JPH03291080A - Movement adaptive type scanning line interpolation device - Google Patents

Abstract

PURPOSE:To apply moving adaptive scanning line interpolation with less line flicker or the like by providing a circuit detecting the movement of a picture, a circuit detecting a change in a picture in the vertical and horizontal directions and a means decreasing a movement coefficient. CONSTITUTION:An output of a subtractor 34 being a one-frame difference signal is inputted to a control section. An output of a movement detection circuit 40 is mixed with an output from a squaring device 42 by a subtractor 44, a multiplier 46 and an adder 48. A divider 54 obtains V/H from an output V of a vertical change detection circuit 52 and an output H of a horizontal change detection circuit 50 and inputs it to a multiplier 46 via a nonlinear transforming unit 56. The transforming unit 56 outputs a level of 0.4 in the case of the V/H being 1/2 or less, a level of 1 in the case of the V/H being 1/2 or over, the value is a consecutive level. Since the output level of the movement detection circuit 40 is between 0-1, the squared value is less without fail except 0 and 1. Through the constitution above, moving picture processing is implemented by the movement detection output in a slight vertical direction and the moving picture processing is hardly caused in the case of a slight horizontal movement and flicker hardly takes place. When the movement is close to a complete movement, it is not much effected of space change and no unsharp is caused even in the case of a rapid movement.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is applicable to equipment that handles images such as television receivers. It relates to the scanning line interpolation method used during conversion.

[Prior Art] Currently, the standard television system commonly used in television broadcasting, etc. is an incremental signal. It has been thinned out. In this case, the spatio-temporal frequency band that can be transmitted is one that matches visual characteristics in terms of temporal frequency and vertical frequency. However, the spatio-temporal frequency band of the signal source is not necessarily appropriately limited, and the band limitation by the receiver or vision is not sufficient, so the signal contains many aliased components. Therefore, the vertical high-frequency component becomes a temporal high-frequency aliasing component, which causes visual disturbance as flicker. As a result, the vertical resolution in the ink race is only about 70% of the original.

Motion adaptive scanning line interpolation is a means to solve this problem. This means that the image displayed on the monitor is non-inklace, and the scanning lines thinned out by interlacing are
If the image is stationary, interpolate between frames,
This solves the above problem in a stationary area. An example of this is a "signal processing circuit" (Japanese Patent Laid-Open No. 61-32681). This is an interpolated value that is obtained by adding the pixels before and after one frame in the still part, and by adding the pixels above and below in the field in the moving part and dividing the value by 1/2. Since intra-field processing is performed in areas where the image is moving due to motion detection, double images etc. do not occur.

A specific method for motion detection is the "sequential scanning interpolation method" (Japanese Patent Application Laid-Open No. 63-304782) by the present inventor.
There is a method like this. This method combines a nonlinear circuit and a spatio-temporal filter so that it is not concerned with noise or minute movements in the image, and can detect a wide range of movement even if its level is small.

Such scanning line interpolation is used not only for non-interlacing, but also for converting the number of scanning lines from NTSC to HDTV.

[Problems to be Solved by the Invention] When scanning lines are interpolated, even a slight shift in vertical edges (vertical lines) can cause jaggedness or motion blur, so it is better to use video processing as much as possible. On the other hand, when a horizontal edge (horizontal line) moves less than 1/2 pixel, it is likely to cause flicker if it is processed as a moving image, so it is better to process it as a still image.

However, in the conventional example, switching between still image processing and moving image processing is determined by changes in the time direction, and is not related to whether the image changes in the vertical direction or the horizontal direction. In this way, since it does not handle differences in spatial changes, increasing the basic sensitivity will immediately result in video processing, which tends to cause line flickers on horizontal edges, and conversely, lowering the sensitivity will easily cause vertical edges to become jagged. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a motion adaptive scanning line interpolation device that does not cause line flicker or jaggedness even when the sensitivity of switching between still image processing and moving image processing is increased when performing scanning line interpolation.

[Means for Solving the Problems] In order to achieve the above objectives, the present inventors provide the following five methods.

■A method that detects both vertical and horizontal changes and weakens the motion detection signal when the vertical change is large compared to the horizontal direction ■Detects vertical changes and detects motion if they are large A method of weakening the signal ■ A method of detecting changes in the horizontal direction and weakening the motion detection signal when the change is small ■ A method of passing a vertical LPF before motion detection ■ A spatial filter that does not detect spatial changes and uses motion detection Method of making taps vertically elongated In each of the above methods, ■ to ■ use spatial change detection. ■
is the most accurate method, and ■ and ■ are simplified versions of it. In terms of characteristics, the order of ■, ■, and ■ is desirable, but the circuit realization becomes easier in the order of ■, ■, and ■. (2) uses a vertical LPF, (2) does not use these methods, and is simply implemented.

Methods (1) to (2) adaptively mix two motion detection signals with different sensitivities using a control signal obtained from spatial change detection.

In the conventional example of motion detection, the range of taps in the vertical direction of the spatial filter is larger than that in the horizontal direction.
There are 3 taps x 3 taps horizontally (tap intervals are approximately equal).

Therefore, the present invention provides five aspects corresponding to the above five techniques. That is, the first method is implemented by means for obtaining an intra-field interpolated value from an interlaced television signal, a means for obtaining an inter-field interpolated value, and a method for detecting the motion of an image in the interlaced television signal. In a motion adaptive scanning line interpolation device comprising means for generating a coefficient and means for mixing the intra-field interpolated value and the inter-field interpolated value while controlling a mixing ratio according to the motion coefficient, the motion of the image is detected. The means for generating a motion coefficient includes a circuit for detecting a motion of an image, a circuit for detecting a change in the vertical direction of the image, a circuit for detecting a change in the horizontal direction of the image, and a circuit for detecting a change in the horizontal direction of the image. There is provided a motion adaptive scanning line interpolation device characterized in that it comprises means for controlling an output signal of the circuit for detecting motion of the image to reduce the motion coefficient when the motion coefficient is larger than the change in the motion coefficient. Further, means for creating motion coefficients for realizing the second to fifth methods are each configured as follows.

Second method...The means for creating a motion coefficient consists of a circuit that detects the movement of an image, a circuit that detects a change in the vertical direction of the image, and when the change in the vertical direction is larger than a predetermined value, the movement of the image The motion coefficient is controlled by controlling the output signal of the circuit for detecting the motion coefficient.

Third method...The means for creating a motion coefficient includes a circuit that detects the movement of an image, a circuit that detects a change in the horizontal direction of the image, and when the change in the horizontal direction is smaller than a predetermined value, the and means for reducing the motion coefficient by controlling an output signal of a circuit for detecting the motion of the motion coefficient.

Fourth approach: the means for generating motion coefficients comprises a vertical low-pass filter and a circuit for detecting image motion in response to its output signal.

Fifth method...The means for creating a motion coefficient includes a circuit that converts the time difference signal of the interlaced television signal into an absolute value, and a spatial coefficient responsive to the signal converted into an absolute value by the circuit that converts the time difference signal into an absolute value. The present invention includes a circuit for detecting movement of an image having a pass-pass filter whose limited band is narrower in the vertical direction than in the horizontal direction.

[Operation] In the first method with the above configuration, since the vertical change in vertical machining/nozzing is larger than the horizontal change, even if the output of motion detection is small, it becomes a moving image process, and jaggedness and blurring are less likely to occur. On the other hand, in horizontal machining and sawing, it is difficult to process moving images due to minute movements, and line flickers are less likely to occur. Furthermore, if the motion detection is close to complete motion, the effect of spatial changes will be less, and intense motion will not cause double images or dynamic blur. Spatial changes are determined by the vertical-to-horizontal ratio, so they are controlled by the shape rather than the magnitude of the change.

The operations of the second and third methods are basically the same as the first method, but since they are controlled by the magnitude of only one of them, the processing is influenced by the degree of change.

The fourth method uses a vertical LPF on the difference signal before motion detection.
By passing the light through, vertical high-frequency components are suppressed, and sensitivity to images changing in the vertical direction is reduced.

The operation of the fifth method is slightly different from each of the above methods.

When comparing vertical edges and horizontal edges, the vertical edge changes by 5 out of 15 pixels even with the same 1 pixel movement, but the horizontal edge only changes by 3 out of 15 pixels, which is higher than the vertical edge. Becomes sensitive. However, in this method, the spatial modulus of motion is also biased according to the filter configuration, which causes a problem in motion detection operation.

[Embodiment] An embodiment of the motion adaptive scanning line interpolation device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment that implements the first method described above.

In the embodiment shown in FIG. 1, the configuration other than the control section was invented by the present inventor, and a patent application was filed in Japanese Patent Application Laid-Open No. 63-30.
"Progressive scanning interpolation method" described in Publication No. 4782
is the same as

The interlaced television signal input from the signal input terminal 10 is transmitted through a field (262H) delay device 12, a line (H) delay device 14, and a field (262H) delay device 1.
8, a signal delayed by one frame is obtained. The output of the field delay device 18 and the input value are input to a subtracter 34 to obtain a one frame difference signal as an output signal. The output of the subtracter 34 is used in the control section.

On the other hand, the output of the field delay device 12 and the line delay device 14
An intra-field interpolated value is obtained by adding the outputs of , using an adder 16 and halving the addition result.

At the same time, an adder 20 adds the output of the field delay device 18 and the input signal and halves the addition result to obtain an inter-field interpolated value. For both interpolated values, the output of the adder 16 is input to a delay compensator 22, and the output of the adder 20 is input to a delay compensator 24, in order to compensate for a delay occurring in a control section to be described later.

The output of the delay compensator 22 is input to the subtracted input of the subtracter 26, and the output of the delay compensator 24 is input to the subtraction input of the subtracter 26. Next, the output of the subtracter 26 is multiplied by a control signal of 0 to 1 in a multiplier 28, and the product is input to an adder 30. This input is added to the output of the delay compensator 24 in the adder 30 to obtain an interpolated value, which is output from the interpolated value output terminal 32. Here, when the motion coefficient is 0 (stationary), the output of the multiplier 28 is 0, so the delay compensator 24 which is the inter-field interpolated value
The output of the delay compensator 24 is the interpolated value, and if the motion coefficient is 1 (motion), the output of the multiplier 28 is the same as the output of the adder 26, so the output of the delay compensator 24 is the interpolated value.
They cancel each other out by 0, and the output of the delay compensator 22, which is an intra-field interpolated value, becomes the interpolated signal as it is. When the motion coefficient is between O and 1, the intra-field interpolated value and the inter-field interpolated value are mixed at a mixing ratio proportional to the motion coefficient to form an interpolated value.

In an actual television receiver, a non-increment signal is obtained by time-compressing the interpolated scanning lines and the originally existing scanning lines to alternately form scanning lines.

Next, the operation of the interpolation control section, which is a feature of the present invention, will be explained. The output of the subtracter 34, which is a one-frame difference signal, is input to a motion detection circuit 40, a vertical change detection circuit 52, and a horizontal change detection circuit 50.

The motion detection circuit 40 is similar to that shown in the above-mentioned "progressive scanning interpolation method", and an example of its configuration is shown in FIG. The frame difference signal is first converted into an absolute value by an absolute value converter 72, and then provided to a first nonlinear converter 74. The converted signal is detected by the maximum value detector 80 in the field (262H
) Delay device 76 and line (H) delay device 78 determine the maximum value between the signals delayed by 262H and 263H.

After passing through the spatial LPF 82, the second nonlinear converter 84 outputs 0 if the image is still, and 1 at maximum if the image is moving, as a motion detection value. The output of the motion detection circuit 40 is output to a subtracter 44, a multiplier 46, and an adder 48, and a squarer 4
It is mixed with its square value output from 2. This processing operation is similar to the operation of adders 26, 30 and multiplier 28 in the interpolation signal formation described above.

The vertical change detection circuit 52 and the horizontal change detection circuit 50 are disclosed in the patent application “Adaptive Luminance Signal Color Signal Separator” (
Similar to JP-A-1-162493), the difference in change in the vertical or horizontal direction is determined.

For the output signal V of the vertical change detection circuit 52 and the output signal H of the horizontal change detection circuit 50, V/H is determined by the divider 54, converted by the nonlinear converter 56, and then input to the multiplier 46. The conversion characteristics of the nonlinear converter 56 are shown in FIG. 3, and it becomes 1 when V/H is 1/2 or less and 0.4 or more, and outputs a continuous value during that time. Therefore, V is 1/ of H
If it is 2 or less, the control signal is the motion detection as is, and if it is 4 or more, the square value becomes the control signal. Since the output of the motion detection circuit 40 is between O and 1, its square value is always small except when it is O and 1, and the control signal does not change when it is completely still or when it is a moving image, but otherwise the V/H is As it gets bigger, it gets smaller.

In forming such a control signal, whereas motion detection is used as is for control, the control value only becomes smaller, not larger. Therefore, the basic sensitivity of motion detection is set higher than before.

Next, an embodiment that implements the second method will be described. This embodiment is a simplified version of the embodiment shown in FIG. 1, in which spatial detection by the control section is limited to vertical change detection. The configuration of the control section is shown in FIG. 2(a). In the case of only vertical change detection, the vertical change detection is directly input to the nonlinear converter 56'. The characteristics of the nonlinear converter 56' correspond to the case where H is a fixed value in FIG. 3, but the gain is set in accordance with the detection sensitivity. Next, an embodiment for realizing the third method will be described. Like the embodiment shown in FIG. 2(a), this embodiment is a simplified version of the embodiment shown in FIG. ”
The characteristic corresponds to the case where V is a fixed value in FIG. 3, and is in the form of a reciprocal number with respect to the input value H.

Next, an embodiment that implements the fourth method will be described. In this embodiment, a vertical LPF is placed in front of the motion detection circuit 40, and an example of its configuration is shown in FIG. Vertical L in Figure 4
FIG. 5 shows an example of the simplest configuration of the PF58. This LP
At F, the vertical frequency is suppressed with squared cosine characteristics. Since the vertical component of the frame difference signal is suppressed in this way, the detection sensitivity of horizontal edges changing in the vertical direction is lowered.

Next, an embodiment that implements the fifth method will be described. The fifth and simplest method is to configure the control section only with a motion detection circuit and change the configuration of the spatial filter therein. Motion detection circuit 40 shown in FIG.
', the taps of the spatial LPF 82 are increased in the vertical direction and decreased in the horizontal direction. A specific example of the configuration is shown in FIG. FIG. 8 shows the arrangement of pixels used in this case. The band of the LPF is narrow in the vertical direction (widen in the horizontal direction). Figure 7 shows the case where the pixel spacing is almost equal vertically and horizontally, and the horizontal spacing increases when sampling at a frequency system that is four times the color subcarrier. Since the number of taps is approximately halved, the number of taps may be the same both vertically and horizontally.

Although an effect similar to the above method can be obtained by such processing, since the spatial LPF 82 is originally used for smoothing motion detection and regional judgment (majority vote) of motion, in the case of ■ to ■, it is the same as vertical and horizontal. The characteristics of

In FIG. 6, ABS indicates the absolute value conversion circuit 72, NLI and Nl2 indicate the nonlinear converters 74 and 84, and MAX indicates the maximum value detector 80. In FIG. 7, H indicates line ()I) delay device 90.92.94.96, and T indicates pixel delay device 98.1.
Indicates 00.

[Effects of the Invention] As is clear from the above detailed explanation, according to the present invention, changes in the vertical and horizontal directions of an image of an interlaced television signal are detected, and changes in the vertical direction are converted into changes in the horizontal direction. If the change in the horizontal direction is larger than a predetermined value, or if the change in the horizontal direction is smaller than a predetermined value, the motion detection signal is weakened, or the vertical LPF is used before motion detection.
The motion adaptive process in scan line interpolation can be
This is done appropriately for the spatial shape of the image.

Therefore, at vertical edges, even if the output of motion detection is small, it becomes intra-field processing, and jaggedness and blurring are less likely to occur. On the other hand, for horizontal edges, small movements require inter-field interpolation processing, making line flicker less likely to occur.As a result, the effect is that a double-density scan image with less unnaturalness and less resolution loss can be obtained after scanning line interpolation. There is.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a motion adaptive scanning line interpolation device according to a first embodiment of the present invention, and FIGS.
A block diagram showing the control section of the third embodiment, FIG.
A graph showing the nonlinear conversion characteristics of the nonlinear conversion circuit in the figure, FIG. 4 is a block diagram showing the control section of the fourth embodiment,
FIG. 5 is a block diagram showing a configuration example of the vertical LPF in FIG. 4, FIG. 6 is a block diagram showing the motion detection circuit in FIGS. 1, 2, and 4, and FIG. FIG. 8 is a block diagram showing the configuration of the spatial filter in the motion detection circuit in the example. FIG. 8 is a diagram showing pixels used in the spatial filter of FIG. 7. 10...Signal input terminal, 12,18.76...Field delay device, 14,62,64,78,90°92.
94.96...Line delay device, 16,20°30.4
8,66.102,104...Adder, 22.24.
...Delay compensator, 26, 34.44...Subtractor, 28
．． 46... Multiplier, 32... Interpolation signal output terminal, 4
0.40'...Motion detection circuit, 42...Squarer, 5
0... Horizontal change detection circuit, 52... Vertical change detection circuit, 54... Divider, 56.56'56"74
．． 84...Nonlinear converter, 58...Vertical LPF, 7
2...Absolute value conversion circuit, 80...Maximum value detector, 82
... Spatial LPF, 98,100... Pixel delay device. Inventor Kenji Sugiyama
Requester Victor Japan Co., Ltd.

Claims (5)

[Claims] (1) means for obtaining an intra-field interpolated value from an interlaced television signal; means for similarly obtaining an inter-field interpolated value; and means for detecting motion of an image in the interlaced television signal to generate a motion coefficient; In a motion adaptive scanning line interpolation device comprising means for controlling and mixing the intra-field interpolated value and the inter-field interpolated value in accordance with a motion coefficient, the means detects motion of the image and generates a motion coefficient. a circuit for detecting movement of an image, a circuit for detecting a vertical change in the image, a circuit for detecting a horizontal change in the image, and when the vertical change is greater than the horizontal change. , means for controlling an output signal of the circuit for detecting motion of the image to reduce the motion coefficient. (2) means for obtaining an intra-field interpolated value from an interlaced television signal; means for similarly obtaining an inter-field interpolated value; and means for detecting motion of an image in the interlaced television signal to generate a motion coefficient; In a motion adaptive scanning line interpolation device comprising means for controlling and mixing the intra-field interpolated value and the inter-field interpolated value in accordance with a motion coefficient, the means detects motion of the image and generates a motion coefficient. a circuit for detecting image movement; a circuit for detecting a vertical change in the image; and when the vertical change is greater than a predetermined value, controlling an output signal of the image movement detecting circuit. a motion adaptive scanning line interpolation device, comprising means for reducing the motion coefficient. (3) means for obtaining an intra-field interpolated value from an interlaced television signal, means for similarly obtaining an inter-field interpolated value, and means for detecting motion of an image in the interlaced television signal to generate a motion coefficient; In a motion adaptive scanning line interpolation device comprising means for controlling and mixing the intra-field interpolated value and the inter-field interpolated value in accordance with a motion coefficient, the means detects motion of the image and generates a motion coefficient. a circuit for detecting image movement; a circuit for detecting a horizontal change in the image; and when the horizontal change is smaller than a predetermined value, controlling an output signal of the image movement detecting circuit. a motion adaptive scanning line interpolation device, comprising means for reducing the motion coefficient. (4) means for obtaining an intra-field interpolated value from an interlaced television signal, means for similarly obtaining an inter-field interpolated value, and means for detecting motion of an image in the interlaced television signal to generate a motion coefficient; In a motion adaptive scanning line interpolation device comprising means for controlling and mixing the intra-field interpolated value and the inter-field interpolated value in accordance with a motion coefficient, the means detects motion of the image and generates a motion coefficient. A motion adaptive scan line interpolation device comprising a vertical low pass filter and a circuit for detecting image motion responsive to the output signal of the vertical low pass filter. (5) means for obtaining an intra-field interpolated value from an interlaced television signal, means for similarly obtaining an inter-field interpolated value, and means for detecting motion of an image in the interlaced television signal to generate a motion coefficient; In a motion adaptive scanning line interpolation device comprising means for controlling and mixing the intra-field interpolated value and the inter-field interpolated value in accordance with a motion coefficient, the means detects motion of the image and generates a motion coefficient. is a circuit for converting the time difference signal of the interlaced television signal into an absolute value, and a spatial low-pass filter that responds to the signal converted into an absolute value by the circuit for converting into an absolute value, and the limited band is horizontally 1. A motion adaptive scan line interpolation device comprising a circuit for detecting motion of an image that is narrower in the vertical direction.