JPH07115567A - Luminance signal emphasis processing unit - Google Patents

Abstract

PURPOSE:To provide the luminance signal emphasis processing unit in which a transient phenomenon in the middle of an edge is improved, contrast of an impulse signal is enhanced and a pre-overshoot at the surrounding of a step edge with a large amplitude is suppressed. CONSTITUTION:An emphasis signal generating section 1 generates an emphasis signal yi of an input luminance signal xi, an edge signal generating section 2 uses an absolute value of the first derivative of the input luminance signal xi for an edge signal vi, a weighting coefficient calculation section 4 calculates a weighting coefficient ai for each picture element based on the edge signal vi and a coefficient multiplier 5 generates a correction emphasis signal yi' based on the emphasis signal yi and the weighting coefficient ai and a signal adder 3 adds the correction emphasis signal yi' to the input luminance signal xi to generate a luminance signal xi' in which emphasis processing is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance signal enhancement processing device for enhancing a luminance signal in a component video signal.

[0002]

2. Description of the Related Art Conventionally, in a luminance signal emphasizing processing device for emphasizing a luminance signal, for example, as shown in the principle diagram of FIG. An unsharp masking process is performed by adding 20 to form an unsharp masking signal. Further, coring processing for suppressing amplification of noise components is also used. The coring process is a process for preventing addition to the original signal when the value of the second derivative is less than the threshold value, as shown in the input / output relationship of the coring process.

[0003]

In the conventional luminance signal enhancement processing apparatus which employs the unsharp masking method, a pre-overshoot occurring on both sides of a stepped edge having a large amplitude forms an unnatural band area, which is subjective. This is a factor of image quality deterioration. In order to suppress the above-mentioned overshoot, the ratio of the secondary differential value added to the original signal may be reduced, but in this case, two enhancement effects originally possessed by the unsharp masking method, that is, transients at the center of the edge are obtained. The improvement effect and the contrast improvement effect with respect to the impulse-like signal (the signal that immediately falls after rising) are reduced.

Therefore, in view of the problems of the conventional luminance signal enhancement processing apparatus as described above, an object of the present invention is to improve the transient at the center of the edge, improve the contrast of the impulse-shaped signal, and increase the step of large amplitude. It is an object of the present invention to provide a luminance signal enhancement processing device capable of suppressing pre-overshoot in the edge peripheral portion.

[0005]

In order to solve the above-mentioned problems, a luminance signal enhancement processing apparatus according to a first aspect of the present invention includes enhancement signal generation means for generating an enhancement signal y _i from an input luminance signal x _i . Edge signal generating means for calculating the absolute value of the first derivative with respect to the input luminance signal x _i , and using that value as the edge signal v _i of the input luminance signal x _i , and the edge signal generated by the edge signal generating means. v and the weight coefficient calculating means for calculating a weighting factor a _i for each pixel based on the value of _i, enhancement signal generated by the enhancement signal generating means y _i and the weighting factor calculated by the weighting factor calculating means a _i Yes correction enhancement signal 'and correction enhancement signal generating means for generating a correction enhancement signal y _i generated by the correction enhancement signal generating means' y _i to the signal adding means for adding to the input luminance signal x _i from the What will be done It is a feature.

In order to solve the above-mentioned problems, a luminance signal enhancement processing apparatus according to a second aspect of the present invention is the luminance signal enhancement processing apparatus according to the first aspect of the present invention, wherein the weighting factor calculation means is the edge signal. The step edge coefficient calculating means is provided for calculating the step edge coefficient p _i, which decreases in accordance with the distance from the center of the step edge, based on the value of the edge signal v _i generated by the generating means. _The larger the value of _i, the larger the weighting coefficient a _i is.

In order to solve the above-mentioned problems, a luminance signal enhancement processing apparatus according to a third aspect of the present invention is the luminance signal enhancement processing apparatus according to the second aspect of the present invention, wherein the weighting factor calculation means is the edge signal. The impulse signal coefficient calculating means is provided for calculating the impulse signal coefficient q _i according to the ratio of the left and right inclinations of the impulse signal based on the value of the edge signal v _i generated by the generating means.
_The larger the value of _i, the larger the weighting coefficient a _i is.

In order to solve the above-mentioned problems, the luminance signal enhancement processing apparatus according to a fourth aspect of the present invention is the luminance signal enhancement processing apparatus according to the second or third aspect of the invention, wherein the weighting factor calculation means is: Small amplitude signal coefficient calculating means for calculating a small amplitude signal coefficient r _i which becomes a small value in a range desired to be amplified as a small amplitude signal based on the value of the edge signal v _i generated by the edge signal generating means is provided. The weighting coefficient a _i is set to a larger value as the amplitude signal coefficient r _i is smaller.

Further, in order to solve the above-mentioned problems, the luminance signal enhancement processing apparatus according to the fifth aspect of the present invention is the third or fourth aspect.
In the luminance signal enhancement processing device according to the invention described above, the weighting factor calculation means generates a small amplitude signal that can be regarded as noise in the small amplitude signal based on the value of the edge signal v _i generated by the edge signal generation means. The noise coefficient calculating means for calculating the noise coefficient s _i shown in FIG.
_The smaller the value of _i is, the smaller the weighting coefficient a _i is.

[0010]

In the luminance signal enhancement processing device according to the first invention,
The enhancement signal y of the input luminance signal x _i by the enhancement signal generation means
_{In addition} to generating _i , the edge signal generating means calculates the absolute value of the first derivative of the input luminance signal x _i , and uses that value as the edge signal v _i of the luminance signal x _i . Further, the weighting coefficient calculating means calculates the weighting coefficient a _i for each pixel based on the value of the edge signal v _i , and the correction emphasis signal generating means calculates the correction emphasis signal from the emphasis signal y _i and the weighting coefficient a _i. generate y _i '. Then, the corrected emphasis signal y _i ′ is added to the input luminance signal x _i by the signal adding means to generate the luminance signal x _i ′ which has been subjected to the emphasis processing.

Also, in the luminance signal enhancement processing apparatus according to the second invention, in the luminance signal enhancement processing apparatus according to the first invention, the weighting factor calculation means is the step edge coefficient calculation means from the center of the step edge. A step edge coefficient p _i whose value decreases according to the distance is calculated, and the larger the value of the step edge coefficient p _i , the more the weight coefficient a.
_{Let i} be a large value.

Further, a luminance signal enhancement processing apparatus according to a third aspect of the present invention is the luminance signal enhancement processing apparatus according to the second aspect of the present invention, wherein the weighting coefficient calculation means uses the impulse signal coefficient calculation means to calculate the edge signal v _i . The impulse signal coefficient q according to the ratio of the left and right inclinations of the impulse signal based on the value
_i is calculated, and the larger the value of the impulse signal coefficient q _i , the larger the weighting coefficient a _i .

The brightness signal enhancement processing apparatus according to a fourth aspect of the present invention is the brightness signal enhancement processing apparatus according to the second or third aspect of the invention, wherein the weighting factor calculation means is the small amplitude signal coefficient calculation means. calculating a small-amplitude signal coefficients r _i, which becomes a small value in the range that was amplified as a small amplitude signal based on the value of the signal v _i, large and the small amplitude signal coefficient r smaller value the weighting coefficient of the _i a _i The value.

Furthermore, a luminance signal enhancement processing apparatus according to a fifth aspect of the present invention is the luminance signal enhancement processing apparatus according to the third or fourth aspect of the present invention, wherein the weighting coefficient calculation means is a noise coefficient calculation means. Based on the value of _i , a noise coefficient s _i indicating a small amplitude signal that can be regarded as noise in a small amplitude signal is calculated, and the smaller the value of the noise coefficient s _i , the smaller the weighting coefficient a _i .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a luminance signal enhancement processing apparatus according to the present invention will be described in detail below with reference to the drawings.

The luminance signal emphasizing processing apparatus according to the present invention, for example as shown in the block diagram of FIG. 1, an input luminance signal x _i
Are supplied to the edge signal generation section 1, the edge signal generation section 2 and the signal adder 3, the edge signal generation section 2 supplies the edge signal v _i to the weighting coefficient calculation section 4, and the emphasis signal generation section 1 enhanced signal y _i and a coefficient multiplier 5 which weighting factors a _i from the weight coefficient calculation unit 4 is supplied with is supplied, the input luminance signal x _i enhancement signal by said enhancement signal generating unit 1 from y _i from And the edge signal generation unit 2 generates an edge signal v _i , and the weight coefficient calculation unit 4 calculates a weight coefficient a _i for each pixel based on the value of the edge signal v _i , and the coefficient multiplication A correction emphasis signal y _i 'is generated by the device 5 as a product of the emphasis signal y _i and the weighting coefficient a _i as shown in the following equation (1), and the signal adder 3 calculates the following (2) As shown in the equation, the correction emphasis signal y _i 'is By adding to the input luminance signal x _i , the luminance signal x _i ′ that has undergone the emphasis process is generated.

[0017]

## EQU1 ## y _i '= a _i y _i (1)

[0018]

[Expression 2] x _i '= x _i + y _i ' ... (2)

The emphasized signal generator 1, the edge signal
Input luminance signal x supplied to the generator 2 and the signal adder 3
_iIs sampled at equal intervals,
x₁, X ₂, ・ ・ ・, X_NIt is represented by.

The emphasizing signal generator 1 calculates, as the emphasizing signal y _i , a constant multiple of the second derivative of the input luminance signal x _{i according to} the following equation (3).

[0021]

Y _i = α (2.0x _i −x _i-di −x _{i + di} ) (3)

Here, α is a constant, and di represents a delay amount for calculating a differential value (difference value).

The edge signal generator 2 calculates the absolute value of the first-order derivative of the input luminance signal x _{i by} the following equation (4) and outputs the calculated value as the edge signal v _i .

[0024]

[Equation 4]

Further, the weighting factor calculator 4 calculates the weighting factor a _i for each pixel based on the value of the edge signal v _i generated by the edge signal generator 2, and is shown in FIG. 2, for example. As described above, the maximum value detector 11, the step edge coefficient calculator 12, the impulse signal coefficient calculator 13,
It is composed of a small amplitude signal coefficient calculator 14, a noise coefficient calculator 15, and a weighting coefficient calculator 16.

The maximum value detector 11 is supplied with the edge signal v _i generated by the edge signal generator 2, and the following expression (5) for the edge signal v _i
Three types of maximum values vmx shown in equations (6) and (7)
Detect _L , vmx _R , and v _max .

[0027]

[Equation 5]

[0028]

[Equation 6]

[0029]

[Equation 7]

Here, N is the size of the neighborhood, and max
_exp (val) is a function that gives the maximum value of val satisfying exp. That is, vmx _L is the maximum value of the edge signal near the left side of the pixel of interest i,
mx _R represents the maximum value of the edge signal near the right side. Further, v _max represents the maximum edge signal in the vicinity of both sides of the pixel of interest, but in reality, v _{max L} and vmx _R
And the maximum of v _i is chosen. The maximum values vmx _L and vmx _R are supplied to the impulse signal coefficient calculator 13, and the maximum value v _max is the step edge coefficient calculator 12, the small amplitude signal coefficient calculator 14 and the noise coefficient calculator. Is supplied to the container 15.

The step edge coefficient calculator 21 calculates the edge signal v _i generated by the edge signal generator 2.
And the maximum value v _max detected by the maximum value detector 11 are supplied, and the edge signal v _i and the maximum values v on both sides thereof are supplied.
Step edge coefficient p from _{max at} pixel of interest i
_i is calculated by the following equation (8).

[0032]

(8) p _i = v _i / v _max (8)

The step edge coefficient p _i is considered to be an edge signal normalized by the maximum value v _max on both sides. As shown in FIG. 3, the step edge coefficient is 1.
It takes a value of 0 and exhibits a change that approaches 0.0 around the edge. That is, the step edge coefficient p _i is a value indicating how far the target pixel is from the center of the step edge.

Further, the impulse signal coefficient calculator 13, an impulse signal coefficients q _i from the edge signal v left maximum value of _i vmx _L and right maximum vmx _R calculated by the following equation (9).

[0035]

[Mathematical formula-see original document] q _i = min (vmx _R / vmx _L , vmx _L / vmx _R ) (9)

Here, min (a, b) is a function that outputs the smaller of a and b. When there is a step edge in the vicinity of the pixel of interest _i , the left and right maximum values vmx _L and vmx _R of the edge signal v _i are significantly different, and the impulse signal coefficient q _i is a small value. On the other hand, in the case of an impulse-shaped signal, the maximum values on the left and right become substantially equal, so the impulse signal coefficient q _i becomes a value close to 1.0. Therefore, the impulse signal coefficient q _i represents the impulse signal likeness of the input signal. Maximum values vmx _L and vmx in step edge and impulse signal
The relationship between _R and the pixel of interest i is shown in FIG.

Further, in the small amplitude signal coefficient calculator 14, the both side maximum value v _{ma x} edge signals v _i of the following (10)
The small amplitude signal coefficient r _i is calculated by normalizing as in the equation.

[0038]

[Equation 10]

Here, r _min and r _max are constants for normalization, but r _{i in the} range desired to be amplified as a small amplitude signal.
Set so that the value of is sufficiently small.

Further, in the noise coefficient calculator 15,
The noise coefficient s _iTo calculate.

[0041]

[Equation 11]

This formula (11) is formally expressed by the formula (10).
Exactly the same as _min, S_maxThe value of
different. R in equation (10)_iAmong small amplitude signals represented by
Contains a small amplitude signal that can be regarded as noise, and r
_iIf all the small parts of
It will be amplified up to. s_iIs such an increase in noise
This is a coefficient used to reduce the width. Small amplitude signal and fine
To distinguish small amplitude noise, s_min, S_maxIs
Each r_min, R_maxIs set to a smaller value.
The small amplitude signal coefficient r is shown in FIG._iAnd noise factor s_iShows the relationship of
You

Further, the weighting factor calculator 25 calculates the weighting factor a _{i in the} equation (1) from the step edge coefficient p _i , the impulse signal coefficient q _i , the small amplitude signal coefficient r _i and the noise coefficient s _i. It is calculated by the equation (12).

[0044]

[Equation 12]

The expression (12) represents the following (A) to (D). (A) For a noise component whose noise coefficient s _i is small,
The value of the weighting coefficient a _i becomes smaller. The weighting coefficient a _i of the signal component having a large noise coefficient s _i is determined by the expression in brackets {}. (B) The value of the weighting coefficient a _i becomes large for a signal of small amplitude in which the noise coefficient s _i is large and the small amplitude signal coefficient r _i is small (the second term in brackets {}). (C) For a large-amplitude signal having a large noise coefficient s _{i and a} large small-amplitude signal coefficient r _i , when the normalized edge signal (step edge coefficient p _i ) is large, that is, at the center of the step edge. Then, the value of the weighting coefficient a _i becomes large (the first term in curly brackets []). (D) For a large amplitude signal with a large noise coefficient s _{i and a} large small amplitude signal coefficient r _i , the step edge coefficient p _i
Even if is small, the value of the weighting coefficient a _i is large when the value of the impulse signal coefficient q _i is large, that is, when the possibility of an impulse-shaped signal is high (the second term in the curly braces []).

That is, in the weighting factor calculation section 4, the following four conditions (a) to (d) to be realized as the brightness enhancement processing are to be realized.
The weighting coefficient a _i is calculated for each pixel in consideration of the above.

(A) Condition on Step Edge At the center of the step edge, the value of the weighting coefficient a _i is increased to increase the inclination. Further, in the peripheral portion of the step edge, the value of the weighting coefficient a _i is reduced in order to suppress the overshoot (see (a) in FIG. 6). That is, based on the value of the edge signal v _i generated by the edge signal generator 2, the step edge coefficient calculator 1
2 calculates the step edge coefficient p _i that decreases in value according to the distance from the center of the step edge, and the weight coefficient calculator 16 calculates the weight coefficient according to the step edge coefficient p _i according to the equation (12). Change the value of a _i .

(B) Condition concerning impulse signal For an impulse-shaped signal which falls immediately after rising, the value of the weighting coefficient a _i is increased in order to increase the contrast ((b) of FIG. 6). reference). That is, based on the value of the edge signal v _i generated by the edge signal generation unit 2, the impulse signal coefficient calculator 13 calculates the impulse signal coefficient q _i according to the ratio of the left and right inclinations of the impulse signal, The weighting factor calculator 16 changes the value of the weighting factor a _i according to the impulse signal coefficient q _i according to the equation (12).

(C) Condition concerning small amplitude signal For a signal having a small amplitude such that the contrast is insufficient, the value of the weighting coefficient a _i is increased in order to increase the contrast (see (c) of FIG. 6). That is, based on the value of the edge signal v _i generated by the edge signal generation unit 2, the small amplitude signal coefficient calculator 14 calculates a small amplitude signal coefficient r _i that has a small value in the range to be amplified as a small amplitude signal. Then, the weighting factor calculator 16 changes the value of the weighting factor a _i according to the small amplitude signal coefficient r _i according to the equation (12).

(D) Condition concerning noise In order to avoid amplification of a signal having a small amplitude that can be regarded as noise, the value of the weighting coefficient a _i is made small (see (d) of FIG. 6). That is, based on the value of the edge signal v _i generated by the edge signal generation unit 2, the noise coefficient calculator 15 calculates the noise coefficient s _i indicating the minute amplitude signal that can be regarded as noise in the small amplitude signal. The weight coefficient calculator 16 changes the value of the weight coefficient a _i according to the noise coefficient s _i according to the equation (12).

Here, in the above equation (12), the above (B)
As described above, a signal with a small amplitude is unconditionally amplified. As a result, the pre-overshoot is added to the small amplitude step edge, and the condition (a)
Although it seems to contradict with, the amount of overshoot is not so large (unnatural) because the amplitude is small originally. On the contrary, at such a step edge having a small amplitude, it is considered that a slight overshoot may be preferable because the sense of contrast increases.

As described above, the weighting factor calculation unit 4 uses the weighting factor a _i calculated for each pixel in consideration of the above four conditions (a) to (d), so that the transient in the center of the edge is determined. It improves the contrast for impulse-like signals that fall immediately after rising, and improves the contrast for small-amplitude signals that lack contrast, and also improves noise. It is possible to avoid the amplification of a signal having a minute amplitude that can be regarded as, and suppress the pre-overshoot in the peripheral portion of the step edge having a large amplitude.

Further, in the luminance signal enhancement processing device of this embodiment, the coefficient multiplier 5 functions as a correction enhancement signal generating means, and the enhancement signal generation unit 1 according to the above equation (1).
Generating a corrected enhancement signal y _i 'as the product of the weighting factors a _i from the enhanced signal y _i and the weighting coefficient calculation unit 4 from.
Further, the signal adder 3 adds the corrected emphasized signal y _i ′ to the input luminance signal x _i according to the equation (2) to generate the emphasized luminance signal x _i ′.

In the above-described embodiment, the weighting factor calculator 25 considers the above four conditions (a) to (d) and uses the equation (12) to calculate the step edge coefficient p _i , the impulse signal coefficient q _i , Although the weighting coefficient a _i in the above equation (1) is calculated from the small amplitude signal coefficient r _i and the noise coefficient s _{i, the} condition (a) regarding the step edge may be satisfied based on the step edge coefficient p _i in principle. By calculating the weighting coefficient a _i , it is possible to improve the transient at the center of the edge and suppress the pre-overshoot at the periphery of the step edge having a large amplitude.

In the weighting factor calculator 25,
The step edge coefficient p _i and the impulse signal coefficient q
Based on _i , the condition (a) regarding the above step edge
In addition, by calculating the weighting coefficient a _i that satisfies the condition (b) regarding the impulse signal, the transient at the center of the edge is improved, and the impulse-like signal that immediately falls after rising rises. It is possible to improve the contrast and suppress the pre-overshoot around the step edge having a large amplitude.

In the weighting factor calculator 25,
Based on the step edge coefficient p _i and the small amplitude signal coefficient r _i , the weighting coefficient a _i that satisfies the condition (a) related to the step edge and the condition (c) related to the small amplitude signal is calculated. It is possible to improve the transient at the center of the edge and improve the contrast for signals with small amplitude such as lack of contrast, and to suppress the pre-overshoot around the step edge with large amplitude. .

In the weight coefficient calculator 25,
The step edge coefficient p _i and the impulse signal coefficient q _i
And the small amplitude signal coefficient r _i , the weighting coefficient a _i that satisfies the condition (a) related to the step edge, the condition (b) related to the impulse signal, and the condition (c) related to the small amplitude signal may be calculated. For example, it improves the transient at the center of the edge, improves the contrast for impulse-shaped signals that fall immediately after rising, and for small-amplitude signals that lack contrast. It is possible to improve the contrast and suppress the pre-overshoot around the step edge having a large amplitude.

In the weight coefficient calculator 25,
Based on the step edge coefficient p _i , the small amplitude signal coefficient r _i and the noise coefficient s _i , the condition (a) for the step edge and the condition (c) for the small amplitude signal and the condition (d) for noise are satisfied. Weighting factor a
_{If i} is calculated, the transient at the center of the edge is improved, and the contrast is improved for a signal with a small amplitude such as insufficient contrast, and a signal with a small amplitude that can be regarded as noise is obtained. On the other hand, it is possible to avoid the amplification and suppress the pre-overshoot around the step edge having a large amplitude.

Then, in the weighting factor calculator 25, based on the step edge coefficient p _i , the impulse signal coefficient q _i , the small amplitude signal coefficient r _i and the noise coefficient s _i together with the condition (a) relating to the step edge, If the weighting factors a _i that satisfy the condition (b) regarding the impulse signal, the condition (c) regarding the small amplitude signal, and the condition (d) regarding the noise are calculated, as in the above-described embodiment, the edge center portion is calculated. Transients, improve the contrast for impulse-like signals that fall immediately after rising, and improve the contrast for small-amplitude signals that lack contrast. At the same time, avoid amplification of signals with small amplitude that can be regarded as noise, and Pre overshoot of the edge peripheral portion it is possible to suppress feel more alert.

[0060]

As described above, in the luminance signal emphasizing processing device according to the first aspect of the invention, the emphasizing signal generating means generates the emphasizing signal y _i of the input luminance signal x _i , and the edge signal generating means performs the above-mentioned operation. The absolute value of the first-order derivative of the input luminance signal x _i is calculated, and the value is used as the edge signal v _i of the luminance signal x _{i. Further} , the weighting coefficient calculation means calculates each pixel based on the value of the edge signal v _i. A weighting coefficient a _i is calculated, and a correction emphasis signal generating means generates a correction emphasis signal y _i 'from the emphasis signal y _i and the weight coefficient a _i ,
By adding the corrected emphasized signal y _i ′ to the input luminance signal x _i by the signal adding means, it is possible to generate the luminance signal x _i ′ that has undergone the emphasis processing.

Further, in the luminance signal enhancement processing apparatus according to the second invention, in the weighting factor calculation means in the luminance signal enhancement processing apparatus according to the first invention, the distance from the center of the step edge is calculated by the step edge coefficient calculation means. The step edge coefficient p _i that decreases in accordance with the above is calculated, and the larger the value of the step edge coefficient p _i is, the larger the weighting coefficient a _i is. It is possible to suppress the pre-overshoot in the peripheral part of a large step edge.

In the luminance signal enhancement processing apparatus according to the third aspect of the invention, the weighting factor calculation means in the luminance signal enhancement processing apparatus according to the second aspect of the invention uses the impulse signal coefficient calculation means to calculate the value of the edge signal v _i . The impulse signal coefficient q _i is calculated based on the ratio of the left and right slopes of the impulse signal, and the larger the value of the impulse signal coefficient q _i is, the larger the weighting coefficient a _i is. Can be improved, the contrast of the impulse-like signal can be improved, and the pre-overshoot around the step edge with a large amplitude can be suppressed.

Further, in the luminance signal enhancement processing apparatus according to the fourth aspect of the present invention, in the weighting factor calculation means in the luminance signal enhancement processing apparatus according to the second aspect of the invention, the small amplitude signal coefficient calculation means determines the edge signal v _i . based on the value calculated small-amplitude signal coefficients r _i, which becomes a small value in the range that was amplified as a small amplitude signal, to the small-amplitude signal coefficients r _i as the weighting factors a _i value is small and a large value that Due to
It is possible to improve the transient at the center of the edge, improve the contrast of a signal having a small amplitude such that the contrast is insufficient, and suppress the pre-overshoot at the periphery of the step edge having a large amplitude.

Further, in the luminance signal enhancement processing apparatus according to the fourth aspect of the invention, in the weighting factor calculation means in the luminance signal enhancement processing apparatus according to the third aspect of the invention, the edge signal v _i of the edge signal v _i is calculated by the small amplitude signal coefficient calculation means. based on the value calculated small-amplitude signal coefficients r _i, which becomes a small value in the range that was amplified as a small amplitude signal, to the small-amplitude signal coefficients r _i as the weighting factors a _i value is small and a large value that Due to
It improves the transient at the center of the edge, improves its contrast for impulse-like signals that fall immediately after rising, and its contrast for signals of small amplitude where contrast is insufficient. And it is possible to suppress the pre-overshoot around the step edge having a large amplitude.

In the luminance signal enhancement processing apparatus according to the fifth aspect of the present invention, the weighting coefficient calculation means in the luminance signal enhancement processing apparatus according to the third aspect of the invention determines the value of the edge signal v _i by the noise coefficient calculation means. A noise coefficient s _i indicating a minute amplitude signal that can be regarded as noise in the small amplitude signal is calculated based on the noise coefficient s _i , and the smaller the value of the noise coefficient s _i is, the smaller the weight coefficient a _i is. The transient of the part is improved, and the contrast is improved for a signal with a small amplitude such as lack of contrast, and the amplification is avoided for a signal with a small amplitude that can be regarded as noise, and the amplitude of It is possible to suppress the pre-overshoot around the large step edge.

Further, in the luminance signal enhancement processing apparatus according to the fifth aspect of the invention, in the weighting factor calculation means in the luminance signal enhancement processing apparatus according to the fourth aspect, the value of the edge signal v _i is calculated by the noise coefficient calculation means. A noise coefficient s _i indicating a minute amplitude signal that can be regarded as noise in the small amplitude signal is calculated based on the noise coefficient s _i , and the smaller the value of the noise coefficient s _i is, the smaller the weight coefficient a _i is. The transient of the part is improved, the contrast is improved for the impulse-like signal that falls immediately after the rising, and the contrast is improved for the signal of small amplitude where the contrast is insufficient. In addition, avoid amplification of a signal with a small amplitude that can be regarded as noise, and around a step edge with a large amplitude. It is possible to feel more alert the pre-overshoot suppression.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a luminance signal enhancement processing device according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of a weighting factor calculation unit in the luminance signal enhancement processing device.

FIG. 3 is a waveform diagram showing a change state of an edge signal with respect to a step edge.

FIG. 4 is a waveform diagram showing a change state of a right side maximum value and a left side maximum value of an edge signal.

FIG. 5 is a small amplitude signal section calculated by the weighting factor calculation unit.
Number r_iAnd noise factor s _iIt is a figure which shows the relationship of
It

FIG. 6 is a weighting coefficient a _i generated by the weighting coefficient calculation unit.
FIG. 6 is a waveform diagram schematically showing the condition that should be satisfied.

FIG. 7 is a diagram schematically showing the principle of unsharp masking processing in a conventional luminance signal enhancement processing apparatus.

FIG. 8 is a diagram schematically showing the principle of coring processing used together with the above unsharp masking processing in a conventional luminance signal enhancement processing apparatus.

[Explanation of symbols]

 1 ... Emphasized signal generator 2 ... Edge signal generator 3 ... Signal adder 4 ... Weighting factor calculator 5 ... Coefficient multiplier 11. .... Maximum value detector 12 ... Step edge coefficient calculator 13 ... Impulse signal coefficient calculator 14 ... Small amplitude signal coefficient calculator 15 ... Noise coefficient Calculator 16 ... Weighting factor calculator

Claims (5)

[Claims] 1. A input luminance signal x _i and enhancement signal generating means for generating an emphasis signal y _i from the input luminance signal x _i of first derivative of calculating the absolute value, the input luminance signal of the value x _i Of the edge signal v _i, and the edge signal v generated by the edge signal generating means.
a weight coefficient calculating means for calculating a weighting factor a _i for each pixel based on the value of _i, the weighting factor a _i calculated by the enhanced signal y _i and the weighting factor calculating means which is generated by the enhancement signal generating means 'and correction enhancement signal generating means for generating a correction enhancement signal y _i generated by the correction enhancement signal generating means' correction enhancement signal y _i from the and a signal adding means for adding to the input luminance signal x _i A luminance signal enhancement processing device characterized by the following. 2. The weighting factor calculation means calculates a step edge coefficient p _i that decreases in accordance with the distance from the center of the step edge based on the value of the edge signal v _i generated by the edge signal generation means. 2. The luminance signal enhancement processing apparatus according to claim 1, further comprising step edge coefficient calculation means for calculating, wherein the larger said step edge coefficient p _i , the larger said weighting coefficient a _i . 3. The impulse coefficient calculating means calculates an impulse signal coefficient q _i according to a ratio of left and right inclinations of the impulse signal based on the value of the edge signal v _i generated by the edge signal generating means. 3. The luminance signal enhancement processing apparatus according to claim 2, further comprising signal coefficient calculating means, wherein the larger the value of the impulse signal coefficient q _i , the larger the weighting coefficient a _i . 4. The weighting factor calculating means is the edge signal.
Edge signal v generated by the generation means_iBased on the value of
A small value that is small in the range you want to amplify as a small amplitude signal.
Amplitude signal coefficient r_iSmall amplitude signal coefficient calculation means for calculating
This small amplitude signal coefficient r _iThe smaller the value of
Coefficient a_iIs set to a large value.
Alternatively, the luminance signal enhancement processing device according to claim 3. 5. The weighting factor calculation means calculates a noise factor s _i indicating a minute amplitude signal which can be regarded as noise in a small amplitude signal based on the value of the edge signal v _i generated by the edge signal generation means. 5. The luminance signal enhancement processing device according to claim 3, further comprising a noise coefficient calculation means for calculating, wherein the smaller the value of the noise coefficient s _i , the smaller the weighting coefficient a _i .