JPH02122770A - Contour compensating device for sequential scanning television signal - Google Patents

Abstract

PURPOSE:To reduce processing speed for contour compensation to half and to improve compensating accuracy by executing the contour compensation in a vertical direction for respective signals in an original field and in an interpolated field generated from the former one before time base compression for a sequential scanning conversion. CONSTITUTION:Between a motion applicable type interpolating field generating part 2a on a front stage and a time compressing circuit 2b on the rear stage of a motion applicable type sequential scanning converter, a contour compensating device 1 is set, an adder 42 of the generating part 2a averages picture element signals appearing in a delay memory 41b, and generates an interpolating line with the use of a correlation in the field. Further, an adder 43 averages the picture element signal on the line in the previous field of the output terminal of a delay memory 41c and the signal on the same line in the field immediately after the input terminal of a memory 41a, and the interpolating line between the frames is generated. The interpolating line signals are synthesized by coefficient multipliers 34 and 35, which are altered according to motion magnitude, and an adder 36 by the control of a motion detecting/coefficient generating part 38, inputted to an input terminal 12 of the device 1, and the original field signal is inputted to an input terminal 11.

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, HDTV) television receivers currently under development first convert received television video signals of existing standard formats such as rJTsc into digital video signals.
After performing various image quality improvement processes such as Y/C separation, noise reduction, conversion to sequential scanning, and contour compensation, the signal is converted back to an analog video signal and supplied to the display unit.

As shown in FIG. 6, the scan conversion device that performs the conversion to the sequential scan described above includes delay memories 61a and 61 connected in cascade.
b, 61c, adder/subtractor 62, 63°66.67, coefficient unit 64.65, motion detection/coefficient generation circuit 68, and time axis compression circuit 69, and interlace scanning supplied to input terminal IN. The NTSC television signal is converted into a progressive scanning television signal with twice the line density and output to the output terminal OUT.

Focusing on the pixel signal α appearing at the output terminal of the 262-line delay memory 61a, and assuming that it exists on the 2nth line of the current field (assumed to be an even field) as shown in FIG. Stage 1 line delay memory 61
The pixel signal β appearing at the output terminal b exists on the (2n-2)th line one line before in the current field of the interlaced scanning method. In addition, 262 line delay memory 61
The pixel signal γ appearing at the output terminal of C and the pixel signal δ appearing at the input terminal of the 262-line delay memory 61a correspond to one field each for the current field containing the pixel signals α and β, as shown in FIG. Appears before and after (2n-1)
This is the pixel signal on the th line, which appears between the 2nth line and the (2n-2)th line of the current field. In other words, if the current field containing pixel signals α and β is an even field of interlaced scanning,
The field containing the pixel signal γ is an odd field l fields before, and the field containing the pixel signal δ is an odd field one field after.

The adder 62 outputs an interpolated line signal (α+β) generated as the average value of pixel signals on each line in the current field based on the correlation between adjacent lines, and the adder 63 outputs an interpolated line signal (α+β) based on the correlation between adjacent frames. Based on this, an interpolated line signal (T+δ) generated as the average value of pixel signals on the same line in the fields before and after the l field is output. Each interpolation line signal is processed by a synthesis ratio aO and bl which can be changed in a synthesis circuit consisting of an adder 66 and a coefficient multiplier 64.65.
(=1/2-ao), and the following interpolated line signal ε is generated.

ε = a O(α+β)+bl(α+β) ・ ・ ・ ・ ・ (1) The motion detection circuit 68 detects the motion in the display screen based on the interframe difference signal output from the subtracter 67, and By controlling the coefficient values of the coefficient multipliers 64 and 65 according to the movement, the composite ratios aO and bl are dynamically controlled. If there is no movement at all, aO in equation (1) becomes 0 b
l is set to 1/2, and the interpolated line signal ε is composed only of components (γ+δ)/2 generated based on the correlation between adjacent frames. If there is a large movement, aO in equation (1) is set to 1/2 and bl is set to O, and the interpolated line signal ε is a component (
It consists only of α+β)/2.

As shown in FIG. 8, the apparatus for performing vertical contour compensation on the progressively scanned television signal is composed of cascade-connected one-line delay memories 71, 72 and adders/subtractors 73, 74. has been done. However, the delay time of one line due to the one-line delay memory 71 and 72 is due to the time axis being 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 l-line delay memory 71 is the pixel signal α of interest in FIGS. 6 and 7, then
The pixel signals appearing at the input terminal and output terminal of the one-line delay memory 72 correspond to the pixel signals ε and β in FIGS. 6 and 7, respectively. By subtracting half (α+β)/2 of the output of the adder 73 from the pixel signal ε in the subtracter 74, a contour compensation signal for the pixel signal ε, Δε=[ε-(α+β)/2]... ( 2) is generated and output to the output terminal OUT.

(Problems to be Solved by the Invention) The contour compensation device shown in FIG. 8 generates a contour compensation signal for each line in a field that has been sequentially scan-converted from that line and two lines before and after the line. Therefore, the effect of improving image quality becomes more pronounced as the picture on the display screen becomes finer in the vertical direction, but if the picture in the vertical direction is coarser to some extent, the effect of contour compensation becomes smaller.

In addition, the optimal amount of contour compensation for the viewer differs depending on the density of the picture on the display screen, but conventional contour compensation devices do not have adjustment functions to accommodate viewer preferences and lack convenience. There are also problems.

Furthermore, the method in which contour compensation is performed after progressive scan conversion requires twice the processing speed as compared to the case where contour compensation is performed before progressive scan conversion, and there is also the problem that compensation accuracy decreases.

(Means for Solving the Problems) A contour compensating device for a progressive scan television signal according to the present invention performs time axis compression for progressive scan conversion on each of an original field signal and an interpolation field signal generated therefrom. By performing contour compensation in the vertical direction first, the processing speed for contour compensation is reduced by half, and the compensation accuracy is improved.

Furthermore, the contour compensating device of the present invention is capable of detecting each line in one of the interpolation field and the original field, and two adjacent lines in the other field separated by one line before and after the interpolation field.
An inter-line contour compensation signal generation unit that creates a contour compensation signal for each line from the pixel signal of the line, and pixel signals of each line in one field and two adjacent lines in this field separated by one line before and after it. A 2-line contour compensation signal generation section generates a contour compensation signal from the 1-line contour compensation signal generation section and 2-line contour compensation signal generation section synthesizes the outputs of the 1-line contour compensation signal generation section and the 2-line contour compensation signal generation section at a ratio according to a command received from the outside. It is equipped with a variable ratio synthesis means, and is configured to be able to change the band of the contour compensation signal over one octave according to the viewer's preference or the density of the screen.

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, in which 10 is a contour compensation unit for an original field, and 20 is a contour compensation unit for an interpolated field. A compensation unit, I1 is an input terminal for the original field signal to be contour compensated, 30 is a synthesis ratio control unit,
OI is an output terminal for the original field signal which has undergone contour compensation processing.

Further, I2 is an input terminal for an interpolation field signal to be subjected to contour compensation, and 0□ is an output terminal for an interpolation field signal subjected to contour compensation processing.

The contour compensation unit 10 for the original field includes cascade-connected one-line delay memories 11a and 11b, and an adder 12a.
, 12b, subtracters 13a, 13b, and coefficient unit 14,
Nonlinear processing circuits 15a and 15b, synthesis section 16, adder 17, horizontal bypass filter 18, and adder 1
9. Similarly, the contour compensator 20 for the interpolation field also includes a 1-line delay memory 2 connected in series.
1a, 21b, adders 22a, 22b, and adder 23
a, 23b, a coefficient unit 24, a nonlinear processing circuit 25a,
25b, a combining section 26, an adder 27, a horizontal bypass filter 28, and an adder 29. The synthesis ratio control section 30 includes a potentiometer 31 that is operated by a knob, and a voltage A that converts an analog voltage output from the potentiometer into a digital voltage and supplies it to the coefficient multipliers 16a, 16b, 26a, and 26b in the synthesis sections 16 and 26. /D
A converter 32 is provided.

FIG. 2 is a block diagram showing the mutual relationship between the contour compensation device of FIG. 1 and a motion adaptive progressive scan conversion device;
The contour compensator l shown in FIG. 1 is installed between the motion-adaptive interpolation field generation section 2a, which constitutes the front stage of the motion-adaptive progressive scan conversion device, and the time-base compression circuit 2b, which constitutes the rear stage. It shows that there is.

The adder 42 of the interpolation field generation section 2a in FIG.
By averaging pixel signals on adjacent lines appearing at the input/output terminals of the line delay memory 41b, an interpolated line is generated using the correlation between adjacent lines within the field.

The adder 43 also outputs a pixel signal on the line of the immediately previous field appearing at the output terminal of the 262-line delay memory 41c and a pixel signal on the same line of the immediately following field appearing at the input terminal of the 262-line line delay memory 41a. By averaging the pixel signals of , an interpolation line is generated using the correlation between adjacent frames. Both of these interpolated line signals are
Coefficient units 44 and 45 whose coefficients are changed according to the magnitude of movement under the control of the motion detection/coefficient generation unit 48 and the adder 4
6, and is supplied to the input terminal (2) of the contour compensation device 1 as a motion-adaptive interpolation field. On the other hand, the signal of the original field used to generate this interpolated field is supplied to the input terminal (2) of the contour compensator l.

1-line delay memories lla and llb in FIG.

The interval between one line in 21a and 21b corresponds to the interval between one line in the original field before progressive scan conversion. corresponds to the spacing of two lines in the field.

That is, as shown in FIG. 3, the input terminal! .

The original field appearing in is any even field, and the 2nth line L2.1 in this even field
Assume that the pixel signal α arranged in the upper center is appearing between the one-line delay memories lla and llb. At this time,
The pixel signal β on the immediately preceding line L2n-2 in this even field appears at the output terminal of the 1-line delay memory llb, and the pixel signal β on the immediately following line L2n-2 in this even field appears at the input terminal of the 1-line delay memory lla. A pixel signal γ on 2n+Z appears.

On the other hand, pixel signals in the odd field generated from the even original field in the interpolation field generating section 2a at the previous stage and interpolated thereto appear at the input terminal I2. That is, between the l-line delay memo U 21a and 21b, as shown in FIG. A pixel signal δ arranged at the center on 1 appears. At this time, the output terminal of the l-line delay memory 21b is connected to the immediately preceding line Ltn in this odd field.
The pixel signal ε on -2 appears, and the pixel signal ζ on the immediately following line 1-znol in this odd field appears at the input terminal of the one-line delay memory 21a.

In the contour compensation unit 10 for the original field shown in FIG. A line-to-line contour compensation signal generation system is constructed. This two-line contour compensation signal generation system is: l-line delay memories lla and ll
The pixel signal α on the line Lz, which is appearing between the lines b and
Lines L zh-2, L zn separated by two lines (at the time interval within the field after progressive scan conversion) before and after that
A contour compensation signal for the pixel signal α, Δ2α=2α−(β+γ) (3), is generated from the pixel signals β and γ on ol.

Also, a line-to-line contour compensation signal generation system for the original field is constituted by the line delay memory 21a, adder 22a, coefficient unit 14, subtracter 13b, and nonlinear processing circuit 15b. This line-to-line contour compensation signal generation system generates a pixel signal α, a pixel signal δ on lines LKn-1+L2n+1 which are separated by one line before and after within the interpolation field, and therefore a contour compensation signal for the pixel signal α, Δ1α-2α. −(δ+ζ) ... (4) is generated. The two adjacent lines L Kn-1+L znol in the interpolation field where the pixel signals δ and ζ appear are arranged one line apart before and after the line L2n where the pixel signal α appears in the field after progressive scan conversion.

Therefore, the part that generates the contour compensation signal for the pixel signal in the original field from the pixel signals on two adjacent lines in the interpolation field is referred to as the line-to-line contour compensation signal generation system. On the other hand, two adjacent lines arranged before and after an arbitrary line in the original field are arranged with an interval of two lines before and after the field after progressive scanning conversion. Therefore, the part that generates a contour compensation signal for a pixel signal in the original field from pixel signals on two adjacent lines in the original field is referred to as a two-line contour compensation signal generation system.

Both contour compensation signals Δ2α and Δ, α are subjected to nonlinear processing in nonlinear processing circuits 15a and 15b, respectively, and then synthesized in a motion adaptive synthesis circuit 16 at a synthesis ratio according to the magnitude of the motion. Then, a vertical contour compensation signal Δα −(1−kr)Δ, α+krΔ2α . The pixel signal for which this vertical contour compensation process has been completed is added to the horizontal contour compensation signal generated by the horizontal high-pass filter circuit 18 in an adder 19, and is sent to an output terminal connected to a time axis compression circuit. Supplied to O3.

Similarly, the contour compensator 2 for the interpolation field in FIG.
0, one line delay memory 21a connected in cascade
, 21b, adder 22b, coefficient unit 24, and subtracter 2
3a and the nonlinear processing circuit 25a constitute a two-line contour compensation signal generation system for the interpolation field. This 2-line contour compensation signal generation system is based on the interpolation line L2n-1 appearing between the 1-line delay memories 21a and 21b.
The pixel signal δ above and the pixel signal ε on the interpolation line L zn-s + Lz, .

Therefore, the contour compensation signal for the interpolated pixel signal δ, Δ2δ
−26−(ε+ζ) ... (6) is generated.

Further, a 1-line delay memory llb, an adder 12a,
The coefficient unit 24 and the subtractor 23b constitute a line-to-line contour compensation signal generation system for the interpolation field, which generates a pixel signal δ and pixels on interpolation lines LZn-2+LZn separated by one line in the original field before and after the pixel signal δ. signal β,
A contour compensation signal for the interpolated pixel signal δ, Δ1 δ=26−(α+β) (7), is generated from α.

Both contour compensation signals Δ2δ and Δ1 for the interpolated pixel signal δ
After being subjected to nonlinear processing in each of the nonlinear processing circuits 25a and 25b, δ is processed by the motion adaptive synthesis circuit 26.
vertical contour compensation signal Δ δ = (1-kin Δ1 δ + ki Δ2 δ ・ ・ ・
(8) and is added to the pixel signal δ to be compensated in the adder 27. The pixel signal for which this vertical contour compensation process has been completed is added to the horizontal contour compensation signal generated by the horizontal high-pass filter circuit 28 in an adder 29, and is sent to an output terminal connected to a time axis compression circuit. 02.

Nonlinear circuits 15a, 15b, 25 in FIG.
a.

25b, as shown in the block diagram of FIG. 4, is composed of a sign discrimination circuit 51, an absolute value circuit 52, a coring circuit 53, a slope setting circuit 54, a limiter circuit 55, and an encoding circuit 56. Concerning the contour compensation signal supplied to the input terminal ■, coring processing is performed to remove noise as shown in the input/output characteristic diagram in Figure 5, and slope setting and amplitude limiting processing are performed to adjust the degree of contour emphasis. Non-linear processing including this is performed, and the output is supplied from the output terminal O to the synthesis unit 16 or 26.

The vertical contour compensation signal outputted from the combining section 16.26 is converted into pixel signals α,
It is added to δ and becomes a pixel signal that has undergone vertical contour compensation. For this pixel signal, horizontal bypass filter 18.
The horizontal contour compensation signal generated in step 28 is sent to adder 19.
．． 29 and output terminals 0.29 as progressively scan-converted television signals subjected to contour compensation in the vertical and horizontal directions. ．． 02.

A viewer of a television receiver equipped with this contour compensation device can adjust the coefficient kr by operating a knob.

By changing 1-kr, ki, and 1-ki (ki=kr), the contour compensation band can be changed according to the vertical pattern density on the display screen or preference.

(Effects of the Invention) As described in detail above, the contour compensation device for a progressive scanning television signal according to the present invention has a time axis for sequential scanning for each of an original field and an interpolated field generated from this original field. Since the configuration performs contour compensation in the vertical direction prior to compression, the processing speed for contour compensation is reduced by half, and compensation accuracy can be improved accordingly.

Further, the contour compensation device of the present invention includes a one-line contour compensation signal generation section, a two-line contour compensation signal generation section, and changes the ratio of the output of each of these contour compensation signal generation sections according to a command received from the outside. It is equipped with a variable ratio compositing section that performs compositing, and performs contour compensation according to the degree of density in the screen and the viewer's preference. Compared to this, performance is improved and convenience is also improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a contour compensation device for a progressive scan conversion television signal according to an embodiment of the present invention, and FIG. 2 is a mutual relationship between the contour compensation device of FIG. 1 and the progressive scan conversion device. 3 is a conceptual diagram showing the positional relationship on the display screen between the pixel signals appearing in each part of FIG. 1, and FIG. 4 is a block diagram showing the nonlinear processing circuits 15a, 15b,
25a. 5 is a conceptual diagram showing an example of the input/output characteristics of the nonlinear processing circuit shown in FIG. 4. FIG. 6 is a block diagram showing the structure of a conventional progressive scan conversion device. FIG. 7 is a conceptual diagram for explaining the operation of the progressive scan conversion shown in FIG. 6, and FIG. 8 is a block diagram showing the configuration of a conventional contour compensation apparatus for progressive scan conversion television signals. l...Contour compensation device, 2a...Interpolation field generation unit of the progressive scan conversion device, 2b...Time axis compression circuit of the progressive scan conversion device, I...Original field signal to be subjected to contour compensation processing. Input terminal, 12... Input terminal for interpolated field signal to be subjected to contour compensation processing, 10... Contour compensation section for original field signal, 20... Contour compensation section for interpolated field signal, 30... Synthesis ratio control part, 11a, llb, 21a, 2. lb...L line delay memory, 15a, 15b, 25a, 25b--Nonlinear processing circuit, 16.26...Motion adaptive synthesis unit for contour compensation signal, 18.28...Horizontal bypass filter, 0
．． . . . Output terminal for the original field signal that has undergone contour compensation processing, o2 . . .・Vertical contour compensation signal, Δ1α, for the pixel signal δ of the interpolation field
. Δ1 δ...1-line contour compensation signal, Δ2α. Δ2δ・・・Contour compensation signal between two lines. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (1)

[Scope of Claim] A contour compensation device for a progressive scan television signal that performs contour compensation on an original field and an interpolated field generated from the original field prior to time axis compression for progressive scan conversion. a line-to-line contour compensation signal generation unit that generates a contour compensation signal for each line from pixel signals of each line in one field and two adjacent lines in the other field separated by one line before and after the line; Create a contour compensation signal from the pixel signals of each line in the field and two adjacent lines in this field, one line apart before and after it.2
It includes an inter-line contour compensation signal generation section, and a variable ratio synthesis means for synthesizing the outputs of the one-line contour compensation signal generation section and the two-line contour compensation signal generation section at a ratio according to a command received from outside the device. 1. A contour compensation device for a progressive scan television signal, characterized in that: