolute values. The characteristics of the vertical edge amount control circuit 22 are those shown in FIG. 3, and the vertical edge components la-b-l are controlled by outputting the maximum value.

Although the above embodiment has been described as being constituted by each functional circuit block, the present invention can also be realized by software using a microcomputer.

[Effects of the Invention] As described above, the present invention can improve the image quality of a moving image by controlling the magnitude of the edge detection signal of the vertical edge component using the horizontal edge component for an image having the vertical edge component.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram shown to explain the operation of the circuit in FIG. 1, and FIG. 3 is a characteristic of the vertical edge amount control circuit in FIG. 1. Figure 4 showing
The figure is a circuit diagram showing another embodiment of the present invention, and FIG.
6 is a circuit diagram showing a conventional motion detection circuit, FIG. 7 is a diagram showing characteristics of a coring circuit,
FIG. 8 is a diagram showing a scanning line conversion circuit. 13...525H delay circuit, 14...Subtraction circuit, 1
5...Absolute value circuit, te...Low pass filter, 17.
... Coring circuit, 18... Vertical edge detection circuit,
19...Horizontal edge detection circuit, 22...Vertical edge amount control circuit.

Claims (2)

[Claims] (1) means for obtaining a difference signal between frames using an input video signal and outputting a motion determination signal according to the absolute value of the difference signal; means for detecting a vertical edge from the input video signal; means for controlling the output characteristics of the motion determination signal so as to reduce the sensitivity of the motion determination signal when the vertical edge is large and to increase the sensitivity when the vertical edge is small, based on the vertical edge detection signal detected by the input video signal; and controlling the vertical edge detection signal so that the vertical edge detection signal becomes small when the horizontal edge detection signal is large, according to the horizontal edge detection signal detected by the means, 1. A motion detection circuit comprising: means for relating the magnitude of the horizontal edge detection signal to output characteristic control of the means for outputting the motion determination signal. (2) In a motion detection circuit that obtains motion information using an interframe difference signal generation means that has at least one frame delay circuit and a subtraction circuit and obtains at least one interframe difference signal of a video signal, interpolation of progressive scan conversion is performed. a means for detecting a first vertical high frequency component and a means for detecting a horizontal high frequency component in the vicinity of the pixel; and a means for detecting a horizontal high frequency component in the vicinity of the pixel; A motion detection circuit comprising: a means for controlling a detection signal of and obtaining a second vertical high-frequency component; and a means for coring-controlling an inter-frame difference signal using the second vertical high-frequency component. .