JPH11289476A - Contour emphasis circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply effective contour emphasis to a video signal in matching with a visual characteristics of human beings that has a higher sensitivity to a still object than a moving object. SOLUTION: The contour emphasis circuit is provide with a Y signal generating section 12 that generates a Y (luminance) signal from digital R, G, B signals, a contour extract section 13 that extracts a contour component Ye from the Y signal, a motion detection section 30 that detects a motion of an image based on a difference between frames and outputs a contour control signal EC in response to the detected value, a gain control section 31 that multiplies a coefficient in response to the contour control signal EC with a contour component Ye and outputs the product, and contour adder sections 15r, 15g, 15b that add the contour component outputted from the gain control section 31 to the digital R, G, B signals and outputs a video signal whose contour is emphasized. Then as a motion of an image gets smaller, the coefficient multiplied with the contour component Ye extracted by the contour extract section 13 is increased so as to strength the contour emphasis for a still image area more than that for a moving image area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour emphasis circuit for extracting a contour component from a video signal whose contour is to be emphasized, and adding the contour component to the video signal to obtain a contour-enhanced video signal. For example, A / D
There is a signal obtained by converting an analog color video signal into a digital color video signal by an (analog / digital) conversion unit. The analog color video signal includes a composite color video signal or R (red), G (green), There is a B (blue) signal.

[0002]

2. Description of the Related Art As a thin and lightweight display device,
PDP using PDP (plasma display panel)
Attention has been focused on display devices and LCD display devices using LCD (liquid crystal display) panels. Since such a display device is a direct drive system using a digitized video signal, conventionally, when displaying an outline emphasized image,
After an outline-enhanced image signal is obtained by analog signal processing based on the input of an analog color image signal, the image signal is converted into a digital signal by an A / D converter and output to a display device. For this reason, when the amplitude of the input analog color video signal is too large, or when the contour enhancement amount is too large, the analog video signal whose contour is enhanced exceeds the dynamic range of the A / D conversion unit. There is a problem that white and black areas are lost.

The present applicant has already proposed a contour emphasizing circuit as shown in FIG. 9 to solve the above-mentioned problem (PCT / JP97 / 00994). The contour emphasis circuit includes A / D converters 11r, 11g, and 11b for converting analog R, G, and B signals input to input terminals 10r, 10g, and 10b into digital R, G, and B signals. From the R, G, and B signals of FIG.
Signal) (hereinafter simply referred to as a Y signal generator), and a contour component Y from the Y signal.
e, a contour extracting unit 13 for extracting the contour component Ye, adding a contour component Ye to the digital R, G, B signals to enhance the contour (R
+ Ye, G + Ye, B + Ye) to output terminals 14r, 14
g, 14b to be added to the contour adders 15r, 15g, 15
b. The signal processing / phase adjustment unit 16
R output from the / D converters 11r, 11g, 11b,
The G and B signals are subjected to signal processing such as pixel number conversion and gamma correction, and phase adjustment for adjusting a delay difference.

As described above, the A / D converters 11r and 11r
The R, G, and B signals are converted into digital R, G, and B signals by g and 11b.
After conversion into a signal, a Y signal is generated, and the contour component Ye extracted from the Y signal is added to the digital R, G, B signals and output to the display device side. The dynamic range of the A / D converters 11r, 11g, 11b is not exceeded. For this reason,
Even if the analog R, G, and B signals input to the input terminals 10r, 10g, and 10b are large-amplitude signals, or if the amount of edge enhancement is too large, the signals output from the output terminals 14r, 14g, and 14b are converted to digital video. When a contour-enhanced image is displayed by being output to a display device driven by a signal, whiteout or blackout does not occur.

A circuit shown in FIG. 10 (for example, a circuit disclosed in Japanese Patent Application Laid-Open No. 1-318777) is known as a device for controlling the amplitude of a contour component according to the amount of motion to improve image quality. The circuit shown in FIG. 10 separately processes a video signal input to an input terminal 20 in a still area signal processing system 21 and a moving area signal processing system 22, mixes the mixed signal in a mix circuit 23, and outputs the video signal to an output terminal 24. In the output MUSE decoder, a contour signal adding circuit 26 is provided at the subsequent stage of the two-dimensional interpolation filter 25 in the moving area signal processing system 22, and the mixing ratio of the mix circuit 23 and the amplitude of the contour signal are controlled by the motion signal. By doing so, the blur in the moving area of the image is reduced and the image quality is improved.

[0006]

However, in the circuit shown in FIG. 9, even if the video signal (R, G, B signal) is a signal of a moving picture area and a signal of a still picture area, the same contour emphasis is applied. Since the processing is performed, there is a problem that the image quality may be degraded due to insufficient contour enhancement processing for the signal in the still image area. That is, human visual characteristics
This is because the sensitivity to a stationary object is higher than a moving object, and thus it is recognized that the contour enhancement of the still image portion is not appropriate.

In the circuit shown in FIG. 10, an outline signal adding circuit 26 is provided only in the moving area signal processing system 22, and the outline is enhanced only in the moving area of the image, and the outline is enhanced in the still area of the image. As a result, there is a problem that it is not possible to perform effective contour enhancement suitable for human visual characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides an effective contour emphasis suitable for human visual characteristics, in which sensitivity to a stationary object is higher than a moving object. It is an object of the present invention to provide a contour emphasizing circuit capable of performing such operations.

[0009]

According to a first aspect of the present invention, there is provided a contour emphasizing circuit for extracting a contour component from a video signal whose contour is to be emphasized, and for extracting a difference between frames or fields of the video signal. Motion detecting means for detecting a motion of an image based on the image data; gain control means for multiplying a coefficient corresponding to a value detected by the motion detecting means with the contour component extracted by the contour extracting means; and outputting the contour output from the gain control means. A contour adding means for adding a component to the video signal and outputting a video signal whose contour is emphasized, wherein the value of a coefficient multiplied by the contour component when the motion of the image is small is large, and the contour when the motion of the image is large is provided. The value of the coefficient multiplied by the component can be reduced. For this reason, the outline enhancement amount of the still image region is made stronger (for example, 2.750 times) than the outline enhancement amount of the moving image region (for example, the same as that of the proposed circuit), and the effective outline enhancement suitable for human visual characteristics is achieved. It can be performed.

According to a second aspect of the present invention, when the input signal is an analog video signal and the video display device is a display device driven by a digital video signal, the input analog video signal has a large amplitude. Even in the case of a signal or when the amount of contour enhancement is too large, a video signal whose contour is to be enhanced is converted into an analog color signal by an A / D converter in order to prevent the occurrence of overexposure and underexposure in the contour-enhanced image. The video signal is converted into a digital color video signal,
A luminance signal generating means for generating a luminance signal from an output signal of the A / D conversion means is provided. The contour extracting means extracts a contour component from the luminance signal generated by the luminance signal generating means. Detect the motion of the image based on the difference between the frames or fields of the generated luminance signal,
The contour adding means adds the contour component output from the gain control means to the output signal of the A / D conversion means.

According to a third aspect of the present invention, in order to simplify the configuration of the motion detecting means, the motion detecting means extracts the difference between frames of the luminance signal generated by the luminance signal generating means. Frame difference extracting means, and an absolute value converting means for converting the difference extracted by the frame difference extracting means into an absolute value.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the motion detecting means includes:
High frequency component removing means for removing high frequency components from the output signal of the absolute value converting means is provided.

According to a fifth aspect of the present invention, a decoder for decoding an output signal of the high-frequency component removing means is provided in the motion detecting means in order to reduce a change range of a signal handled by the gain controlling means.

The invention according to claim 6 is the invention according to claims 1, 2, 3, and 4.
Alternatively, in the invention according to the fifth aspect, in order to simplify the configuration of the gain control means, the gain control means is generated by a coefficient generation means for generating a coefficient corresponding to a detection value detected by the motion detection means, and the coefficient generation means. Multiplication means for multiplying the coefficient by the contour component extracted by the contour extraction means and outputting the result.

According to a seventh aspect of the present invention, in accordance with the sixth aspect of the present invention, the coefficient generating means is provided with a detection value detected by the motion detecting means in order to increase a degree of freedom of a value generated by the coefficient generating means. Is an address input, and a coefficient is output as a content of the address in a look-up table.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an outline emphasizing circuit according to the present invention, and the same parts as those in FIG. In FIG. 1, 11
r, 11g, 11b are A / D converters, 16 is signal processing
The phase adjustment units, 15r, 15g, and 15b are contour addition units,
2 is a Y signal generation unit, 13 is a contour extraction unit, 30 is a motion detection unit, and 31 is a gain control unit.

The A / D converters 11r, 11g, 11b
Converts analog R, G, and B signals input to the input terminals 10r, 10g, and 10b into digital R, G, and B signals with a resolution of 8 bits and outputs the signals. The signal processing / phase adjustment unit 16 includes the A / D conversion unit 11r,
The R, G, and B signals output from 1g and 11b are subjected to signal processing such as pixel number conversion and gamma correction, and are output after phase adjustment for adjusting a delay difference. The Y signal generator 12 generates a Y signal from digital R, G, and B signals output from the A / D converters 11r, 11g, and 11b. This Y signal generation unit 12 is, for example, an LUT (Look
Up Table) so as to satisfy the following equation (1).
The following equation (2) is satisfied by a method of obtaining a Y signal by adding the R, G, and B signals at a mixture ratio defined by the TSC (National Television System Committee) standard, or by performing bit shift addition as shown in FIG. This is realized by a method of obtaining an approximate value of the Y signal. Y = (0.3 × R) + (0.59 × G) + (0.11 × B) (1) Y ≒ 0.3125 × R + 0.5625 × G + 0.1250 × B (2)

The motion detecting section 30 determines whether the Y signal generated by the Y signal generating section 12 is between frames (or between fields) based on a difference between frames (or between fields) of the Y signal.
The motion of the image is detected. Specifically, as shown in FIG. 3A, the frame difference extraction unit 32 and the absolute value conversion unit 3
3. An LPF (low-pass filter) 34 as a high-frequency component removing unit and a decoder 35. The frame difference extraction unit 32 converts the input 8-bit Y signal into 1
One frame memory 36 for delaying by one frame,
A subtractor 37 calculates and outputs a difference between the Y signal of one frame before and the Y signal of the current frame delayed by the frame memory 36.

The absolute value converter 33 converts the signal output from the subtractor 37 into an absolute value and outputs the absolute value.
The decoder 34 removes high frequency components (noise components) from the signal output from the absolute value converter 33 and outputs the signal.
Is based on the input / output characteristics shown in FIG.
8-bit signal output from F34 (0 in hexadecimal notation)
0 to FF) input, a 3-bit contour control signal E
C (7 to 0 in hexadecimal notation) is output. That is, the contour control signal EC output from the decoder 35 has a smaller value as the value input to the decoder 35 is larger (the motion is larger). For example, if the input value is 00 (for a still image)
EC (output value) when less than 20 (when the amount of motion is small)
When the input value is 80 or more and less than A0, the EC is 3, and when the input value is E0 or more and FF (when the amount of motion is maximum), the EC is 0.

The gain controller 31 multiplies the contour component Ye extracted by the contour extractor 13 by a coefficient corresponding to the contour control signal EC output from the motion detector 30 and outputs the result. Specifically, as shown in FIG.
(Lookup table) 40 and a multiplier 41,
The LUT 40 previously stores data as shown in FIG. That is, when the contour control signal EC (for example, 4) output from the decoder 35 is input, this EC is used as an address and the content (for example, 2.000) is output as a gain. The multiplier 41 multiplies the contour component Ye extracted by the contour extraction unit 13 by the gain (for example, 2.000) output from the LUT 40 and outputs the result.

The contour extraction unit 13 is configured as shown in FIG. 5, similarly to the case of the already proposed proposal shown in FIG.
In FIG. 5, reference numeral 46 denotes a Y signal input terminal, and 48 and 50.
Represents first and second line memories as one-line delay elements,
52 is a vertical contour extraction circuit, 54 is a contour emphasis frequency setting circuit, 56 is a horizontal contour extraction circuit, 58 is a gain controller for a vertical contour component, 60 is a gain controller for a horizontal contour component, 62 is a contour synthesis circuit, and 64 is a coring. circuit,
66 is a gain controller.

The first and second line memories 48 and 50
Generates and outputs a Y signal obtained by sequentially delaying the Y signal input to the input terminal 46 by one line (one scanning line). The vertical contour extraction circuit 52 adds the Y signal input to the input terminal 46 and the two-line delayed Y signal output from the second line memory 50 and outputs the result.
8, a multiplier 70 for multiplying the output signal of the adder 68 by a coefficient (1/4) and outputting the result, and the first line memory 48
A multiplier 72 for multiplying the one-line-delayed Y signal output from the controller by a coefficient (係数) and outputting the same, and a subtractor 74 for subtracting the output signal of the multiplier 70 from the output signal of the multiplier 72
It consists of

The contour emphasizing frequency setting circuit 54 is a circuit for setting the contour emphasizing frequency to a predetermined frequency (for example, 1/2 of the sampling frequency Fs), and sequentially converts the Y signals output from the first line memory 48. 1 dot (1
Four 1-dot delay elements D1 to D4 for delaying pixels)
And a 5-tap type. Each of the one-dot delay elements D1 to D4 is, for example, a D-FF (D
Type flip-flop). The outline emphasis frequency setting circuit 54 is not limited to the 5-tap type, but includes six 1-dot delay elements D1-D connected in series.
It may be a 7-tap type consisting of six. The horizontal contour extraction circuit 56 includes an adder 76 for adding the Y signal output from the first line memory 48 and the 4-dot delayed Y signal output from the fourth 1-dot delay element D4. A multiplier 78 for multiplying the output signal of 76 by a coefficient (１ ／) and outputting the result, and a multiplication of the Y signal of two-dot delay output from the second 1-dot delay element D2 by a coefficient (１ ／) for output And a subtractor 82 for subtracting the output signal of the coefficient unit 78 from the output signal of the coefficient unit 80.

The gain controller 58 multiplies the vertical contour component extracted by the vertical contour extraction circuit 52 by an adjustable coefficient Kv and outputs the result. The gain controller 6
0 is output by multiplying the horizontal contour component extracted by the horizontal contour extraction circuit 56 by an adjustable coefficient Kh. The outline synthesizing circuit 62 synthesizes and outputs the outline components output from each of the gain controllers 58 and 60.

The coring circuit 64 is used to remove noise and minute contour components.
And outputs a contour component which is less than a certain level of the inputted contour component. The coring circuit 64 has, for example, input / output characteristics as shown in FIG. Specifically, when the contour component input from the contour synthesizing circuit 62 is a positive value larger than 0, −δ (δ is a positive constant) is added to the original component and output. And outputs the result, and when the operation result is equal to or more than -δ and equal to or less than + δ, the output is fixed to 0. The gain controller 66 multiplies the contour component output from the coring circuit 64 by an adjustable coefficient K1 and outputs the result to an output terminal 88.

Next, the operation of FIG. 1 will be described with reference to FIGS. A. First, a description will be given of an operation in which the outline enhancement amount of the still image region is made stronger than the outline enhancement amount of the moving image region to perform effective outline enhancement suited to human visual characteristics.

(1) The analog R, G, and B signals input to the input terminals 10r, 10g, and 10b are input to the A / D converter 1
The signals are converted into 8-bit digital R, G, and B signals by 1r, 11g, and 11b.
Signal processing and phase adjustment, and the contour addition units 15r, 15
g, 15b. (2) The Y signal generation unit 12 includes A / D conversion units 11r and 11r.
A Y signal is generated from digital R, G, B signals output from g, 11b. For example, the Y signal generation unit 12
A Y signal is generated from digital R, G, and B signals by bit shift addition using the circuit of FIG. (3) The contour extraction unit 13 extracts a contour component Ye composed of a horizontal contour component and a vertical contour component from the Y signal (B described later).
Will be described in detail. ).

(4) The motion detecting section 30 detects the motion of the image between frames from the Y signal, and outputs a contour control signal EC according to the motion amount. That is, the difference between the Y signal of one frame before and the Y signal of the current frame is calculated by the frame difference extraction unit 32, converted into an absolute value by the absolute value conversion unit 33, and the LPF 34 removes a high frequency component (noise component). The data is input to the decoder 35. In this decoder 35, FIG.
Based on the input / output characteristics as shown in (b), an 8-bit signal corresponding to the amount of motion is decoded and output as a 3-bit contour control signal EC that decreases as the amount of motion increases.

(5) The gain controller 31 calculates the contour component Ye
And a gain determined according to the contour control signal EC. That is, the contour control signal E from the decoder 35
When C (for example, 4) is input to the LUT 40, the EC is used as an address and the content (for example, 2.000) is output from the LUT 40 as a gain. The contour component Ye extracted by the contour extraction unit 13 is multiplied by the gain (for example, 2.000) output from the LUT 40 by the multiplier 41 and emphasized, and is input to the contour addition units 15r, 15g, and 15b. For example, for the signal in the still image area, the contour control signal EC becomes 7, and the maximum gain 2.750 is output from the LUT 40 to the multiplier 41, so that the amplification factor (gain) for the contour component Ye becomes maximum, and For a signal in a moving area having a large amount, the contour control signal EC becomes 0, and the LUT4
Since the minimum gain of 1.000 is output to the multiplier 41 from 0, the degree of amplification (gain) for the contour component Ye is minimized.

(6) Contour adders 15r, 15g, 15b
Then, the R, G, and B signals subjected to the signal processing and phase adjustment by the signal processing / phase adjusting unit 16 and the contour components controlled according to the amount of motion by the gain control unit 31 are added, and the output terminal 1
The image is output to the display device via 4r, 14g, and 14b, and the image with the edge emphasized is displayed on the display device. For this reason, the outline enhancement amount of the still image region can be made stronger than the outline enhancement amount of the moving image region, and effective outline enhancement suited to human visual characteristics can be performed.

B. Next, the input terminals 10r, 10g, 1
A description will be given of an operation in which even when the analog R, G, and B signals input to 0b are large-amplitude signals or when the amount of contour enhancement is too large, whiteout or blackout does not occur in the outline-emphasized image.

(1) The analog R, G, and B signals input to the input terminals 10r, 10g, and 10b are input to the A / D converter 1
The signals are converted into digital R, G, and B signals by 1r, 11g, and 11b, subjected to signal processing and phase adjustment by a signal processing / phase adjusting unit 16, and input to one input side of the contour adding units 15r, 15g, and 15b. (2) The Y signal generation unit 12 includes A / D conversion units 11r and 11r.
A Y signal is generated from digital R, G, B signals output from g, 11b. (3) The contour extracting unit 13 extracts a contour component Ye composed of a horizontal contour component and a vertical contour component from the Y signal. Next, the extraction operation of the contour component Ye by the contour extraction unit 13 will be described in the fifth.
This will be described with reference to the drawings.

(4) First, the operation of extracting a horizontal contour component will be described with reference to FIG. In FIG. 7, vertical lines S1, S2, S3, S4, and S5 represented by dotted lines represent sampling points of respective pixels that are continuously arranged in a horizontal direction along a scanning line including a pixel to be processed. Edge emphasis frequency setting circuit 5
Assuming that the Y signal output from the second 1-dot delay element D2 of FIG. 4 is as shown in FIG. 7A, the signal output from the multiplier 80 of the horizontal contour extraction circuit 56 is as shown in FIG. ) Is input to the + side of the subtractor 82. The Y signal output from the first line memory 48 and the Y signal output from the fourth one-dot delay element D4 of the contour emphasis frequency setting circuit 54 are added by the adder 76 of the horizontal contour extraction circuit 56 to be multiplied. The signal is multiplied by で in the subtractor 78 and input to the minus side of the subtractor 82 as a signal as shown in FIG. The signal (−) calculated by the subtractor 82 is converted by the gain controller 60 into a coefficient K
The signal is multiplied by h and input to one input side of the contour synthesizing circuit 62 as a signal as shown in FIG.

(5) Next, the operation of extracting a vertical contour component will be described with reference to FIG. 8, vertical lines S1, S2, and S3 represented by dotted lines are pixels on three scanning lines of a scanning line including a pixel to be processed and the preceding and following scanning lines.
This represents sampling points of three pixels arranged along the vertical direction including the pixel to be processed. Assuming that the one-line delayed Y signal output from the first line memory 48 is as shown in FIG. 8A, the signal output from the multiplier 72 of the vertical contour extraction circuit 52 is as shown in FIG. As shown, the signal is input to the + side of the subtractor 74. Y input to input terminal 46
The signal and the two-line delayed Y signal output from the second line memory 50 are added by the adder 68 of the vertical contour extraction circuit 52, multiplied by 乗 算 by the multiplier 70, and
As shown in (c) of FIG.
To the side. The signal calculated by the subtractor 74 (−
) Is multiplied by the coefficient Kv by the gain controller 58 and converted into a signal as shown in FIG.
2 to the other input side.

(6) A signal representing a horizontal contour component output from the gain controller 60 and the gain controller 58
The signal representing the vertical contour component output from the signal is synthesized by the contour synthesizing circuit 62, the contour component below a certain level is suppressed by the coring circuit 64 to eliminate the influence of noise, and is multiplied by the coefficient K 1 by the gain controller 66. The level is adjusted and output to the output terminal 88.

(7) The contour component Y output to the output terminal 88
The gain e is controlled by the gain control unit 31 in accordance with the amount of motion of the image, and is input to the other input side of the contour addition units 15r, 15g, and 15b. Therefore, the contour adding unit 15
R, G, B with edge enhancement by addition of r, 15g, 15b
The signal is output to the display device via the output terminals 14r, 14g, and 14b, and the image with the edge emphasized is displayed on the display device. At this time, the horizontal component of the signal output to the output terminal 14r is as shown in FIG. 7 (e), and the vertical component is as shown in FIG. 8 (e). FIG. 7,
Rh and Rv indicated by two-dot chain lines in (e) of FIG. 8 represent horizontal and vertical components of the R signal output from the signal processing / phase adjustment circuit 32. The horizontal and vertical components of the signal output to the output terminals 14g and 14b are the same as the horizontal and vertical components of the signal output to the output terminal 14r.

(8) As described above, the A / D converter 11
r, 11g, and 11b convert analog R, G, and B signals into digital R, G, and B signals, generate a Y signal, and extract the contour components extracted from the Y signal into original digital R, G, and B signals. Since the signal is added to the signal, the contour emphasizing component does not exceed the dynamic range of the A / D converter as in the conventional example. Therefore, even if the analog R, G, and B signals input to the contour emphasizing circuit of the present invention are large amplitude signals or the amount of contour emphasizing is large, the signal output from the contour emphasizing circuit of the present invention is converted to digital R, G, and B signals. A display device driven by G and B signals (for example, a dot matrix type P
When the image is output to the DP display device and the image is displayed, no white or black loss occurs.

In the above-described embodiment, the case where the coefficient generating means is constituted by the LUT in order to increase the degree of freedom of the values generated by the coefficient generating means, but the present invention is not limited to this. Instead, any device may be used as long as it generates a coefficient corresponding to the detection value detected by the motion detection means. For example, instead of an LUT, a constant α (for example, α = 0.
2) and an adder for adding a constant constant β (for example, β = 1) to the output signal of the multiplier, and the output of the adder may be used as a coefficient. In this case, for a signal in a still image area where the amount of motion is the smallest, the coefficient (α × EC + β) to be multiplied by the contour component Ye is the maximum (2.4 because EC = 7), and a signal in a moving image area where the amount of motion is close to the maximum. Is a coefficient multiplied by the contour component Ye (α × EC + β)
Is minimum (1 because EC = 0).

In the above embodiment, in order to simplify the configuration of the gain control means, the gain control means is provided with a coefficient generation means for generating a coefficient corresponding to a detection value detected by the motion detection means, And the multiplication means for multiplying the contour component extracted by the contour extraction means by the contour extraction means and outputting the result. However, the present invention is not limited to this, and the coefficient according to the value detected by the motion detection means is not limited to this. May be multiplied by the contour component extracted by the contour extracting means and output.

In the above embodiment, the case where the motion detecting means is provided with a high-frequency component removing means for reducing the noise component and a decoder for reducing the change range of the signal handled by the gain controlling means will be described. However, the present invention is not limited to this, and may be applied to a system in which one or both of the high-frequency component removing unit and the decoder are omitted.

In the above embodiment, the case where the main part of the motion detecting means is constituted by the frame difference extracting means and the absolute value converting means in order to simplify the structure of the motion detecting means has been described. Is not limited to this, and the motion detecting means may be any device that detects the motion of the image based on the difference between frames (or between fields) of the video signal.

In the above embodiment, when the input signal is an analog video signal and the video display device is a display device driven by a digital video signal, when the input analog video signal is a large-amplitude signal or when the edge enhancement amount is used. In order to prevent overexposure and underexposure from occurring in the contour-enhanced image even when the image is too large, the A / D converter converts the analog color image signal into a digital color image signal. Y signal generation means for generating a luminance signal from the output signal of the A / D conversion means is provided, the contour extraction means extracts a contour component from the Y signal, and the motion detection means sets a signal between frames of the Y signal. (Or between fields), the motion of the image is detected, and the contour addition means adds the contour component output from the gain control means to the output signal of the A / D conversion means. However, the present invention is not limited to this. The contour extracting means for extracting a contour component from a video signal whose contour is to be emphasized, and the motion of an image is detected based on a difference between frames (or between fields) of the video signal. Motion detection means, a gain control means for multiplying a coefficient corresponding to a value detected by the motion detection means with a contour component extracted by the contour extraction means and outputting the result, and adding the contour component output from the gain control means to a video signal. And a contour adding means for outputting a video signal having a contour emphasized therein, wherein the smaller the motion of the image is, the larger the coefficient to be applied to the contour component is to make the contour emphasis amount of the still image region stronger than the contour emphasis amount of the moving image region. In addition, the present invention can be used for a device that performs effective contour enhancement suitable for human visual characteristics.

[0043]

According to the first aspect of the present invention, a contour extracting means for extracting a contour component from a video signal whose contour is to be enhanced, and a motion of an image is detected based on a difference between frames (or between fields) of the video signal. Motion detection means, gain control means for multiplying a coefficient corresponding to a value detected by the motion detection means with the contour component extracted by the contour extraction means and outputting the result, and adding the contour component output from the gain control means to the video signal. Edge addition means for outputting a video signal in which the image is edge-enhanced. The value of the coefficient to be applied to the edge component when the motion of the image is small is increased, and the value of the coefficient to be applied to the edge component when the motion of the image is large is increased. Can be smaller. For this reason, the outline enhancement amount of the still image region is made stronger (for example, 2.750 times) than the outline enhancement amount of the moving image region (for example, the same as that of the proposed circuit), and the effective outline enhancement suitable for human visual characteristics is achieved. It can be performed.

According to a second aspect of the present invention, in the first aspect of the present invention, the video signal whose contour is to be emphasized is a signal obtained by converting an analog color video signal into a digital color video signal by A / D conversion means. A Y signal generation unit for generating a luminance signal from an output signal of the / D conversion unit; a contour extraction unit for extracting a contour component from the Y signal; and a motion detection unit for detecting a difference between frames (or between fields) of the Y signal. Since the motion of the image is detected based on the input signal and the contour adding means adds the contour component output from the gain control means to the output signal of the A / D conversion means, the input signal is an analog video signal, Is a display device driven by a digital video signal, even if the input analog video signal is a large-amplitude signal or the contour enhancement amount is too large, It can be made to shake does not occur.

According to a third aspect of the present invention, in the second aspect, the motion detecting means includes a frame difference extracting means for extracting a difference between frames of the luminance signal generated by the luminance signal generating means, and a frame difference extracting means. And the absolute value conversion means for converting the difference extracted in step (1) into an absolute value, the configuration of the motion detection means can be simplified.

According to a fourth aspect of the present invention, in the third aspect of the present invention, since the high frequency component removing means for removing the high frequency component from the output signal of the absolute value converting means is provided in the motion detecting means, the noise component is reduced. Can be done.

According to a fifth aspect of the present invention, since the decoder for decoding the output signal of the high-frequency component removing means is provided in the motion detecting means, the change range of the signal handled by the gain controlling means can be reduced.

The sixth aspect of the present invention is the first aspect of the present invention.
Alternatively, in the invention according to the fifth aspect, the gain control means includes a coefficient generation means for generating a coefficient corresponding to a detection value detected by the motion detection means, and a coefficient generated by the coefficient generation means multiplied by the contour component extracted by the contour extraction means. And the multiplication means for outputting the signal, the configuration of the gain control means can be simplified.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the coefficient generating means is constituted by a look-up table for inputting an address detected by the motion detecting means and outputting the coefficient as the contents of the address. Therefore, the degree of freedom of the possible values of the coefficients generated by the coefficient generation means can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an outline emphasis circuit according to the present invention.

FIG. 2 is a block diagram illustrating an example of a Y signal generation unit in FIG.

FIG. 3 illustrates an example of a motion detection unit in FIG.
(A) is a block diagram of a motion detection part, (b) is an input / output characteristic diagram of the decoder in (a) figure.

FIG. 4 shows an example of a gain control section in FIG.
3A is a block diagram of a gain control unit, and FIG. 3B is an explanatory diagram of input / output values of an LUT in FIG.

FIG. 5 is a block diagram illustrating an example of a contour extraction unit in FIG. 1;

FIG. 6 is a characteristic diagram of the coring circuit in FIG. 5;

7 (a) to 7 (d) show signal waveforms related to horizontal edge enhancement, and FIG. 7 (a) to FIG.
(E) is a waveform diagram of a horizontal component of a signal output from the output terminal 14r in FIG.

8 (a) to 8 (d) show signal waveforms related to vertical edge enhancement, and FIG. 8 (a) to FIG.
(E) is a waveform diagram of a vertical component of a signal output from the output terminal 14r in FIG.

FIG. 9 is a block diagram of a contour enhancement circuit already proposed by the present applicant.

FIG. 10 is a block diagram of a known edge enhancement circuit.

[Explanation of symbols]

10r, 10g, 10b ... input terminals, 11r, 11
g, 11b... A / D converter, 12... Y signal generator,
13: contour extraction section, 14r, 14g, 14b: output terminal, 15r, 15g, 15b: contour addition section, 16:
Signal processing / phase adjustment unit, 30 ... motion detection unit, 31 ...
Gain control unit 32 Frame difference extraction unit 33
Absolute value converter 34 LPF (an example of high frequency component removing means) 35 Decoder 36 Frame memory
37: subtractor, 40: LUT, 41: multiplier, 4
8, 50: 1-line delay unit, 52: vertical contour component detection unit, 54: contour emphasis frequency setting circuit, 56: horizontal contour component detection unit, 62: contour synthesis circuit, 64: coring circuit, EC: contour control signal R, G, B: an example of a color video signal, Y: a luminance signal, Ye: a contour component.

Claims (7)

[Claims] 1. A contour extracting means for extracting a contour component from a video signal whose contour is to be enhanced, a motion detecting means for detecting a motion of an image based on a difference between frames or fields of the video signal, and the motion detecting means. Gain control means for multiplying the contour component extracted by the contour extraction means by a coefficient corresponding to the value detected by the above-mentioned contour extraction means, and outputting the contour component output from the gain control means to the video signal to enhance the contour of the video signal And a contour adding circuit for outputting a contour. 2. A video signal whose contour is to be enhanced is an analog / video signal.
A luminance signal generating means for generating a luminance signal from an output signal of the analog / digital converting means, the luminance signal generating means being a signal obtained by converting an analog color video signal into a digital color video signal by the digital converting means; The contour component is extracted from the luminance signal generated by the signal generation unit, and the motion detection unit detects the motion of the image based on the difference between the frames or fields of the luminance signal generated by the luminance signal generation unit, The contour adding means converts the contour component output from the gain control means to the analog /
2. The method according to claim 1, wherein the signal is added to an output signal of the digital conversion means.
The described contour enhancement circuit. 3. The motion detecting means includes: a frame difference extracting means for extracting a difference between frames of the luminance signal generated by the luminance signal generating means; and an absolute value for converting the difference extracted by the frame difference extracting means into an absolute value. 3. The contour emphasizing circuit according to claim 2, comprising a converting means. 4. The contour emphasizing circuit according to claim 3, wherein said motion detecting means includes high-frequency component removing means for removing a high-frequency component from an output signal of said absolute value converting means. 5. The contour emphasizing circuit according to claim 4, wherein said motion detecting means includes a decoder for decoding an output signal of said high frequency component removing means. 6. The gain control means includes: a coefficient generation means for generating a coefficient corresponding to a detection value detected by the motion detection means; and a coefficient generated by the coefficient generation means multiplied by a contour component extracted by the contour extraction means. 6. The contour emphasizing circuit according to claim 1, further comprising a multiplying means for outputting. 7. A look-up table wherein the coefficient generating means receives a value detected by the motion detecting means as an input of an address and outputs a coefficient as the contents of the address.
The described contour enhancement circuit.