KR100772404B1 - Pre-compensation methods and systems of high frequency component in a video scaler - Google Patents

Abstract

The present invention relates to a video scaling method and system in which high frequency components of an input video sequence are compensated prior to video scaling. The video scaling system includes a pre-compensator and a video scaler for the compensation of high frequency components of the input video sequence. The precompensator includes a high frequency component extractor, a noise detector, and a shoot suppressor. The high frequency component extractor extracts high frequency compensation components from the input video sequence. The noise detector adjusts the compensation gain to avoid the enhancement of the noise component. The shoot suppressor also adjusts the compensation gain to avoid shoot artifacts. The adjusted high frequency compensation video is added to the input video. The pre-compensated video sequence then passes through a video scaler to obtain scaled video. Thus, the sharpness of the scaled video is maintained or rather improved.

High Frequency Precompensated Video Scaling Scaler

Description

Pre-compensation methods and systems of high frequency component in a video scaler

1 shows a block diagram of a system illustrating a conventional scaling method.

2 shows an exemplary block diagram of a video scaling system according to an embodiment of the present invention for providing precompensation of high frequency image components on an input video signal.

FIG. 3 shows a block diagram of one embodiment of the video pre-compensator of FIG. 2 for compensation of high frequency components of an input video signal, in accordance with an embodiment of the present invention.

4 illustrates an example of high frequency peaking in pre-compensation of the input signal high frequency component, according to one embodiment of the invention.

5 shows an example of adjusting the high frequency component α (k) according to an embodiment of the present invention.

6 shows an example of adjusting signal p (k), in accordance with an embodiment of the present invention.

7 (a) to (d) show four examples of luminance patterns in which chute artifacts may occur at the boundary between a flat area and an increasing or decreasing area during precompensation of high frequency components. Shows.

8 illustrates an example of determining an intensity factor r (k) from a high frequency component α (k), according to an embodiment of the present invention.

9 illustrates an example of a parallel pre-compensation system for compensating for high frequency components prior to the video scaler of FIG. 2, in accordance with an embodiment of the present invention.

The present invention relates generally to video processing, and in particular to video scaling on video processing.

In TV systems, video scaling is often needed when the native resolution of the incoming video frame does not match the resolution of the display. Without loss of universality, the scaling ratio is assumed to be L / M and the greatest common divisor is gcd (L, M) = 1. As shown in FIG. 1, a conventional scaling system 100 is generally used to scale the input signal x (k) with a scaling ratio of any rational value. In such a system, the input signal x (k) is up-sampled by L of up-sampler 102, filtered by interpolation filter 104 of frequency response H _{L , M} , and then Is down-sampled by M of down-sampler 106. Such a process can be implemented using a polyphase structure. Using such a system, a two-dimensional video frame is first scaled in the horizontal direction at one scaling ratio and then scaled in the vertical direction at another scaling ratio, or first scaled in the vertical direction and then scaled in the horizontal direction.

In the video scaling system of FIG. 1, up-sampling extends the timescale with the factor L to obtain a new sequence u (k), with L-1 zero values between each sample of x (k). Insert it. In the frequency domain, up-sampling causes image components to appear at frequency 2π / L, 1 ≦ l ≦ L-1. Therefore, in order to prevent artifacts, the filter must be filtered by a low pass filter with a u (k) cutoff frequency of π / L. On the one hand, down-sampling takes every Mth sample of v (k) to obtain a scaled sequence y (k). However, such down-sampling mostly results in aliasing.

To prevent aliasing, the sequence v (k) must go through a low pass filter with a cutoff frequency [pi] / M prior to down-sampling. The cascade of two filters with cutoff frequencies of π / L and π / M consists of a single low pass interpolation filter H _{L , M} and cutoff frequencies min (π / L, π / M). Equivalent Therefore _, the frequency characteristics of the interpolation filters H _{L and M} depend on the L and M values.

Since the interpolation filters H _{L , M} are low pass filters, the scaled video lacks high frequency components, so the scaled video is often blurred and not as sharp as the original input video sequence.

Accordingly, it is an object of the present invention to provide a precompensation method and system for video scaling that overcomes the above disadvantages of the prior art. More particularly, it provides a video scaling method and system in which high frequency components of an input video sequence are compensated prior to video scaling. In this way the sharpness or detail of the scaled video is maintained or rather improved.

In one embodiment, the present invention provides a video scaling method and system in which high frequency components of an input video sequence are compensated prior to video scaling. One example of a video scaling system according to the present invention includes a pre-compensator and a video scaler for the compensation of high frequency components of an input video sequence.

The precompensator includes a high freq.component extractor, a noise detector, and a shoot suppressor. The high frequency component extractor extracts high frequency compensation components from the input video sequence. The noise detector adjusts the gain of compensation to avoid noise enhancement. The chute suppressor further adjusts the compensation gain to avoid chute artifacts. The high freq. Compensated video is added back to the input video. The pre-compensated video sequence then passes through a video scaler to obtain scaled video. Thus, the sharpness of the scaled video is maintained or rather improved.

2 shows a block diagram of one embodiment of a video scaling system 200 with precompensation of high frequency components of an input signal x (k), in accordance with an embodiment of the present invention. The system 200 includes a precompensator 202 and a video scaler 204 for compensating high frequency components of an input video sequence. The precompensator 202 first precompensates the high frequency components of the input signal x (k), and then the obtained signal x '(k) passes through the scaler 204 to obtain a scaled signal y (k). . Any scaler may be used instead of the scaler shown in FIG. In addition, the two one-dimensional scalers 204 can be cascaded to scale the two-dimensional video frame in the horizontal and vertical directions in any order to obtain a scaled video frame. To facilitate understanding of this description, the input signal x (k) can be thought of as a set of one-dimensional pixel values in the horizontal or vertical direction.

3 illustrates a block diagram of one embodiment of the video pre-compensator 202 shown in FIG. 2 for compensation of high frequency components of an input video signal, in accordance with an embodiment of the present invention. The precompensator 202 includes a high frequency component extractor 300, a chute suppressor 302, and a noise detector 304. The high frequency component extractor 300 extracts the high frequency compensation component d (k) from the input signal x (k). The chute suppressor 302 calculates a suppression factor g ₂ (k) to avoid chute artifacts. The noise detector 304 calculates a gain adjustment parameter g ₁ (k) based on the noise level.

In the precompensator 202, the precompensation gain g ₀ is multiplied by the gain adjustment parameter g ₁ (k) in the multiplier 306 to produce a product g ₀ g ₁ (k). The product g ₀ g ₁ (k) is further multiplied by the suppression factor g ₂ (k) in the multiplier 308 to produce the product g ₀ g ₁ (k) g ₂ (k). Then, the product g ₀ g ₁ (k) g ₂ (k) is multiplier 310 to generate the product g ₀ g ₁ g, g ₂ d k). Multiplied by the high frequency compensation component d (k). Then, the product g ₀ g ₁ (k) g ₂ (k) d (k) is added to the adder 312 to generate a precompensated signal x '(k) Is added to the input signal x (k).

x '(k) = x (k) + g ₀ · g ₁ (k) · g ₂ (k) · d (k).

이다. 만약 |α(k)|> t₃ 이라면 상기 신호 α(k)는 우회하여 과잉보상(overcompensation)을 피한다. 임계점 t₁,t₂,그리고 t₃ 은 0≤t₁≤t₂≤t₃ 을 만족하고, 임계점들은 수동으로 사전 설정되거나 동적으로 계산될 수 있다.In order to obtain the high frequency compensation component d (k), first the input signal x (k) passes through a high pass filter in the high frequency component extractor 300 to obtain a high frequency component α (k). For example, a high pass filter [-1,2, -1] can be used to extract α (k). Other high pass filters are also available. 4 shows an exemplary graph 400 for outputting the signal k by adjusting the high frequency component α (k) when t ₁ , t ₂ , t ₃ is the critical point. Basically, if 0 ≦ | α (k) | ≦ t ₁ , the amplitude of α (k) is reduced to avoid increasing noise, ie β (k) = α (k) * | α (k ) | / t ₁ If t ₁ <| α (k) | ≦ t ₂ , the signal α (k) is bypassed because the compensation will not be important in the narrow high frequency region. If t ₂ <| α (k) | ≦ t ₃ , the amplitude of α (k) is increased to have an important compensation, ie

to be. If | α (k) |> t _3, the signal α (k) is bypassed to avoid overcompensation. Threshold t _1, t _2, and t ₃ satisfy the 0≤t ₁ ≤t ₂ ≤t _3, and the critical point may be manually pre-set or calculated dynamically.

으로 계산되고,

는 상기 신호 x(k)의 로컬(local) 평균이다. 도 5는 P_max, R_min 그리고 R_max가 사전 설정된(pre-defined) 값들일 때, 신호 q(k)를 출력하기 위해 상기 신호 p(k)를 조정하는 예시 그래프(500)를 도시한다. 기본적으로 p(k)=0 일때, q(k)=R_min라 하자. 만약 p(k)≥ P_max 일때, q(k)= R_max 라 하자. 그리고, 만약 0<p(k)<P_max 이라면, q(k)는 선형적으로 보간된다. 임계점 t₁ ,t₂은 t₁= t₂=min(T, q(k)) 로 계산되고, 이때 T는 수동으로 설정될 수 있는 상수값이다. 임계점 t₃은 t₃=q(k) 으로 계산될 수 있다. An example of dynamically calculating the critical points t ₁ , t ₂ , t ₃ will now be described. Signal p (k)

Calculated as

Is the local average of the signal x (k). FIG. 5 shows an example graph 500 for adjusting the signal p (k) to output signal q (k) when P _max , R _min and R _max are pre-defined values. Basically, when p (k) = 0, let q (k) = R _min . If p (k) ≥ P _max , then q (k) = R _max . And if 0 <p (k) <P _max , q (k) is linearly interpolated. Threshold t ₁ , t ₂ is calculated as t ₁ = t ₂ = min (T, q (k)), where T is a constant value that can be set manually. Threshold t ₃ can be calculated as t ₃ = q (k).

Once the signal β (k) is obtained, the high frequency compensation component d (k) is calculated as d (k) = β (k) −α (k).

Referring back to FIG. 3, noise detector 304 is used to scale down high frequency compensation, which appears to have a small local standard deviation (or variance). Small local standard deviations indicate relatively flat areas. If you do not reduce the compensation in such areas, the noise will increase.

In a two-dimensional video frame, the local standard deviation σ (k) is often calculated based on a rectangular neighboring window where the current pixel is centered. Other methods can also be used to calculate local standard deviations. The gain adjustment parameter g ₁ (k) is a monotonically increasing function of the local standard deviation. 6 shows an example of the monotonically increasing function 600, where σ (k) is less than the threshold τ ₁ , the input signal x (k) is in a flat region and the adjustment parameter is g ₁ (k) = 0. Is set. If σ (k) is greater than the threshold τ ₂ (τ ₂ ≥τ ₁ ), the input signal x (k) contains useful edge information and the adjustment parameter is g ₁ (k) to fully compensate for the high frequency components. ) = 1. If τ ₁ ≦ σ (k) ≦ τ ₂ , the adjustment parameter g ₁ (k) is linearly interpolated in a soft-switching manner as illustrated in FIG. 6. In particular, if we consider linear soft switching as an example, then when τ ₁ ≤σ (k) ≤τ ₂ , then g ₁ (k) = (σ (k)-τ ₁ )) / (τ ₂ -τ ₁ ) have. Thresholds τ ₁ and τ ₂ may be set to constant values or dynamically adjusted based on noise estimates. When the noise estimate is high and the video sequence is considered noisy, τ ₁ and τ _{2 should} also be set to relatively large values. When the noise estimate is low and the video sequence is considered to be clean, τ ₁ and τ ₂ are set to relatively small values and fine details of the video frame are better precompensated. Can be. The relation between the noise detection threshold τ ₁ , τ ₂ and the noise estimate σ _e can be expressed as Equation 2 below.

τ ₁ = c ₁ * σ _e ,

τ ₂ = c ₂ * σ _e ,

At this time, c ₁ and c ₂ are preset values satisfying c ₂ ≥ c ₁ ≥ 0. The noise estimate σ _e is incorporated herein by reference and described in commonly assigned US patent application Ser. No. 10 / 991,265 "Methods to estimate noise variance from a video sequence". Obtained by the method. According to this, if there is no movement or small movement between two consecutive frames, the image structure can be eliminated by calculating local differences, thus a strong tolerant estimate is obtained. Using the mean absolute error (MAE) as the local difference, we can compute α as α ≒ E (hat y) = 2 * σ ₀ / √π when α is the first predictive estimate of hat y. . The noise estimate σ _e is then calculated as σ _e = α / 2 * √π. The inventors further note that precompensation in the horizontal and vertical directions can share the same noise detector to reduce computational cost.

In precompensation of high frequency components, chute artifacts usually occur in the edge region. In particular, chute artifacts usually occur near the point of sharp turning of pixel luminance that varies from a relatively smooth region. 7 (a)-(d) show four example luminance patterns 702, 704, 706, and 708, in which chute artifacts occur during the precompensation of high frequency components, respectively. In each pattern, eight pixels 700 (●) are shown for depicting purposes. The number of pixels 700 actually associated may vary depending on the number of filter taps of the high pass filter in the high frequency component extractor 300 of FIG. 3. Common points can be found in the four patterns, in which Figs. 7 (a) to 7 (d) all include a varying area and a wide flat area in terms of pixel luminance level.

Based on the above analysis, the chute suppressor 302 of FIG. 3 further performs a symmetry test and an intensity test. For symmetry check, the chute suppressor 302 checks the luminance variance of the pixels in both directions of the current pixel within the filtering range. Based on the inspection result, different patterns of luminance variance in the neighborhood of the current pixel are classified. Thus, higher suppression is made for those patterns where overshoot / undershoot is more likely to occur. For the intensity test, the chute suppressor 302 checks the magnitude of the high frequency component α (k). If the value is small, it is unlikely that obvious chute artifacts will appear at that point. Thus, suppression is associated with the intensity of α (k) at each pixel point.

The purpose of the symmetry test is to detect the patterns shown in Figs. 7 (a) to (d). Within the filtering range, if the pixel luminance curve is close to any pattern in Figs. 7 (a) to (d), then precompensation should be suppressed at that point. Let N be a case where (2 * N + 1) becomes the length of the high pass filter in the high frequency component extractor 300. In order to check the symmetry of the pixel luminance curve with reference to the position of x (k) and calculate the symmetry factor s (k), the values M1 and M2 are first calculated as shown in Equations 3 and 4 below. .

M _l = max (d _{0 , -N} , d _{0 , -N + 1} ,…, d _{0 , -1} )

M _r = max (d _{N , 0} , d _{N -1,0} ,…, d _{1 , 0} )

d _{i , j} is d _{i , j} = | x (k + i) minus the absolute difference between x (k + i) and x (k + j), as in x (k + j) |.

The M _l value is the maximum absolute difference between x (k) and any pixel to its left in the filtering range. Similarly, the M _r value is the maximum absolute difference between x (k) and any pixel in its right direction within the filtering range. If M _l and M _r are zero, x (k) is in the flat region. In this case, the symmetry factor s (k) is set to 1 indicating no suppression is needed. This is because the high frequency component d (k) becomes zero. If only one of M _l and M _r is zero, the pixel luminance pattern is close to any of those shown in Figs. 7 (a) to (d). Therefore, it is very likely that chute artifacts will appear at such a point. In this case, the symmetry factor s (k) is set to zero to completely suppress the precompensation gain. If neither M _l nor M _r is zero, two values, A _l and A _r , are calculated as shown in Equation 5 below.

Where A _l is the average of the absolute differences in the left direction of x (k) and A _r is the average of the absolute differences in the right direction of x (k). Then the symmetry factor s (k) is calculated as shown in Equation 6 below.

Similarly, more restrictive conditions are used to calculate the symmetry factor s (k) as shown in Equation 7 below.

In Equation 7, m _l is the minimum value of the absolute differences on the left side of x (k), and m _r is the minimum value of the absolute differences in the right direction of x (k), as shown in Equation 8 below.

In the intensity test, the intensity factor r (k) is calculated as a monotonically increasing function of the absolute value of the high frequency component α (k). 8 shows an example of the monotonically increasing function 800 where r (k) is zero if | α (k) | is less than the threshold ζ ₁ . If | α (k) | is greater than the critical point ζ ₂ , r (k) is one. When ζ ₁ ≤ | α (k) | ≤ζ ₂ , r (k) is linearly interpolated by a soft switching method. Threshold ζ ₁ and ζ ₂ are pre-defined values to satisfy the 0≤ζ ₁ ≤ζ _2.

When the symmetry factor s (k) and the intensity factor r (k) are obtained, the suppression factor g ₂ (k) is calculated as in Equation 9 below.

When r (k) = 1, the high frequency component α (k) becomes strong and g ₂ (k) = s (k). Thus, chute suppression is done only based on the symmetry factor s (k). When r (k) = 0, the high pass filter output α (k) is considered very weak and the suppression factor g ₂ (k) has a value of 1 meaning no suppression is applied.

Precompensation of the high frequency components in the video frame may be implemented with a precompensation history structure 900 as shown in FIG. 9. Where x (i, j) points to an input two-dimensional video frame signal, x '(i, j) points to a pre-compensated video frame signal, and (i, j) points to a geometric position. The system 900 includes a high frequency component extractor 904 for the horizontal direction, a chute suppressor 904 for the horizontal direction, a high frequency component extractor 906 for the vertical direction, a chute suppressor 908 for the vertical direction, And a noise detector 910.

First, the system 900 extracts the high frequency components in the horizontal direction (using the extractor 902) and extracts in the vertical direction (using the extractor 906). The gain of each component (i.e., horizontal and vertical high frequency components) is then adjusted in the horizontal direction (using suppressor 904) or in the vertical direction (using suppressor 908) by the corresponding suppressor. In particular, in the horizontal direction, the suppression factor g _2h (k) output from the suppressor 904 is multiplied by the gain g _h , and again the product (g _h * g _2h (k)) is obtained by the extractor 902. It is multiplied by the compensation component d _h (k) output from to produce a product (g _h * d _h (k) * g _2h (k)).

In the vertical direction, the suppression factor g _2v (k) output from the suppressor 908 is multiplied by the gain g _v, and again the product g _v * g _2v (k) is the compensation component from the extractor 906. multiplied by d _v (k) The product (g _h * d _h (k) * g _2h (k)) and (g _v * d _v (k) * g _2v (k)) are added together again by the gain adjustment parameter from the noise detector 910. Adjusted to obtain a compensation component [g ₁ (k) * ((g _h * d _h (k) * g _2h (k)) + (g _v * d _v (k) * g _2v (k)))]. Then, the obtained compensation component is added with the original video frame x (i, j) to obtain a precompensated video frame x '(i, j) as shown in Equation 10 below.

The compensated video frame x '(i, j) is input to a traditional video scaler or some other video scaler to obtain scaled video as shown in FIG.

Although the present invention has described many details with reference to preferred versions, other versions are possible. Accordingly, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

The lack of high-frequency components of conventional scaled video is often lacking and often blurred and not as sharp as the original input video sequence, so sharpness or detail of the scaled video is maintained or rather improved. It is effective.

Claims (40)

In the video scaling method, And precompensating the high frequency components of the input video signal prior to video scaling. The method of claim 1, The precompensation step includes extracting a high frequency compensation component from the input signal by performing a high frequency component extraction. The method of claim 2, Wherein said precompensation step includes determining a chute suppression factor to adjust the gain of said compensation to avoid chute artifacts. The method of claim 3, And said precompensation step includes determining a gain adjustment factor for adjusting the gain of said compensation to avoid amplification of noise components. The method of claim 4, wherein And the precompensation step includes applying the chute suppression factor and the gain adjustment factor to the high frequency compensation component to generate a compensation factor. The method of claim 5, Combining the compensation factor with the input signal to produce a pre-compensated signal. The method of claim 6, Scaling the pre-compensated signal to obtain a scaled signal, thereby maintaining the clarity of the scaled signal. The method of claim 2, Extracting the high frequency component by extracting the high frequency component from the input signal, Passing the input signal through a high pass filter to obtain a high frequency component α (k); And Determining the high frequency compensation component as a function of the high frequency component α (k). The method of claim 8, Determining the high frequency compensation component as a function of the high frequency component α (k), When the critical point t _1, t _2, and t ₃ satisfy the 0≤t ₁ ≤t ₂ ≤t _3, If 0≤ | α (k) | If ≤ t ₁ , the amplitude of α (k) is reduced to avoid amplification of noise; If t ₁ <| α (k) | If ≤ t ₂ , α (k) is bypassed; If t ₂ <| α (k) | ≤ t ₃ , α (k) increases; If | α (k) | > t ₃ , α (k) further comprises adjusting a high frequency component that bypasses and avoids overcompensation. The method of claim 9, Reducing the amplitude of α (k) multiplies α (k) by the adjustment factor to produce a signal β (k) with β (k) = α (k) * | α (k) | / t ₁ . And a video scaling method. The method of claim 9, The determining of the high frequency compensation component d (k) further includes determining d (k) = β (k) −α (k) when β (k) is a function of α (k). Video scaling method. The method of claim 9, Increasing the amplitude of α (k) by applying an adjustment factor

Generating a signal β (k). The method of claim 12, The determining of the high frequency compensation component d (k) further includes determining d (k) = β (k) −α (k) when β (k) is a function of α (k). Video scaling method. The method of claim 4, wherein And the gain adjustment factor is a monotonically increasing function of the local standard deviation. The method of claim 8, And based on the high frequency component α (k), determining a chute suppression factor for adjusting the gain of the compensation to perform chute suppression to avoid chute artifacts. The method of claim 15, Performing the chute suppression, Performing a symmetry check by checking the luminance distribution of the pixels in both directions of the current pixel within the filtering range; Based on the inspection results, further comprising performing higher suppression on patterns where overshoot / undershoot is more likely to occur. The method of claim 15, Performing the chute suppression, Performing an intensity test by checking the magnitude of the high frequency component α (k); And And performing suppression at each input signal pixel position as a function of intensity of α (k). The method of claim 1, The input signal is, Said precompensation of said high frequency component of said input signal comprises a two dimensional array of pixels performed in a horizontal direction to determine a horizontal compensation factor and determined in a vertical direction to determine a vertical compensation factor. . The method of claim 18, Combining horizontal and vertical compensation factors with the input signal to produce a precompensated signal. A video scaling system for scaling an input video signal, And a precompensator to precompensate the high frequency components of the input signal to produce a precompensated signal prior to video scaling. The method of claim 20, And said precompensator comprises an extractor for performing high frequency component extraction to extract high frequency compensation components from said input signal. The method of claim 21, And the precompensator further comprises a chute suppressor that determines a chute suppression factor for adjusting the gain of the compensation to avoid chute artifacts. The method of claim 22, And the precompensator further comprises a noise detector that determines a gain adjustment factor for adjusting the gain of the compensation to avoid enhancement of the noise component. The method of claim 23, wherein And the precompensator generates a compensation factor by applying the chute suppression factor and the gain adjustment factor to the high frequency compensation. The method of claim 24, The precompensator combines the compensation factor with the input signal to produce a precompensated signal. The method of claim 25, And a scaler for scaling the pre-compensated signal to obtain a scaled signal, thereby maintaining the sharpness of the scaled signal. The method of claim 21, The extractor extracts a high frequency component by extracting a high frequency component by passing the input signal through a high pass filter to obtain a high frequency component α (k); And The precompensator is a precompensator for determining the high frequency compensation component as a function of the high frequency component α (k). The method of claim 27, The precompensator determines the high frequency compensation component as a function of the high frequency component α (k), When the critical point t _1, t _2, and t ₃ satisfy the 0≤t ₁ ≤t ₂ ≤t _3, If 0≤ | α (k) | If ≤ t ₁ , the amplitude of α (k) is reduced to avoid amplification of noise; If t ₁ <| α (k) | If ≤ t ₂ , α (k) is bypassed; If t ₂ <| α (k) | ≤ t ₃ , α (k) increases; If | α (k) | > t ₃ , α (k) adjusts high frequency components to bypass and avoid overcompensation. The method of claim 28, The precompensator reduces the amplitude of α (k) by multiplying α (k) by the adjustment factor to produce a signal β (k) with β (k) = α (k) * | α (k) | / t ₁ . And a video scaling system. The method of claim 28, The precompensator determines the high frequency compensation component d (k) by determining d (k) = β (k) −α (k) when β (k) is a function of α (k). system. The method of claim 28, The precompensator increases the amplitude of α (k) by applying an adjustment factor to α (k)

And a signal β (k). The method of claim 31, wherein The precompensator determines the high frequency compensation component d (k) by determining d (k) = β (k) −α (k) when β (k) is a function of α (k) Scaling system. The method of claim 23, wherein The gain adjustment factor is a monotonically increasing function of the local standard deviation. The method of claim 27, And a chute suppressor for avoiding chute artifacts by determining a chute suppression factor for adjusting the gain of the compensation based on the high frequency component a (k). The method of claim 34, wherein The chute suppressor, Perform a symmetry check by checking the luminance variance of the pixels in both directions of the current pixel within the filtering range; Based on the inspection results, shoot suppression is performed by making higher suppression for patterns where overshoot / undershoot is more likely to occur. The method of claim 34, wherein The chute suppressor, An intensity test is performed by checking the magnitude of the high frequency component α (k), Suit suppression is performed by suppressing at each input signal pixel position as a function of intensity of α (k). The method of claim 20, The input signal is, Said precompensation of said high frequency component of said input signal comprises a two dimensional array of pixels performed in a horizontal direction to determine a horizontal compensation factor and in a vertical direction to determine a vertical compensation factor. . The method of claim 37, The precompensator combines the horizontal and vertical compensation factors with the input signal to produce the precompensated signal. The method of claim 20, And the pre-compensator performs cascade pre-compensation. The method of claim 20, And the pre-compensator performs parallel pre-compensation.

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