JPH02105779A - Device for compensating contour of sequential scanning television signal - Google Patents

Abstract

PURPOSE:To maintain a contour compensating effect even when the movement of a displaying picture is large by increasing the synthesizing ratio of the output of a two line contour compensation signal producing section as the movement of the displaying picture increases and dynamically controlling the synthesizing ratio of one line contour compensating signals and two-line contour compensating signals. CONSTITUTION:A one-line contour compensating signal producing section is constituted of cascade-connected two 1-line delaying memories 11b and 11c, an adder and subtractor 13a and 13b, and nonlinear process circuit 15a and a two-line contour compensating signal producing section is constituted of cascaded connected four 1-line delaying memories 11a-11d, an adder and subtractor 14a and 14b, and nonlinear process circuit 15b. In addition, a synthesizing section 16 which synthesizes outputs of the compensating signal producing sections in a changeable synthesizing ratio and a synthesizing ratio controlling section 19 which controls the synthesizing ratio of the section 16 adaptively to the movement of a displaying picture are also provided. The synthesizing ratio of the two-line contour compensating signals is raised as the movement increases. Therefore, a contour compensating effect can be maintained even when the movement of the displaying picture is large.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a contour compensation device for progressive scan television signals used in high-definition television receivers and the like.

(Prior art) High-definition (IDTV, EDTV) television receivers currently under development first convert received television video signals of existing standard formats such as NTSC into digital video signals.
After performing various image quality improvement processes such as /C separation, noise reduction, conversion to progressive scanning, and contour compensation, the signal is converted back to an analog video signal and supplied to the display section.

As shown in FIG. 7, the scan conversion device that performs the above-mentioned conversion to progressive scanning includes delay memories 41, 42, .
43, adder/subtractor 44, 45, 46, 47, coefficient unit 4
8.49, motion detection circuit 50, and time axis compression circuit 51
and converts the interlaced scanning NTSC television signal supplied to the input terminal IN into a progressive scanning television signal with twice the line density and outputting it to the output terminal OUT.
Output to.

Focusing on the pixel signal α appearing at the output terminal of the 262-line delay memory 41, and assuming that it exists on the n-th line of the current field as shown in FIG. The pixel signal β appearing at the output terminal 42 is present on the (n-1)th line one line before in the current field of the interlaced scanning method. Furthermore, the pixel signal T appearing at the output terminal of the 262-line delay memory 43 and the pixel signal δ appearing at the input terminal of the 262-line delay memory 41 include pixel signals α and β, as shown in FIG. These are pixel signals on the n'th line that appear one field before and after the current field, respectively, and appear midway between the nth line and the (n-1)th line of the current field.

That is, if the current field containing pixel signals α and β is an odd field in interlaced scanning, the field containing pixel signal γ is an even field l fields before, and the field containing pixel signal δ is an even field one field later. It is a field.

The adder 44 outputs an interpolated line signal (α+β) generated based on the correlation between adjacent lines, and the adder 45 outputs an interpolated line signal (γ+δ) generated based on the correlation between adjacent frames. . Each interpolated line signal is
In a combining circuit consisting of an adder 46 and coefficient units 48 and 49, the signals are combined by (1-k) at a changeable combining ratio, and the following interpolated line signal ε is generated.

= k(α+β)/2 + (1-k) (γ
+δ)/2・・・・・(1) The motion detection circuit 50 detects the motion in the display screen from the interframe difference signal output from the subtracter 47, and adjusts the coefficient multipliers 48 and 49 according to the detected motion. Control the coefficient value of il
1 to dynamically control the synthesis ratio and (1-k). If there is no movement at all, Equation (1) is set to O, and the interpolated line signal ε is composed only of the component (T+δ)/2 generated based on the correlation between adjacent frames. If there is a large movement, k in equation (1) is set to 1, and the interpolated line signal ε consists only of components (α+β)/2 generated based on the correlation between adjacent lines in the field.

As shown in FIG. 9, the apparatus for performing vertical contour compensation on the progressively scan-converted television signal is composed of cascade-connected l-line delay memories 61, 62 and adders/subtracters 63, 64. has been done. However, the delay time for one line due to line delay memory 61 and 62 is due to the fact that the time axis is compressed in half by progressive scan conversion.
This corresponds to the half-line delay time of the interlaced scanning method. Therefore, if the pixel signal appearing at the input terminal of the 1-line delay memory 61 is the pixel signal of interest α in FIG. The pixel signals ε and β in FIG. In the subtracter 64, half of the output of the adder 63 (
By subtracting α+β)/2, a contour compensation signal for the pixel signal ε, Δε=[ε−(α+β)/2] (2), is generated and output to the output terminal OUT.

(Problem to be Solved by the Invention) When vertical contour compensation is performed using a contour compensation device having the configuration shown in FIG. Accordingly, there is a problem that the effect of contour compensation is lost.

That is, the pixel signal of the interpolation line is mainly composed of components generated based on the correlation between adjacent lines in the field as well as the increase in movement in the display screen. In particular, when there is rapid movement, the pixel signal ε of the interpolated line is a component (α+β)/2 based on the correlation between adjacent lines within the field.
Only.

In this case, the vertical contour compensation signal Δε output from the subtracter 64 in FIG. 9 becomes completely zero, as is clear from equation (2), and the effect of contour compensation is completely lost.

(Means for Solving the Problems) A contour compensation device for a progressive scanning television signal according to the present invention is a one-line contour compensation signal that creates a contour compensation signal from pixel signals of an arbitrary line and each line separated by one line before and after the arbitrary line. Contour compensation signal generator, arbitrary line and 2 lines before and after it
a two-line contour compensation signal generation unit that creates a contour compensation signal from pixel signals of each line separated by a line;
A synthesis section that synthesizes the outputs of the line-to-line contour compensation signal generation section and the two-line contour compensation signal generation section at a changeable synthesis ratio; a combination ratio control unit that controls the combination ratio of the output of the compensation generation unit in a direction to increase;
By dynamically controlling the synthesis ratio of the line-to-line contour compensation signal and the two-line contour compensation signal according to the movement on the display screen, the system is configured to maintain the contour compensation effect even when there is large movement. There is.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a contour compensating device for a progressive scan television signal according to an embodiment of the present invention, where IN is an input terminal for a progressive scan converted television signal, and OUT is an input terminal for a progressive scan television signal. This is an output terminal for a contour compensated progressive scan television signal.

This contour compensation device includes four one-line delay memories lla, llb, llc, and 11d connected in series, adders and subtracters 13a, 13b, 14a, and 14b, and a nonlinear processing circuit 1.
5a and 15b, a synthesis section 16, a horizontal bypass filter 17, adders 18a and 18b, and a synthesis ratio control section 19.

Two cascade-connected 1-line delay memories 11b, ll
c, adder/subtractors 13a and 13b, and nonlinear processing circuit 15
A one-line contour compensation signal generation unit is constructed from a and l.
A contour compensation signal is created from the line of interest appearing between line delay memo 11lb and 11c and the pixel signals of each line separated by one line before and after the line of interest.

That is, the line of interest appearing between the one-line delay memories llb and 110 is the interpolation line n° generated in the progressive scan converter at the previous stage, as shown in FIG.
It is assumed that the above pixel signal ε is now appearing. At this time, the pixel signal α appearing at the input terminal of the 1-line delay memory Ilb and the pixel signal β appearing at the output terminal of the 1-line delay memory IIC are different from each other before interpolation, as shown in FIG. nth and (n-1) in the original field of interlaced scanning method
This is the pixel signal on the th line.

In addition, four 1-line delay memories lla connected in series
, llb, llc, lid, and adder/subtractors 14a, 14b
, and the nonlinear processing circuit 15a constitute a two-line contour compensation signal generation section, and the l-line delay memories llb and ll
A contour compensation signal is created from the line of interest appearing during time c and the pixel signals of each line two lines before and after the line of interest.

In other words, the pixel signal ε° appearing at the output terminal of the 1-line delay memory lid and the pixel signal ε' appearing at the input terminal of the line delay memory 11a are, as shown in FIG. Adjacent interpolation lines before and after ゛ (n'-
1) and the pixel signal on (n'+1). Therefore, 3
The pixel signals ε, ε゛ε′° exist on lines separated by two lines in the field after progressive scan conversion.

■Nonlinear processing circuit 15a of line-to-line contour compensation signal generation section
and the output of the nonlinear processing circuit 15b of the 2-line contour compensation signal generation section are the output of the synthesis ratio that is changed according to the movement in the synthesis section 16, which is composed of coefficient multipliers 16a, 16b and an adder 16c. It is synthesized with. The combination ratio control unit 19 performs a combination that increases the coefficient value k of the combination unit 16 as the movement in the display screen increases, based on the double-speed inter-frame difference signal ΔF supplied to the input terminal (2) from the progressive scan conversion device at the previous stage. Performs motion adaptive control of the ratio.

As shown in the block diagram of FIG. 3, the synthesis ratio control section 19 includes an absolute value circuit 21, three comparison circuits 22a,
22b, 22c, a decoder 23, a coefficient generation circuit 24, and a 1-line delay memory 25a.

25b, 25C, and a maximum value selection circuit 26.

The inter-frame difference signal ΔF supplied to the input terminal l from the progressive scan converter at the previous stage is supplied to one input terminal of each of the three comparison circuits 22a, 22b, and 22c via the absolute value circuit 21. Reference values A, B, and C that increase sequentially are supplied to the other input terminals of the comparison circuits 22a to 22c, and the comparison results x, y, and z are sent to the decoder 23.
supplied to As shown in Figure 4, whether the absolute value of ΔF is less than reference value A, greater than or equal to reference value A and less than B, greater than or equal to reference value B and less than C, or greater than or equal to reference value C. Four types of combinations (xyz) of the comparison results are supplied to the decoder 23 in accordance with the above. (1-k) are output as four types of coefficients that change over the period. With this coefficient (
1-k) are three 1-line value memories 2 connected in cascade.
It is supplied to the maximum value selection circuit 26 via 5a, 25b, and 25c. This maximum value detection circuit selects the largest one of the coefficient values (1-k) and k delayed over three lines and supplies it to the coefficient multipliers 16a and 16b of the combining section 16 in FIG.

As shown in FIG. 4, the coefficient is set to O in a range where the movement on the display screen is minimal. In this case, contour compensation in the vertical direction is performed only by the output of the line-to-line contour compensation signal generator shown in FIG. On the other hand, the coefficient is set to 1 in a range where the movement on the display screen is maximum. In this case, contour compensation in the vertical direction is performed only by the output of the contour compensation signal generation section between the two lines shown in FIG. In a range where the movement on the display screen is intermediate, the coefficient is set to 0.375 or 0°625, and vertical contour compensation is performed using the outputs of the 1-line compensation signal generator and the 2-line contour compensation signal generator. This is done by the composite value of

As shown in the block diagram of FIG. 5, the nonlinear circuits 15a and 15b in FIG. 1 include a sign discrimination circuit 31 and an absolute value circuit 32.
, a coring circuit 33, a slope setting circuit 34, a limiter circuit 35, and an encoding circuit 36. Input terminal I
Concerning the contour compensation signal supplied to the input/output characteristic diagram shown in Figure 6, the contour compensation signal is subjected to nonlinear processing including coring processing for noise removal, slope setting and amplitude limiting processing for adjusting the degree of contour enhancement, etc. is performed, and from the output terminal O to the synthesis section 1
6.

The vertical contour compensation signal output from the combining section 16 is
In the adder 18a, it is added to the pixel signal ξ of interest on the line of interest, resulting in a pixel signal that has been subjected to contour compensation in the vertical direction.

A horizontal contour compensation signal generated by the horizontal bypass filter 17 is added to this pixel signal in an adder 18b, and a progressive scan-converted television signal with contour compensation in both vertical and horizontal directions is generated. Output terminal OU
supplied to T.

As described above, when there is a large movement in the display screen, the vertical contour compensation signal Δε for the target pixel signal ε in FIG.
Contour compensation signal component ε−(ε゛ +ε
”)/2. As shown in Fig. 2, this contour compensation signal component consists of a ring field in which each pixel signal ε, ε゛, ε゛° is sequentially converted into an interlaced scanning ring field before scan conversion. The compensation signal component ε-(α
+β)/2, it does not become O as the movement increases. This results in effective vertical contour compensation even under large movements.

The configuration in which the composition ratio control section 19 for motion adaptive control is installed in the contour compensation device has been described above. However, the composition ratio control section may be configured to be shared with a composition ratio control section for progressive scan conversion installed in the preceding stage progressive scan conversion device.

(Effects of the Invention) As explained in detail above, the contour compensation device of the present invention has the following features:
■An inter-line contour compensation signal generation section, an inter-line contour compensation signal generation section, a synthesis section that synthesizes the outputs of these contour compensation signal generation sections at a changeable synthesis ratio, and a synthesis section that changes the synthesis ratio in this synthesis section. This configuration is equipped with a synthesis ratio control section that performs adaptive control, and increases the synthesis ratio of the two-line contour compensation signal as the motion increases, compared to a conventional configuration that uses a one-line contour compensation signal fixedly. The effect of contour compensation can be maintained even when

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a contour compensation device for progressive scan conversion television signals according to an embodiment of the present invention, and FIG. 3 is a block diagram showing an example of the configuration of the synthesis ratio control unit 19 shown in FIG. 1; FIG. 4 is a conceptual diagram showing an example of the operation shown in FIG. 3; FIG. The figure is a block diagram showing an example of the configuration of the nonlinear processing circuits 15a and 15b shown in FIG. 1, FIG. 6 is a conceptual diagram showing an example of the input/output characteristics of the nonlinear processing circuit shown in FIG. FIG. 8 is a conceptual diagram for explaining the operation of the progressive scan conversion shown in FIG. 7, and FIG. FIG. 2 is a block diagram showing the configuration of a compensation device. IN: input terminal for progressive scan conversion television signal;
lla, tt6. llc, 1ld--1 line delay memory, 13a, 13b, 14a. 14b...Adder/subtractor, 15a, 15b...Nonlinear processing circuit, 16...Composition section, 16...Composition ratio control section, 17...Horizontal bypass filter, OUT...Contour compensation processed television John signal output terminal, 21...
Absolute value circuit, 22a to 22c... Comparison circuit, 23...
- Decoder, 24... Coefficient generation circuit, 25... l line delay memory, 26... Maximum value selection circuit. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (1)

[Claims] An interpolated line signal generated based on the correlation between adjacent lines in a field and an interpolated line signal generated based on the correlation between adjacent frames are dynamically changed according to movement in the display screen. This is an edge compensation device for a motion adaptive progressive scan television signal that is synthesized under a synthesis ratio that creates an edge compensation signal from the pixel signals of an arbitrary line and each line separated by one line before and after the arbitrary line. a line-to-line contour compensation signal generation section that generates a contour compensation signal from pixel signals of an arbitrary line and each line separated by two lines before and after it; a combining unit that combines the outputs of the compensation signal generating unit and the 2-line contour compensation signal generating unit at a changeable combining ratio; and a 2-line contour compensation generating unit that adjusts the combining ratio in the combining unit as the movement in the display screen increases. 1. A contour compensating device for a progressive scan television signal, comprising: a synthesis ratio control section that controls the synthesis ratio of outputs in a direction of increasing it.