JP4785953B2 - Video signal preprocessing method, video signal preprocessing apparatus, and video signal preprocessing program - Google Patents

Description

  The present invention relates to a video signal preprocessing method for processing a video signal prior to encoding for the purpose of improving video quality in high-efficiency video encoding, particularly in low bit rate encoding.

  The video signal is represented by three primary colors of R (red), G (green), and B (blue) in the display, but in normal high-efficiency encoding, RGB (linearly converted) Y (luminance), It is usually expressed by three signals of U (blue-yellow difference) and V (red-green difference).

As a conventional video pre-processing method for the purpose of improving the coding efficiency, paying particular attention to the spatial undulations of U and V signals that are less perceptible than Y signals,
(I) A so-called 4: 2: 2 signal (RGB specific capacity 1/2) thinned by 1/2 in the horizontal direction of U and V,
(Ii) U, so-called 4 thinned out to 1/2 V respectively horizontal and vertical in each direction: 2: 0 signal (RGB ratio volume 2/3),
(iii) U, the so-called thinned to 1/4 V respectively horizontally 4: 1: 1 signal (RGB ratio volume 2/3),
It is widely done to reduce the amount of information actively.

  Further, the following patent / non-patent documents describe the following properties as technologies relating to preprocessing of video signals.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique in which the preprocessing is limited to a spatial low-pass filter (LPF), and the LPF intensity is adaptively changed according to luminance change or edge presence / absence.

  Patent Document 2 below shows that preprocessing is performed by spatial LPF and signal level correction, image size change, noise reduction, and the like.

  Japanese Patent Application Laid-Open No. H10-228688 discloses that spatial LPF or noise removal is performed as preprocessing.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for adaptively changing the LPF intensity by using a “spatio-temporal filter” in the meaning of a spatial LPF that is adapted to scene changes.

  Non-Patent Document 1 below shows what reduces a noise component included in a video signal.

  Non-Patent Document 2 below shows what performs temporal preprocessing for the purpose of code amount reduction.

  Non-Patent Document 3 below describes a technique for flattening high-frequency portions such as turf in an image while leaving an edge.

  Each of these techniques adaptively changes the degree of preprocessing or removes noise, and can be applied to the high frequency band of a video signal, or the noise band or high frequency of a space time. This is a technology aimed at reducing video information.

  By applying such pre-processing to the video signal, a part of the band of the signal is reduced, and a favorable effect is obtained that the code amount (bit rate) is reduced as a result of the subsequent encoding.

  However, conventionally, there has been no video signal pre-processing method that effectively reduces the amount of information by focusing on a part of the spatio-temporal band of the luminance and color difference signals (low and medium frequency regions, etc.).

JP 2005-026747 A JP 2003-250156 A JP 2002-016910 A JP 2001-251629 A

Matsumura, Haseyama, Kitajima: “Kalman Filter by Adaptive Image Modeling for Effective Noise Reduction”, IEICE Transactions, Vol.J86-D2, No.2, pp.212-222, Feb .2003 Tsuji, Sakaya, Yashima, Kobayashi: “Study of pre-filter for low bit rate coding based on anisotropic diffusion”, Image coding symposium PCSJ2001, P-5.19, Nov.2001 Kizen, Yashima, Kobayashi: "A study on edge-preserving prefilter control method for low bit rate video coding", Image coding symposium PCSJ2000, P-P1.14, Nov.2000

  In view of the above-described problems, the present invention performs preprocessing of luminance / color difference signals that are difficult to perceive according to human perceptual characteristics, and reduces the amount of information before encoding. The purpose is to reduce the amount of code as a result of subsequent encoding while preserving the perceptual impression as much as possible.

  Signals that do not affect the perception as much as possible when the signal of luminance and color difference is subjected to signal processing with a digital filter and displayed as a video, quantitatively assessing how this processing will affect human perception Select a process.

[Human visual and perceptual characteristics]
As a result of the psychophysical experiment conducted by the present inventor, it was found that the movement perceived by the human eye and brain has the following properties.

  Perceptual characteristics 1: It is difficult to perceive video signal fluctuations (undulations and movements) such that the luminance is constant and only the blue-yellow direction in the color difference space changes temporally or spatially.

  Perceptual characteristics 2: Almost the same appearance is perceived depending on whether or not a spatial or temporal BEF (Band Elimination Filter) is applied to luminance / color differences.

  Perceptual characteristic 3: Motion is difficult to perceive when temporal high pass filter (High Pass Filter) is applied to a video signal with only a luminance signal, but even if temporal HPF is applied only to the luminance signal of a luminance color difference signal, the motion is Perceptible (however, only the DC component remains).

  Here, BEF is a band suppression filter, and HPF is a high-pass filter.

[First related invention]
The video signal pre-processing method according to the related invention is a method for applying temporal one-dimensional LPF to the U component (corresponding to the blue-yellow direction of the color difference space) of the YUV-converted video signal in view of the perceptual characteristic 1. It is.

  From subjective experiments, it has been found that even if the time resolution of the blue-yellow signal is reduced to about 2 Hz, no extreme deterioration is felt.

  The order and filter coefficients of the LPF are arbitrary, and for example, a [1/4, 1/2, 1/4] 3-tap filter can be mentioned. This filter is applied at the same spatial position in adjacent frames.

That is, when the spatial position is (x, y) and the U signal at time (frame number) t is U (x, y, t), a new U signal U ′ (x, y, t) is
U '(x, y, t) = (1/4) U (x, y, t-1) + (1/2) U (x, y, t) + (1/4) U (x, y , t + 1)
Seek like.

  For example, the portion exceeding the end in time is treated as if the end image signal is repeated.

[Invention]
In the video signal preprocessing method according to the present invention, in consideration of the perceptual characteristic 1, a spatial two-dimensional LPF is applied to the U component of the YUV converted video signal.

  From the subjective experiment, it is known that the spatial resolution of the blue-yellow signal does not feel extreme deterioration even if it is reduced to about 3 cycles / image.

LPF order and filter coefficients are arbitrary, but for example, [1/4, 1/2, 1/4] 3-tap filters are applied vertically and horizontally.
1/16 1/8 1/16
1/8 1/4 1/8
1/16 1/8 1/16
Is mentioned. This filter is applied in the adjacent space position of the same frame.

That is, a new U signal U ′ (x, y, t)
U '(x, y, t) = (1/16) U (x-1, y-1, t) + (1/8) U (x, y-1, t) + (1/16) U (x + 1, y-1, t) +
(1/8) U (x-1, y, t) + (1/4) U (x, y, t) + (1/8) U (x + 1, y, t) +
(1/16) U (x-1, y + 1, t) + (1/8) U (x, y + 1, t) + (1/16) U (x + 1, y + 1, t )
Seek like.

  For the portion beyond the screen edge, for example, the edge image signal is treated as being repeated.

[Second related invention]
The video signal pre-processing method according to this related invention is to apply temporal one-dimensional BEF to each of Y, U, and V components of a YUV converted video signal in view of the perceptual characteristic 2.

  From the subjective experiment, it is known that even when the low frequency cutoff frequency of the time BEF is about 2 Hz and the high frequency cutoff frequency is about 6 Hz, no extreme deterioration is felt. In a normal image signal, approximately half of the power is in this band, so a great reduction in information can be expected.

  The order and filter coefficients of BEF are arbitrary, but for example, a 5-tap filter of [0.3, 0, 0.4, 0, 0.3] can be mentioned. This filter is applied at the same spatial position in adjacent frames.

That is, when the Y signal at the spatial position (x, y) and time t is Y (x, y, t), the new Y signal Y ′ (x, y, t) is
Y ′ (x, y, t) = 0.3 Y (x, y, t−2) +0.4 Y (x, y, t) +0.3 Y (x, y, t + 2)
Seek like.

  For example, the portion exceeding the end in time is treated as if the end image signal is repeated.

[Third related invention]
The video signal pre-processing method according to this related invention is to apply spatial two-dimensional BEF to each of Y, U and V components of a YUV converted video signal in view of the perceptual characteristic 2.

  From the subjective experiment, it is known that even if the low-frequency cutoff frequency of the spatial BEF is about 3 cycles / image and the high-frequency cutoff frequency is about 8 cycles / image, no extreme deterioration is felt.

The order and filter coefficients of BEF are arbitrary. For example, a 5-tap filter of [0.3, 0, 0.4, 0, 0.3] is applied vertically and horizontally.
O.09 0 0.12 0 0.09
0 0 0 0 0
O.12 0 0.16 0 0.12
0 0 0 0 0
O.09 0 0.12 0 0.09
Is mentioned. This filter is applied in the adjacent space position of the same frame.

That is, a new Y signal Y ′ (x, y, t)
Y '(x, y, t) = 0.09Y (x-2, y-2, t) + 0.12Y (x, y-2, t) + 0.09Y (x + 2, y-2, t) +
0.12Y (x-2, y, t) + 0.16Y (x, y, t) + 0.12Y (x + 2, y, t) +
0.09Y (x-2, y + 2, t) + 0.12Y (x, y + 2, t) + 0.09Y (x + 2, y + 2, t)
Seek like.

  For the portion beyond the screen edge, for example, the edge image signal is treated as being repeated.

[Fourth related invention]
In the video signal preprocessing method according to this related invention, in consideration of the perceptual characteristic 3, a temporal HPF (however, direct current is stored) is applied to the Y component of the YUV converted video signal.

  From subjective experiments, it has been found that even if the cutoff frequency of temporal HPF for the Y component is about 5 Hz, no extreme deterioration is felt.

  Although the filter coefficient of HPF is arbitrary, for example, a 3-tap filter of [−1/2, 1, −1/2] is applied.

  This filter is applied at the same spatial position in adjacent frames.

That is, a new Y signal Y ′ (x, y, t)
Y ′ (x, y, t) = − (1/2) Y (x, y, t−1) + Y (x, y, t) − (1/2) Y (x, y, t + 1)
Seek like.

  Next, a direct current component is added at each pixel position (x, y) as follows.

Y '(x, y, t ) = Y' (x, y, t) + Σ t Y (x, y, t) / N
The second term corresponds to the direct current DC. N is the number of frames.

[Fifth related invention]
The video signal preprocessing method according to the related invention attenuates a partial band of a luminance / chrominance-separated video signal by combining any of the present invention and the video signal preprocessing methods according to the first to fourth related inventions. Let Which video signal pre-processing method is applied in combination may be fixedly determined in advance, or a method of allowing the user to select each time may be used.

  The digital operation of the filter as described above can be realized by a computer and an image processing program, and the program can be provided by being recorded on a computer-readable recording medium or provided through a network. It is.

  As described above, the present invention focuses on a band different from a high frequency band called a color difference selective LPF, which is a conventional scheme based on spatial and temporal LPF, and reduces the band. Considering that the power of the normal video signal is biased to a low frequency in both time and space, the power reduced by the present invention can be expected to be equal to or higher than that of the conventional system.

  By applying the pre-processing as in the present invention to the video signal, it is possible to reduce the bandwidth that cannot be reduced by the conventional method but must remain, and as a result, the encoding efficiency of the subsequent stage can be improved compared to the conventional method. A special effect is born.

It is a figure which shows the structural example of the video signal pre-processing apparatus which concerns on this invention. It is a process flowchart of a 1st signal processing program. It is a processing flowchart of the 2nd signal processing program. It is a conceptual diagram of the filter used in the Example of this invention. It is a figure which shows the example of the increase / decrease method of contrast. It is a figure which shows the sharpening phenomenon of the motion in the image | video which performed the time filter. It is a figure which shows the sharpening phenomenon of the motion in the image | video which gave the spatial filter. It is a figure which shows the relationship of each correct answer rate of the image | video A, the image | video B, and the synthetic | combination image | video A & B. It is a figure which shows the comparison of the correct answer rate of synthetic | combination image | video A & B, and the estimated correct answer rate from each of the image | video A and the image | video B.

  FIG. 1 is a diagram showing a configuration example of a video signal preprocessing apparatus according to the present invention.

  This video signal pre-processing apparatus has a luminance / chrominance-separated video signal input means 1, a CPU 2 for executing a program, a memory (RAM) 3, a digital filter unit 4 for performing filter processing, and a band attenuation by pre-processing. The output means 5 for outputting the luminance / chrominance-separated video signal obtained as a result of the processing, the filter information storage unit 6 for storing the filter information, and the program storage unit 7 for storing the program for processing the signal are connected to each other. And a bus line 8.

  The filter information storage unit 6 stores filter coefficients (parameters) for each type of digital filter set in advance. The program storage unit 7 includes signal processing programs 11a, 11b, 11c,... For executing signal preprocessing corresponding to the type of digital filter to be applied, and a signal processing control program 10 for performing activation control thereof. And are stored. When there is only one signal processing program, the signal processing control program 10 may not be used.

  The CPU 2 executes the signal processing control program 10 loaded from the program storage unit 7, reads out a signal processing program selected in advance or a signal processing program designated by the user from the program storage unit 7 and executes it. The CPU 2 loads a filter coefficient from the filter information storage unit 6 by executing a signal processing program, repeats processing for a part of the video signal, and performs processing for all input signals.

  The RAM 3 temporarily stores output data, and the digital filter unit 4 executes one-dimensional filter processing or two-dimensional filter processing on the signal series on the memory in accordance with the filter coefficient and the instruction from the CPU 2. Generate the necessary video data.

  The storage device in the present video signal preprocessing device is provided with a filter information storage unit 6 and a program storage unit 7, but the filter information and the signal processing program stored therein can be changed separately. . For example, the signal processing program 11a is a program for realizing the first related invention described above, and the signal processing program 11b is a program for realizing the present invention. Similarly, the other signal processing program 11c and the like are programs for applying a specific digital filter process to the input signal and attenuating a part of the band.

  FIG. 2 is a processing flowchart of the signal processing program 11a. The video signal preprocessing operation for realizing the first related invention will be described below with reference to FIG.

  When an instruction to start processing is issued, in step S11, a luminance color difference separation type video signal is input using the input means 1 in accordance with the signal processing program 11a. Next, in step S12, the LPF filter coefficient for attenuating the time band is loaded from the filter information storage unit 6.

  In step S13, one unprocessed spatial position (x, y) is determined. Subsequently, in step S14, the luminance signal sequence and red-green difference signal sequence (both one-dimensional columns) for the entire time at the determined spatial position (x, y) are extracted and temporarily stored using a memory. . In step S15, a blue-yellow difference signal sequence for all time at the spatial position (x, y) is similarly extracted.

  Next, in step S16, the LPF filter coefficient and the digital filter unit 4 are used to perform filter processing (one-dimensional processing) on the signal series. In step S17, the processed signal sequence generated by the filter process is temporarily stored using a memory.

  Thereafter, in step S18, it is determined whether all the spatial positions (x, y) have been processed. If there is an unprocessed spatial position (x, y), the process returns to step S13. When all the spatial positions (x, y) have been processed, the process proceeds to step S19, where the information stored in the memory is output using the output means 5 in the form of the same luminance / chrominance separation type video signal as the input, and the process ends. .

  FIG. 3 is a processing flowchart of the signal processing program 11b. The video signal preprocessing operation for realizing the present invention will be described below with reference to FIG.

  When an instruction to start processing is issued, in step S21, a luminance color difference separation type video signal is input using the input means 1 in accordance with the signal processing program 11b. Next, in step S22, LPF filter coefficients for attenuating the spatial band are loaded from the filter information storage unit 6.

  In step S23, one unprocessed time t (frame number) is determined. Subsequently, in step S24, the luminance signals and red-green difference frames (both two-dimensional) of all frames at the determined time t are extracted and temporarily stored using a memory. In step S25, similarly, a blue-yellow difference signal frame at time t is extracted.

  Next, in step S26, the frame is subjected to filter processing (two-dimensional processing) using the LPF filter coefficient and the digital filter unit 4. In step S27, the generated processed frame is temporarily stored using a memory.

  Thereafter, in step S28, it is determined whether all the times t have been processed. If there is an unprocessed frame at time t, the process returns to step S23. When all the processes at time t have been completed, the process proceeds to step S29, where the information stored in the memory is output using the output means 5 in the form of the same luminance / chrominance separation type video signal as input, and the process ends.

  Although the first related invention and the embodiment of the video signal preprocessing according to the present invention have been described above, the video signal preprocessing according to the second, third, and fourth related inventions is similarly determined in advance. It can be executed by the CPU 2 using the filter coefficient and the corresponding signal processing program.

  When realizing the video signal preprocessing according to the fifth related invention, the video signal preprocessing according to the fifth related invention may be realized by using a dedicated signal processing program for causing the CPU 2 to execute the video signal preprocessing. , By executing the signal processing control program 10, several programs are selected from the signal processing programs 11 a, 11 b, 11 c,. It can also be realized by executing sequentially.

  FIG. 4 shows a conceptual diagram of a filter used in an embodiment of the present invention and related invention. FIG. 4A shows an example of a low-pass filter (LPF), which cuts the high frequency band and leaves the low frequency band. FIG. 4B is an example of a high-pass filter (HPF), which cuts the low frequency band and leaves the high frequency band. FIG. 4C shows an example of a band suppression filter (BEF), which is the sum of LPF and HPF in this embodiment.

  The results of experiments conducted to confirm the effects of the present invention and related inventions are shown below. The effect of the temporal and spatial filters on motion sharpening was measured as follows.

  • The subject increases the apparent contrast of the image and identifies the contrast that appears to be equivalent to the filtered image.

  ・ Contrast operation is performed by relatively increasing or decreasing the amplitude of the high spatial frequency component. FIG. 5 shows an example of a method for increasing / decreasing contrast.

[Experiment 1]
FIG. 6 shows the motion sharpening phenomenon in the image subjected to the time filter. The experiment was performed with the number of images = 12, and the number of subjects = 14. From this experiment, the following findings were obtained. As shown in FIG. 6, it was found that sharpening occurs in the temporal low frequency component (temporal LPF). In addition, although an image having only temporal high-frequency components (temporal HPF) is blurred, it has been confirmed that strong sharpening occurs in temporal BEF images due to the interaction between the two. In this experiment, the temporal LPF cutoff frequency is 2 Hz, and the temporal HPF cutoff frequency is 6 Hz (the temporal BEF low-frequency cutoff frequency and high-frequency cutoff frequency are 2 Hz and 6 Hz, respectively).

[Experiment 2]
FIG. 7 shows the motion sharpening phenomenon in the image subjected to the spatial filter. The experiment was performed with the number of images = 12, and the number of subjects = 14. From this experiment, the following findings were obtained. As shown in FIG. 7, the low spatial frequency component (spatial LPF) causes sharpening. In addition, although an image having only a high spatial frequency component (spatial HPF) is blurred, it can be confirmed that, in a spatial BEF image obtained by adding low spatial frequency components, the amount of sharpening increases due to the interaction between the two. It was. In this experiment, the spatial LPF cutoff frequency is 3 cycles / image, and the spatial HPF cutoff frequency is 8 cycles / image (the spatial BEF low-frequency cutoff frequency and high-frequency cutoff frequency are 3 cycles / image, respectively.・ 8cycles / image).

[Experiment 3]
The following images were prepared to examine visual stimuli.
• Image A: Image obtained by filtering the luminance signal with temporal HPF (cutoff frequency = 5 Hz, but leaving a DC component) • Image B: Image with only color difference (no filtering)
・ Video A & B: Composite video of video A and video B To subject, these video A, video B, and composite video A & B are sent in a short time (0.5 second to 4.0 seconds) by “forward” or “reverse”. The experiment of presenting and assigning either the order or the reverse was performed with the number of images = 12 and the number of subjects = 5.

  The results of these experiments are shown in FIGS. FIG. 8 shows the relationship between the correct answer rates of video A, video B, and composite video A & B.

FIG. 9 shows a comparison between the correct answer rate of the composite video A & B and the estimated correct answer rate from each of the video A and the video B. In FIG. 9, the calculation of probability weighting from each of video A and video B was performed based on the following references.
[References] SMWuerger et al .: "The integration of auditory and visual motion signals at threshold", Perception & Psychophysics, Vol.65, No.8, pp.1188-1196, 2003.
The following findings were obtained from these experimental results.
The determination of the moving direction of image A with temporal HPF applied to the luminance component is improved by adding color component image B (see FIG. 8).
-The correct answer rate of the composite video A & B exceeded the probability weighting of the correct answer rate of the individual components of the video A and the video B (see FIG. 9).

  This experimental result shows that even when temporal HPF is applied to the luminance signal as in the preprocessing according to the fourth related invention, the presence of the color difference signal helps to perceive motion.

  As described above, in the prior art, as a pre-processing for image coding, only the reduction of the high frequency band / time band was considered, whereas in the present invention, the spatial band / time band / color is considered. Based on the results of experiments on human visual and perceptual characteristics that human recognition is not affected by preprocessing that drops some of the spatial bands, these partial bands are attenuated before image coding. The pre-processing of the luminance / chrominance separation type video signal is executed by using the filter. The present invention has a remarkable effect that it is possible to reduce the amount of image code that cannot be achieved by the preprocessing of the prior art by the attenuation of a specific partial band.

  When applying temporal LPF to the blue-yellow component of the color difference signal included in the input video signal, a filter with a cut-off frequency of F (Hz) is used. F is a subjective experiment of human visual and perceptual characteristics. According to the above, it was found that about 2 Hz is preferable from the balance between the degree of degradation of video and the effect of preprocessing as information amount reduction in encoding. When the cut-off frequency is lower than about 2 Hz, the color component is too blurred, and the deterioration of the image as a whole becomes conspicuous when combined with the luminance. On the other hand, when the cut-off frequency is higher than this, the effect of the preprocessing as the information amount reduction becomes small. It should be noted that if it is in the range of at least 2 ± 0.5 Hz, it can be said to be around 2 Hz, and it is clear that a better result than the conventional pretreatment can be obtained in this range.

  In addition, when applying spatial LPF to the blue-yellow component of the color difference signal included in the input video signal, a filter with a cutoff frequency of C (cycles / image) is used. According to the characteristic experiment, it was found that 3cycles / image is suitable. If the cut-off frequency is lower than around 3 cycles / image, the color components will be too blurred, and the overall degradation of the image will be noticeable when combined with the brightness. On the other hand, when the cut-off frequency is higher than this, the effect of the preprocessing as the information amount reduction becomes small. It should be noted that if the range is at least 3 ± 0.9 cycles / image, it can be said to be around 3 cycles / image, and in this range, it is clear that better results can be obtained than the conventional preprocessing.

  In addition, when temporal BEF is applied to each luminance / color difference signal included in the input video signal, a filter having a low cut-off frequency of F1 (Hz) and a high cut-off frequency of F2 (Hz) is used. According to subjective experiments on visual and perceptual characteristics, it was found that F1 is preferably around 2 Hz (2 ± 0.5 Hz) and F2 is around 6 Hz (6 ± 0.5 Hz). When the low-frequency cutoff frequency F1 is lower than about 2 Hz, the color and luminance components are excessively blurred, and the deterioration of the image as a whole becomes conspicuous. On the other hand, when the low cut-off frequency F1 is higher than this, the effect of the preprocessing as the information amount reduction becomes small. Further, when the high-frequency cutoff frequency F2 is lower than around 6 Hz, the effect of the preprocessing as the information amount reduction becomes small. On the other hand, when the high-frequency cutoff frequency F2 is higher than this, deterioration of the image as a whole becomes conspicuous due to excessive cutting of information.

  In addition, when spatial BEF is applied to each luminance / color difference signal included in the input video signal, a filter having a low cutoff frequency of C1 (cycles / image) and a high cutoff frequency of C2 (cycles / image) is used. However, according to the subjective experiment of human visual and perceptual characteristics, C1 should be 3cycles / image (3 ± 0.9cycles / image) and C2 should be around 8cycles / image (8 ± 0.9cycles / image). I understood. When the low-frequency cutoff frequency C1 is lower than around 3 cycles / image, the color and luminance components are too blurred, and the overall deterioration of the image becomes conspicuous. On the other hand, when the low cut-off frequency C1 is higher than this, the effect of the preprocessing as the information amount reduction becomes small. In addition, when the high-frequency cutoff frequency C2 is lower than about 8 cycles / image, the effect of the preprocessing as the information amount reduction becomes small. On the other hand, when the high-frequency cutoff frequency C2 is higher than this, deterioration of the image as a whole becomes conspicuous due to excessive cutting of information.

  In addition, when performing temporal HPF on the luminance signal included in the input video signal and performing preprocessing for superimposing the temporal DC component on the signal, a filter having a cutoff frequency of F3 (HZ) is used. According to human visual and perceptual characteristics, it was found that F3 is 4 to 6 Hz, preferably around 5 Hz (5 ± 0.5 Hz), although it depends on the desired quality and type of video.

  It is also possible to carry out a combination of some of these pretreatments. Even when combining several, it is desirable to use the cut-off frequency determined based on the above subjective experiment, because the smooth motion impression will be lost if the low / medium frequency region is dropped too much. .

1 Input means 2 CPU
3 Memory (RAM)
4 Digital Filter 5 Output Unit 6 Filter Information Storage 7 Program Storage 8 Bus Line 10 Signal Processing Control Program 11a, 11b, 11c,... Signal Processing Program

Claims (3)

Luminance signal and blue - the color difference signal and red yellow component - green luminance color difference separation type video signals comprising a color difference signal component as an input, pre-assuming the encoding in the subsequent processing the input signal to the facilities to video A signal preprocessing method,
Inputting a luminance / chrominance separation type video signal;
A pre-processing step of applying a spatial low-pass filter having a cutoff frequency of 3 ± 0.9 cycles / image only for the blue-yellow component of the color difference signal included in the input luminance / chrominance separation type video signal;
Blue was subjected to pretreatment - red was not subjected to the color difference signal preprocessing of the yellow component - and a color difference signal of the green component, and organic and outputting the luminance and color difference separation type video signal input in the same format A video signal pre-processing method. An input luminance color difference separation type video signals, a coding processing facilities to video signal pre-processing device to the input signal prior to assuming the later,
An input means for inputting a luminance / chrominance separation type video signal;
Pre-processing means for applying a spatial low-pass filter having a cutoff frequency of 3 ± 0.9 cycles / image only for the blue-yellow component of the color difference signals included in the input luminance / color difference separation type video signal;
Output means for outputting a luminance / chrominance separation type video signal of the same format as the input, including the pre-processed blue-yellow component color difference signal and the unprocessed red-green component color difference signal; video signal pre-processing device, characterized in that that.   A video signal preprocessing program for causing a computer to execute the video signal preprocessing method according to claim 1.

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