JP3450846B2 - Broadband color image signal transmitting device and receiving device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband color image signal transmitter and receiver for band-compressing and transmitting a wideband color image signal by multiple offset subsampling between fields and frames, and more particularly,
The transmission image quality of a wideband color image signal in a moving image area is improved based on knowledge of physical characteristics and visual characteristics of a moving image.

[0002]

One of the bandwidth compression transmission system due to multiple subsampling BACKGROUND ART wideband color picture signal, MUSE system according to the development of the present inventors (Mu ltiple S ub-
Nyquist Sampling E ncoding
There is a wideband color image signal sub-sample transmission system called System), which has been used for experimental broadcasting of high-definition color television in Japan as an excellent band compression narrowband transmission system for wideband color image signals.

The basis of band compression narrow band transmission in this MUSE system is to perform subsampling by making the positions of sample points different between adjacent lines, fields or frames, and to use as few sample values as possible. A large amount of image information is transmitted, and aliasing distortion mixed in a reproduced image due to subsampling is efficiently removed in advance by appropriate band limitation by a prefilter in an encoder.

However, the sub-sampling in the MUSE system adopts a fixed density sampling system for performing sub-sampling at a predetermined sample rate for both moving images and still images, in principle between lines, between fields and frames. Although sub-sampling is performed in between, actually, a slightly complicated sub-sampling method is adopted by combining various sample rates.

As a result, the sampling pattern of the transmission signal transmitted from the encoder forms a five-point sample pattern in which the arrangement of the sample points in each field makes a round in four fields, and the number of samples in each field is reduced as much as possible. On the other hand, in the decoder, with respect to the sample values of the transmitted five-eye pattern, in the still image area, all the sample values of four fields in which the pattern is completed are used for interfield and frame. The original image is reproduced almost completely by interpolating the sample values between the two. However, in the moving image area, the image content is reduced to 1 / field between fields as the image moves.
Since a time difference of 60 seconds occurs, interpolating interpolation between fields cannot be performed, and interpolating interpolation between fields, that is, between lines is performed only on the sample value of one field for each field.

For details of the MUSE system, Japanese Patent Application No. 58-194,115 filed by the present applicant (US Pat. No. 4,741).
No. 5,459) and Japanese Patent Application No. 60-106,132 (U.S. Pat. No. 4,69).
No. 2,801)) and documents relating to issuance of the applicant: NHK Laboratory Note No. 348, "Concept of
the MUSE System and it's P
Although described in “rotocol”, the outline of the MUSE encoder related to the gist of the present invention will be described here with reference to FIG.

The MUSE system engine having the schematic structure shown in FIG.
For coders, high-definition color television
That is, so-called high-definition primary color image signals R, G,
B has an upper band limit of 21 MHz to 22 MHz.
Low pass filter (LPF) 1_R , 1_G , 1_B Through
And analog / digital (A / D) converter 2_R , 2
_G , 2_B The clock rate of 48.6MHz.
Digitalized, and also via the gamma correction circuit 3 in common
The three primary color image signals R, G, B are led to the matrix circuit 4.
Luminance signal Y and two types of color difference signals C are matrixed.
₁ , C₂ And the luminance signal Y is directly converted to the TCI encoder.
And the color difference signal C₁ , C ₂ To it
Each of them has a low-frequency treatment band with a bandwidth upper limit of 8.1 MHz.
Filter (LPF) 5_C1, 5_C2Same TCI Enco through
Supply to the feeder 6.

The TCI encoder 6 is for converting the luminance signal Y and the color difference signals C ₁ and C ₂ into a single time series signal by subjecting the time axis compression and time division multiplexing to the color difference signals C ₁ and C. _After compressing the time axis of ₂ , the line-sequentially combined combination is inserted into the horizontal blanking period of the luminance signal Y, and the three signals are time-division multiplexed.

The time-series image signal extracted from the TCI encoder 6 is separated into a still image system S and a moving image system M,
The time-series image signal of the still image system S is guided to the inter-field pre-filter 7 to remove the signal component in the frequency domain which causes aliasing distortion due to the subsequent sub-sampling, and then to the inter-field offset sub-sampler 8. ,
Inter-field offset sub-sampling is performed at a sample rate of 24.3 MHz, and the output sub-sampled sequence image signal is passed through a low-pass filter (LPF) 9 having a band upper limit of 12 MHz and a sample rate converter 10
And sample rate from 48.6MHz to 32.4
After being converted to MHz, it is supplied to the mixer 13.

On the other hand, the time-series image signal of the moving image system M is guided to the intra-field pre-filter 11 to remove in advance the signal component in the frequency domain which causes aliasing distortion due to the subsequent sub-sampling operation, and is then sample-rate converted. To the sampler 12 and change the sample rate from 48.6MHz to 32.4M.
After being converted to Hz, it is supplied to the same mixer 13.

In the mixer 13, the time-series image signals of the still image system S and the moving image system M are appropriately mixed according to the motion detection result of the motion detector 14 separately provided in the encoder, and the mixed output thereof is output. The time-series image signal is guided to the line / frame offset subsampler 15 and subjected to the frame / line offset subsampling by a five-eye pattern at a sample rate of 16.2 MHz to form a MUSE format sample sequence image transmission signal.

The encoder in the MUSE system, which is recognized as a suitable example of the wideband color image signal sub-sample transmission system, is basically constructed as described above with reference to FIG. The sub-sample transmission mode is divided into a still image transmission mode and a moving image transmission mode according to the presence / absence of image movement and the size, and both are mixed at an appropriate ratio according to the detection result of the image movement,
Alternatively, the two may be appropriately switched so that the original image can be reproduced almost faithfully with the optimum image quality. In the still image transmission mode, the sampling pattern that makes a cycle of four field cycles is used for inter-field / inter-frame The original image is almost completely reproduced by performing interpolation, and in the moving image transmission mode, the image quality of the original image is substantially reproduced by interpolation in the field while avoiding the time difference between fields of the image content. There is.

[0013]

Therefore, in the encoder having the schematic configuration shown in FIG. 1, the pass band characteristics of the pre-filters 7 and 11 for limiting the transmission bands of the still image signal and the moving image signal are respectively set. The video transmission mode is basically band-limited on the assumption that simple intra-field signal processing is performed only on image sample values for each field. Therefore, in the reproduced image by interpolation in the corresponding field, although the required fineness is visually relaxed due to the movement of the image, there is a deterioration in image quality such as blurring due to the lack of the image information amount. There was a problem.

An object of the present invention is to solve the above-mentioned conventional problems and to deteriorate the transmission image quality which has occurred in the sub-sampling transmission system having the conventional basic structure, in particular, the moving image mainly based on the intra-field signal processing. It is an object of the present invention to provide a wideband color image signal transmitting apparatus and a receiving apparatus capable of remarkably improving the deterioration of the transmission image quality that has occurred in a region by variously examining it from various viewpoints.

[0015]

SUMMARY OF THE INVENTION In view of various findings obtained from the development of the MUSE transmission method and the experimental broadcast to be read, the inventors of the present invention transmitted image quality in sub-sample narrow band transmission of wide band color image signals. There is room for improvement in various aspects, especially from the viewpoint of improving transmission image quality in the moving image area, and the physical and visual factors of image quality deterioration are investigated. Mainly due to the intra-field signal processing that has been conventionally performed on the image signal, based on the new knowledge that the signal processing performed on the image signal in the moving image tilt region, inter-field processing,
In particular, a wideband color image signal transmission device and a reception device having a configuration in which improvement measures adapted to various factors causing image quality deterioration are added respectively, based on the introduction of inter-field signal processing of the form completed in frame units. Invented

That is, first, as a first cause of image quality deterioration, a frequency of 1/2 of the frame frequency of 15 Hz.
There is a flicker of and due to the simple in-field filter signal processing that has been conventionally performed on the image signal in the moving image area,
The specific spectral distribution in the horizontal and vertical spatial frequency domain that does not contribute to the moving image reproduction that occurs during the sampling process is expanded in the vertical frequency axis direction in the vertical frequency band without any limitation, and the conventional hardware that actually processes the signal is perfect. However, the image quality is remarkably deteriorated because it appears in the reproduced moving image as aliasing distortion. It is possible to improve the resolution of the reproduced moving image by accurately removing the specific component in the spatial frequency domain that causes the flicker remarkably by the inter-field signal processing.

Next, as a problem common to each of the second and subsequent factors that cause image quality deterioration, the amount of reproduced moving image information is insufficient due to the intra-field signal processing that has been conventionally performed on the image signal in the moving image area. However, it has been found that under appropriate conditions adapted to each factor, the inter-field processing introduced in the signal processing in the moving image area can appropriately improve the image quality deterioration caused by each factor.

That is, as the second factor causing the image quality deterioration, the definition of the reproduced color image in the moving image region is inherently deteriorated due to the lack of the amount of image information to be interpolated in the moving image region to be subjected to the in-field signal processing. I was doing
Conventionally, in the moving image area, inter-field offset sub-sampling, frequency band limitation to prevent aliasing distortion, and interpolation interpolation at the time of reproduction are applied to the color difference signal, which has halved the baseband band compared to the still image area. By completing each frame, the frequency band of the color difference signal was expanded and it was possible to improve the reproduction quality of color moving images.

As a third cause of image quality deterioration, the color image signal in the moving image area subjected to the in-field signal processing is not only the color difference signal transmitted with the baseband half-destructed but also the luminance signal. Although the resolution was visually insufficient, in the range where the movement of the image in the vertical direction is small, the luminance signal is also subjected to the in-frame completion signal processing between the odd and even fields,
By obtaining a replayed moving image with a resolution intermediate between that of a still image and a moving image with large vertical movement, further improvement of the overall image quality could be achieved.

That is, in the wideband color image signal transmitting apparatus of the present invention, at least the luminance signal component of the wideband color image signal subjected to the primitive sampling has an offset value between lines or frames which makes a cycle of two frames.
In a wideband color image signal transmitting apparatus for transmitting the wideband color image signal band-compressed by performing offset sub-sampling according to a sample pattern, the apparatus includes an offset sub-field between fields for an image signal of a moving image. A field offset subsampler for sampling and a color difference signal vertical frequency band limiting circuit block connected to the input side of the field offset subsampler, wherein the color difference signal vertical frequency band limiting circuit block is connected in series. Two connected field memories, a switcher for switching and outputting each input / output of the field memory in a field cycle, and an input / output signal of the field memory switched by the switcher is input to offset between the fields.・ With subsampling A vertical frequency band limiting filter for reducing aliasing distortion of a color difference signal generated in a reconstructed image, and a color difference signal vertical frequency band limiting circuit block provided in each processing system of two types of color difference signals. It is a thing.

Also, the wideband color image signal receiving apparatus of the present invention receives the band-compressed wideband color image signal transmitted from the wideband color image signal transmitting apparatus and outputs the wideband color image signal before being band-compressed. In a wideband color image signal receiving device to be reconstructed, the device performs interpolation of sample values between fields for each of two types of color difference signals for an image signal of a moving image. An interpolation interpolation circuit block is provided, and the color difference signal vertical direction interpolation interpolation circuit block includes two field memories connected in cascade, and at least two types of color difference signal bands in frame units composed of odd and even fields. Each input / output of the field memory is transmitted / received so as to complete the signal processing of the limit and the interpolation of the sample value. And a vertical direction interpolation interpolation filter for inputting the input / output signal of the field memory switched by the switcher and performing interpolation of sample values between the fields. It is characterized in that it is a color difference signal vertical interpolation circuit block provided in each processing system of two types of color difference signals.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments of the invention with reference to the accompanying drawings. The present invention according to claims 1 and 2 is particularly concerned with paragraph [0] in the present specification.
044] to paragraph [0067].

The signal processing system for moving image signals in the high-definition broadcasting system such as the MUSE system is generally the second conventional system.
It is configured as shown in the figure. That is, for example, MU
In the encoder on the transmission side in the SE method, an input image signal having an original sample frequency of 48.6 MHz is sample-rate converted via a low-pass filter 21 in the horizontal frequency domain having a transmission frequency sample frequency of 16.2 MHz as the upper limit of the pass band. The sampling frequency for inter-frame offset sampling is 32.4 M, which is suitable for transmission of a moving image in which an image changes between frames by dropping the original sampling frequency of 48.6 MHz for high definition transmission to 2/3.
Convert to Hz. Then, the sample moving image signal is supplied to the intra-field pre-filter 23, and band limitation for removing in advance the high frequency component near the sample point that causes aliasing distortion due to sampling is performed in consideration of the image movement. Give in. Then, the sample video signal whose band is limited is applied to the line offset subsampler 24.
And further performs inter-line offset subsampling to extract a moving image signal for subsample transmission having a sampling frequency of 16.2 MHz.

On the other hand, in the decoder of the receiving and reproducing system,
The moving image signal for sub-sample transmission is supplied to the intra-field interpolation filter 25, and the sample value of the transmitted moving image signal is interpolated and interpolated in the field to obtain the sampling frequency 3
The sample moving image signal of 2.4 MHz is reproduced, and the sample moving image signal is supplied to the sample rate converter 26,
The sample circumference fatigue number is 32.4 MHz and the original sample frequency is 4
It is converted back to 8.6 MHz and restored to the form of the input image signal on the transmission side.

The spectrum distribution in the horizontal / vertical spatial frequency domain of the band-limited sample moving image signal supplied from the in-field pre-filter 23 on the transmission side to the line offset / subsampler 24 in the signal processing system having the above-mentioned configuration is shown in FIG. As shown in. That is, the horizontal frequency band of the sample moving image signal is determined by the horizontal low-pass filter 21 to have a transmission sample frequency of 16.2 MHz.
It is suppressed below, but regarding the vertical frequency band,
Sample point 1 on the horizontal frequency axis with the origin of coordinates as the vertex
Corresponding point on the vertical frequency axis with 6.2MHz 1125 / 2T
The right-angled triangular spatial frequency region connecting V lines is 1125
It does not invert in the direction of the vertical frequency axis alternately in the cycle of / 2 TV lines, so it is expanded without limitation.

When the sample moving image signal having such a spectral distribution is supplied to the subsampler 24 and line offset subsampling is performed, the spectral distribution is as shown in FIG. That is, if the original image signal contains high-resolution signal components that can be expressed only in a still image in excess of 1125/2 TV lines in the vertical frequency domain, black dots are included in the diamond-shaped spatial frequency band shown in FIG. Thus, vertical frequency signal components exceeding 1125/2 TV lines folded by the sampling carriers shown in FIG.

Since the aliasing signal component formed on the transmitting side of the moving image signal transmission processing system having the configuration shown in FIG. 2 is removed by the interpolation filter 25 on the receiving and reproducing side, in principle, the reproduced moving image is reproduced. However, in the hardware that actually configures the signal processing system, the pre-filter 23 that removes the undesired signal component also interpolates the desired signal component in the hardware that actually constitutes the signal processing system. Since it is difficult to realize the characteristics of the filter 25 completely in accordance with the principle, such a folded signal component, in particular, a folded signal component folded back on the horizontal frequency axis of the coordinate origin 0 and in the vicinity of an odd multiple of 1125/2 TV lines in the vertical frequency. Is not completely removed,
Appearing as aliasing distortion in the reproduced moving image, flickers of 15 Hz, which is 1/2 of the frame frequency, occur and the reproduced image quality is significantly deteriorated. Therefore, removal of the aliasing distortion appearing in the reproduced moving image has been a conventional problem to be solved.

In the present invention, the above-mentioned conventional problems are solved as follows. According to the present invention, it is possible to easily compare the configuration example of the wideband color image signal transmitting device and the receiving device, which is composed of the transmitting side encoder and the receiving / reproducing side decoder, which transmit the sample moving image signal, with the conventional configuration shown in FIG. As shown in FIG. The transmitting device and the receiving device according to the present invention having the configuration shown in FIG. 5 are obtained by inserting spatial frequency filters A and B having a configuration surrounded by a chain line into an encoder and a decoder, respectively, in the conventional configuration shown in FIG. Is.

In the transmitter and the receiver according to the present invention shown in FIG. 5, the intra-field pre-filter 23 is used.
The band-limited sample moving image signal obtained from the above is supplied to the horizontal low-pass filter 27 in the spatial frequency filter A, and for example, half of the transmission sample frequency of 16.2 MHz is 8.1 MHz.
A low-frequency horizontal frequency component equal to or lower than z is extracted and supplied to the subtractor 28, and the input signal of the horizontal low-pass filter 27 is directly supplied to the subtractor 28 to form an equivalent horizontal high-pass filter. The extracted high frequency horizontal frequency component is supplied to the in-frame vertical filter 29,
Of the spectral distribution shown in FIG. 3, the vertical frequency 11
Vertical frequency 1 caused by the folding axis in 25
The filter output from which the high frequency horizontal frequency components existing in the range of 125/2 TV lines to 1125 × 3/2 TV lines and generating the main aliasing distortion is removed is supplied to the adder 30, and the low frequency horizontal from the horizontal low pass filter 27 is supplied. The filter output of the spatial frequency filter A obtained by adding the frequency component is applied to the line offset subsampler 24 as in the conventional case. Therefore, in the spectral distribution of the sample moving image signal input to the sub-sampler 24, the high frequency horizontal frequency component in the base band signal band shown by the bold line in the conventional spectral distribution shown in FIG. The spectral distribution is as shown by the thick line. As a result, the spectrum distribution of the moving image signal for sub-sample transmission extracted from the sub-sampler 24 is as shown in FIG. 7, and the sampling carriers indicated by black dots in the conventional spectrum distribution shown in FIG. The diamond-shaped folded signal component generation band at the center is limited to the elliptical band in the vicinity of each sampling carrier, and in particular, vertical frequencies of 1125/2 TV lines to 1125 × 3/2 TV lines that have conventionally generated the main folding distortion. The signal component in the frequency band is on the vertical axis and the vertical frequency is 1125 / 2T
Since it does not fold back to the vicinity of V lines, the fold back distortion appearing in the reproduced moving image is substantially removed, and it is 15 Hz as in the conventional case.
It is possible to obtain a stable reproduced moving image without flicker. The upper limit of the pass band of the horizontal low-pass filter 27 is preferably selected to be about 4 MHz to 8 MHz.

In the wideband color image signal transmitting device and the receiving device according to the present invention, as shown in FIG. 5, the horizontal low-pass filter 3 is also provided on the receiving and reproducing side.
1, the subtractor 32, the in-frame vertical filter 33, and the adder 34 interpose a spatial frequency filter B that has exactly the same configuration as the filter A on the transmission side and operates in exactly the same manner, and may occur during transmission. The aliasing distortion generation signal component is repeatedly removed in the same manner as on the transmitting side.

As a method for transmitting the image signal in a narrow band, all image information of the image signal is not transmitted one by one, but only sample values selected at appropriate intervals are transmitted, and at the time of reception and reproduction, it is appropriate between sample values. A sample transmission method is widely used in which all the image information of the original image signal is restored by interpolating various signal values, and as an image signal sampling method, one image at an appropriate time interval, that is, In addition to so-called temporal sampling for transmitting so-called frames or fields and spatial sampling by scanning lines forming one image, that is, a frame, there is widely used a sub-sample method for temporally and spatially sampling image information on each scanning line. It is used as described above. Among the sub-samples, the field offset sub-sampler is simple and easy for signal processing. Pull and line offset subsampling is used particularly often. In other words, the field offset sub-sample shifts the positions of the sampling points on the scanning line alternately between the odd and even fields that form one image, that is, the number of samples per field without changing the number of samples per frame. In addition, the line offset sub-sample is obtained by staggering the positions of the sample points on the scanning line between the lines forming the frame or field.

However, since the field offset sub-samples can interpolate sample points between arbitrary adjacent fields to each other for a still image, the definition can be reduced by a simple interpolation signal processing. It is possible to reduce the sample value transmission amount without doing so, and the reproduction image quality of the still image by the field offset subsample is superior to the line offset subsample, but for moving images, the image content differs between frames, so Interpolation cannot be performed between arbitrary adjacent fields, and the reproduction quality of a moving image by the field offset sub-sample is inferior to the line offset sub-sample. However, it has been found that, by performing appropriate inter-field signal processing, reproduction image quality above a certain level can be obtained even if field offset sub-sampling is used for moving images.

First, FIG. 8 shows a schematic configuration of a main part of a conventional sub-sample transmission signal processing system using field offset sub-samples suitable for sub-sample transmission of a still image signal. In the illustrated conventional configuration,
The input image signal is supplied to the transmission side encoder, first, the signal band is limited by the analog low-pass filter 41, and then the signal is guided to the analog-digital (A / D) converter 42, which is suitable for sub-sample transmission of image signals in general. A digital image signal quantized at the sampling frequency is supplied to an inter-field pre-filter 43 surrounded by a chain line to remove a high frequency signal component which causes a folding distortion generated in a received reproduced image due to sampling of the image signal. Band limitation is performed in order to suppress the occurrence thereof in advance.

That is, in the inter-field pre-filter 43 of the conventional structure, as shown in FIG. 8, a single field memory 44 is provided to output image signals of successive adjacent fields with one field interval at the input / output thereof. ,
For example, it is led to a digital filter 45 constituted by a transversal filter or the like, subjected to the above-mentioned band-limiting filtering action between successive adjacent fields, and the filtered output image signal of the inter-field pre-filter 43 is led to a field offset subsampler 46. Subsamples with offsets between odd and even fields are applied and then sent to the transmission path.

On the other hand, in the decoder on the receiving and reproducing side, the above-mentioned sub-sample transmission image signal is supplied to the inter-field post filter 47 shown by being surrounded by a chain line, and the sample value is interpolated between adjacent fields.

That is, in the inter-field post filter 47 of the conventional structure, the single field memory 48 is exactly the same as the inter-field pre-filter 43 on the transmitting side.
Is provided with a digital filter 4 for inputting / outputting image signals of successive adjacent fields with one field interval.
9, the sample value offset between the successive adjacent fields is interpolated and interpolated, and the filtered output image signal of the inter-field post filter 47 is guided to the digital / analog (D / A) converter 50 to be an analog image signal. The analog high-pass filter 51 restores and removes unnecessary high-frequency components, and extracts the reproduced output image signal.

Therefore, in the conventional sub-sampled transmission signal processing system shown in FIG. 8, both the inter-field pre-filter 43 and the inter-field post-filter 47 are input / output to / from the single field memories 44 and 48. Since the filtering operations for band limitation and interpolation are performed between the image signals of the adjacent fields extracted from each, the filtering operation between the fields is always performed between the current field and the field immediately before it. It will be. The filtering action for band limitation on the transmitting side and the filtering action for interpolation on the receiving / reproducing side are performed in the same state in response to each other on the transmitting side and the receiving / reproducing side by a filter having the same configuration. Is the basic principle, and as it deviates from the basic principle, it becomes difficult to faithfully restore the original image.

However, in the signal processing system of the conventional configuration shown in FIG. 8, both the transmitting side and the receiving / reproducing side always perform the filtering operation between the current field and the immediately preceding field as described above. Therefore, as shown in FIG.
On the sending side, sequential input fields ,,,-
Each of the image signals of the sequential transmission fields a, b, c, d, --- which has been subjected to the filtering action on the image signal of-, has two sequential input fields ,,,,,
And --- is a combination of the image signals. Further, on the receiving and reproducing side, the sequential reproducing fields α, β,
Each of the γ, δ, --- image signals is a combination of the image signals of the two successive transmission fields a and b, b and c, c and d, and d and-, respectively. Therefore, when viewed through the entire signal processing system, the sequential reproduction fields α, β,
The image signals of γ, δ, --- are respectively three sequential input fields ,,,,, and ---,-
The image signals of the input and output image signals do not correspond to each other in the signal processing system as a whole. In particular, in a moving image in which the image information for each frame changes from moment to moment, such inconsistency in input / output image information directly deteriorates the image quality of the reproduced moving image.

A schematic configuration of a main part of a signal processing system in the wideband color image signal transmitting apparatus and the receiving apparatus of the present invention which eliminates such deterioration of the reproduced moving image corresponds to the conventional configuration shown in FIG. This is shown in FIG. As can be seen by comparing FIG. 10 and FIG.
The difference or improvement from the conventional configuration shown in FIG. 8 of the signal processing system according to the present invention shown in FIG.
3 and a single field memory 44 and 48, which are conventionally provided in the post filter 47 on the receiving and reproducing side,
Two field memories 44, each connected in cascade.
1, 44-2 and 48-1, 48-2, image signals of two adjacent fields, which have been conventionally taken out from the input / output of the single field memories 44 and 48, respectively, are replaced by the prefilter 43 and the postfilter 47. When the current field in the input of is an odd field, the image signals of the odd and even fields which form one frame one frame period before in the input and output of the field memories 44-2 and 48-2 are taken out as a conventional adjacent field,
When the current field is an even field, the image signals of the odd and even fields that form one frame at the input and output of the field memories 44-1 and 48-1 are taken out as the adjacent fields of the slave, and the odd and even fields are alternated every such field cycle. The combination of fields is switched by the change-over switches SWl and SW2 and supplied to the digital filters 45 and 49, respectively.

Therefore, in the signal processing system of the transmission system according to the present invention, both the transmitting side and the receiving / reproducing side constantly transmit and receive the filtering action for band limitation and interpolation between the odd and even fields forming one frame. Since it is completed every unit frame period, as shown in FIG. 11 in the related art, as shown in FIG. 9 in the related art, on the transmission side, two sequential input fields, and each image of --- The signals are combined and filtered to form image signals of two successive transmission fields a and b, c and d, ---, and
On the receiving / reproducing side, the image signals of the two successive transmission fields a and b, c and d, --- are combined and filtered, respectively, and the sequential reproduction fields α and β, γ and δ, --- are applied. Image signals are formed respectively. Therefore, when viewed through the entire signal processing system, the respective image signals of the sequential reproduction fields α and β, γ and δ, --- are respectively two sequential transmission fields a and b, c and d,-on the transmission side. Corresponding to-, two consecutive input fields ,,,-
-Because each image signal of is combined,
The quality of the reproduced moving image can be improved.

Although the reproduction quality of a still image by the field offset sub-sample is superior to that of the line offset sub-sample, the moving image has different image contents between frames, so that interpolation between arbitrary adjacent fields is performed. It was mentioned earlier that the image quality of moving images reproduced by field offset sub-sampling is inferior to that of line offset sub-sampling because interpolation cannot be performed. A field offset subsample is used for sampling transmission, and a line offset subsample is used for sampling transmission of a moving image or a moving image area in the same image. Under control,
Conventionally, a mixed sampling transmission system, that is, a so-called MUSET system or the like, which switches between the two in accordance with the presence or absence of image movement, has been developed.

However, in such a hybrid sub-sample transmission system, in order to obtain motion signals for controlling the above-mentioned adaptive switching on the transmitting side and the receiving / reproducing side, respectively.
Motion detection of each image separately, or
It is necessary to transmit a motion signal representing the motion of the image detected on the transmission side to the reception side together with the sample image signal. Moreover, it is necessary to provide two signal processing systems, one for a still image and one for a moving image, on both the transmitting side and the receiving / reproducing side, and to switch between them. Furthermore, a still image area and a moving image area are mixed in the same image. In that case, it is necessary to make the switching inconspicuous, and not only each signal processing device becomes large-scale, but also the motion detection of the image is not appropriate, there is an erroneous detection, and the switching of the signal processing system is performed. If is not appropriate, there are many problems such as a new image quality deterioration in the reproduced image.

The improvement of the image quality of the moving image has been described with reference to FIGS. 10 and 11, but since signal processing can be performed on a still image with a predetermined image quality, in the present invention,
The above-mentioned conventional problem is solved as follows, and the transmitting side and the receiving / reproducing side are respectively provided with only one signal processing system having the configuration shown in FIG. Therefore, it is not necessary to detect the motion of the image for the switching control, and although it is a small-scale signal processing system, it is possible to transmit the image while maintaining the image quality of a certain level or more in both the moving image area and the still image area. .

Now, in the above-mentioned MUSE system developed as a high definition color television broadcasting system, a band of 20 MH constituting a wide band high definition color image signal.
In order to enable FM transmission of the z luminance signal and two types of color difference signals each having a band of 7 MHz with a transmission bandwidth of 27 MHz for one channel of satellite broadcasting, each component signal is digitized and appropriately subsampled. Axial compression
Time division multiplexing, and baseband of each component signal is 8MH
Narrower band transmission is performed by limiting to z or less.

The sub-sample transmission of the color image signal in the MUSE system is based on the principle of offset sampling by a sampling pattern that makes a cycle of two frames, that is, four fields. For the still image area, field offset sub-sampling is performed between successive fields. A required high-definition color image can be reproduced by sampling and interpolation at the time of reproduction thereof. However, in the moving image area, since the image content differs between frames due to the movement of the image, conventionally, the same field is exclusively used. The line offset subsampling and the interpolation at the time of its reproduction were performed.

Therefore, since the amount of image information to be interpolated and interpolated in the moving image area is remarkably small as compared with that in the still image area, the definition of the reproduced color image in the moving image area is inherently reduced. In the image area, the base band of the color difference signal is limited to about 4 MHz.

In the present invention, the above-mentioned conventional problem is solved as follows, and the amount of image information to be interpolated and interpolated at the time of reproducing the sub-sampled image signal is increased and the frequency band of the color difference signal is expanded. The playback quality of color moving images has been improved.

First, FIG. 12 shows a conventional configuration of a color difference signal processing system, that is, an encoder and a decoder for sub-sample transmitting a color difference signal in a moving image area of a MUSE system color image signal. In the encoder for color difference signal processing according to the conventional configuration shown in the drawing, a high-definition color image signal, that is, a so-called high-definition image pickup output three primary color RGB signal is converted into an analog / digital (A / D) converter 6.
1 and digitize it by a 48.6 MHz clock signal, and lead it to a matrix circuit 62 to form a luminance signal (Y) and color difference signals (RY) and (BY). The matrix output color difference signals (RY) and (BY) excluding the luminance signal (Y) that is separated and separately processed are guided to the sub-sampler 64 via a low pass filter (LPF) 63 having a band upper limit of 8 MHz. , 16.2MHz clock frequency under the control of 16.2MHz clock signal
To perform sub-sampling in the horizontal direction, and to introduce two color-difference signal sample sequences (RY) and (BY) alternately line-sequential to the TCI circuit 65 to perform time-axis compression / time-division multiplexing to obtain luminance. It is converted into the form of a time series signal that can be multiplexed in the horizontal blanking period of the signal.

In the conventional color difference signal encoder, the color difference signal sample sequence is guided to the field offset subsampler 66 to reduce the sample rate to 8.1 MHz by the interfield offset, and
Under the control of a conventional motion detection output (not shown), the color difference signal sample sequence in the still image area is separated and separately processed, and the sample rate in the moving image area is 8.1M.
The low-pass filter (LP
F) Guide to 67 to limit the frequency band to 4 MHz, and further guide to two-dimensional filter 68 to limit the horizontal and vertical spatial frequency bands.

For the color-difference signal sample train in the moving image area in which the band is limited by the conventional configuration shown in FIG. 12, line-sequential alternating signals of the color-difference signals in the MUSE color image signal with 1125 scanning lines are used. Based on the morphology and the sample rate of 8.1 MHz, the position of the sub-sample carrier in the spatial frequency domain is 11 in the vertical direction.
As shown in FIG. 13, the spatial frequency band capable of transmitting the color difference signal is 25/2 TV lines, 8.1 MHz in the horizontal direction, and is limited by the line segment connecting the midpoints of the sub-sample carrier intervals. , 1 on the vertical axis with the coordinate origin
The band is a triangle having 125/4 TV points and 4 MHz points on the horizontal axis as vertices. It should be noted that FIG. 13 and similar drawings described later, FIGS. 15 and 17 to 2
FIG. 0 shows an image signal in a line-sequentialized form.

The band-limited color difference signal sample sequence of the moving image area is guided to the mixer 69 to be mixed with the separately processed color difference signal sample row of the still image area, and the mixed output color difference signal is guided to the multiplexing circuit 70. After being separately multiplexed in the horizontal blanking period of the luminance signal, the color image signal sub-sample sequence is guided to the frame offset sub-sampler 71 and converted into a sample pattern of one frame of two frames which is a sub-sample transmission mode of the MUSE method. , Analog transmission via a digital / analog (D / A) converter 72.

On the other hand, in the color difference signal processing decoder of the conventional configuration shown in FIG. 12, the encoder performs signal processing opposite to that described above to perform high-definition three primary color RG.
Reproduce B signal. That is, the time-axis compression / time-division multiplex sub-sample sequence of the color image signal which is analog-transmitted as described above is converted into an analog-digital (A / D) converter 73.
To a digital signal again, and the converted output subsample sequence is switched to separate the luminance signal and the color difference signal of the still image area and process them separately as in the encoder, and the color difference of the moving image area is also processed separately. The signal sub-sample sequence is sequentially guided to a two-dimensional filter 74 and a low-pass filter (LPF) 75 with a band upper limit of 4 MHz, and the sub-sample sequence is interpolated by the same band limitation as in the encoder. 76
To the inverse TCI circuit 77, and the mixed output color difference signal sub-sample sequence is mixed with the still image area color difference signal sub-sample sequence that has been separately processed. Is restored to the original signal form, the color difference signals (RY) and (BY) are extracted and led to the inverse matrix circuit 78, and the separately processed luminance signal is added to restore the form of the three primary color RGB signals. It is taken out as a reproduction output through a digital / analog (D / A) converter 79.

FIG. 12 shows an example of the configuration of the color difference signal processing system according to the present invention which is improved so as to expand the transmittable spatial frequency band of the moving image area in comparison with the color difference signal processing system of the conventional configuration described above. The same blocks as those in the configuration are designated by the same reference numerals, and the same arrangement is shown in FIG.

It can be understood by comparing FIGS. 12 and 14 with each other.
As described above, the difference between the configuration according to the present invention and the conventional configuration is
Circuit block for vertical frequency band limitation
81 _R , 81_B , 82_R , 82_B , 83_R , 83_B And T
It is only the arrangement of the CI circuit 65, and
In addition, the vertical interpolation circuit block 85_R , 85
_B , 86_R , 86_B , 87_R , 87_B And frame interpolation
New circuit 84 and interpolation filter 88 and inverse TCI circuit
77 arrangement, and each other circuit block
Even in the configuration according to Ming, all
Since they all work in the same manner, the configuration of the present invention will be described below.
Only the differences from the prior art will be described.

In the encoder according to the present invention, the vertical frequency band limiting circuit block and the TCI circuit 6 are provided.
5 and the arrangement order of the color difference signal sample sequence (R−
Y) and (BY) are taken out in parallel, the color difference signals in the still image area are separated for separate processing, and the color difference signals (RY) and (BY) in the moving image area are put in parallel. As it is, they are respectively led to separate vertical frequency band limiting circuit blocks, and the spatial frequency band in the vertical direction of the color difference signal sub-sample trains (RY) and (BY) having a horizontal sample rate of 16.2 MHz is divided into two fields. 1125 / 8T in which each frame is processed and completed within each frame
Limit each to V books.

That is, the color difference signal sample trains (RY) and (BY) from the subsampler 64 are connected to the field memories 81 _R and 82 _R in series and 81 _B and 82 _B in series for each field. To the respective a terminals of the changeover switches SW1 _R and SW1 _B , and to the respective b terminals of the changeover switches, the color difference signal sample sequences delayed by two fields from the field memories 82 _R and 82 _B are supplied. (R-
Y) and (B-Y), and simultaneously switch each switch SW1 _R and SW1 _B in the field cycle.
The upper limit of the pass band is set to 1125 for the switching output of each switch and the intermediate point output of each field memory connected in series.
/ 8 TV leads to vertical filters 83 _R and 83 _B.

Therefore, for example, the color difference signal (RY)
Field memory 81 for supplying_R, 82_R Series connection
The color difference signal (RY) sequential filters will be described.
The fields are # 1, # 2, # 3, # 4, # 5 ---
Field memory 81_R Input terminal of the field memory
81_R , 82_R The intermediate terminal of the field memory 82
_R The output terminal of is. Then, first, changeover switch
Switch SW1_R Each memory terminal when is connected to the terminal a
,,, the color difference of fields # 3, # 2, and # 1 sequentially
If the signal (RY) is present, the vertical filter
83_R Is the memory terminal and the
The color difference signals (RY) of fields # 3 and # 2 are supplied.
Then, in the next field period, the changeover switch SW
1_R When connecting to the b terminal,
When memory pin and field appearing in #
The color difference signals (RY) of 3 and # 2 are again filtered by the vertical filter.
83 _R Will be supplied to. Therefore, feel
It is assumed that the frames # 2 and # 3 form the same frame.
Then, the vertical filter 83_R Always have the same frame
The color difference signals (RY) of the two fields that compose the
Vertical filter 83_R In
Always the sample rate in two consecutive fields
Pair with 16.2MHz color difference signal sample string (RY)
However, the limitation of the vertical spatial frequency band is completed for each frame.
The frequency band limitation will be
The same is true for the color difference signal sample sequence (BY) at the same time.
Will be applied in the same way.

Color-difference signal sample sequences (RY) and (B) respectively subjected to such frequency band limitation on a frame-by-frame basis.
-Y) is supplied in parallel to the TCI circuit 65 from the vertical filters 83 _R and 83 _B, and color difference signal sample strings (RY) and (B-
When Y) is subjected to time-axis compression / time division multiplexing and converted into a line-sequential alternating signal form that can be inserted in the horizontal blanking period, the subsequent mixer 69 has the same signal form as in the conventional configuration shown in FIG. The time-series color difference signals of the moving image area exhibiting the above are supplied, and the transmittable spatial frequency band of the moving image area time-series color difference signals is as shown in FIG. It is doubled compared to the conventional frequency band shown in the figure.

The moving image area time-series color difference signal is subjected to the same signal processing as that in the conventional configuration shown in FIG. 12 after the mixer 69 and transmitted, but in the frame offset subsampler 71, Inter-field offset sampling, which also serves as frame offset sub-sampling, is performed in frame units.

On the other hand, in the color difference signal processing decoder having the structure according to the present invention, the time axis compression / time division multiplex sub-sample sequence of the color image signal analog-transmitted from the encoder is converted into an analog / digital (A / D) converter 73. The signal processing described above for frequency band limitation to prevent the occurrence of aliasing distortion due to subsampling in the encoder for the time series color difference signal after separating the luminance signal to be processed separately after Corresponding signal processing is performed, and interpolation interpolation is performed on the color difference signal subsample sequence.

That is, the time-series color difference signals from the A / D converter 73 are first guided to the frame interpolation circuit 84, and the fields in the frame offset subsampler 71 of the encoder, that is, the fields corresponding to the intraframe offset subsampling, are inputted. The interpolating interpolation is performed by the encoder so as to be completed on a frame-by-frame basis, and the time-series color difference signals subjected to the frame interpolating are subjected to the inverse TCI.
The circuit 77 is used to solve the time-sequential signal form of line-sequential alternating 1125/2 lines per frame, and two systems of color difference signals (RY) and (B- Y) The signal form is restored, and the vertical direction interpolation circuit block groups 85 _R , 85 _B , 86 _R , 86 _B , 8 _B each configured exactly like the vertical frequency band limiting circuit block in the encoder are provided.
Supply in parallel to 7 _R and 87 _B.

In these vertical direction interpolation interpolation circuit block groups, the vertical direction interpolation is performed in the form of being completed frame by frame by the circuit operation exactly the same as the vertical frequency band limitation in the encoder. Vertical filters 87 _R and 87 _B used for the interpolation are vertical low-pass filters (LPF) having a band upper limit of 1125/8 TV lines, which is exactly the same as the vertical filters 83 _R and 83 _B in the encoder.

As described above, in order to process the color difference signals of the two systems in parallel, the arrangement order of the interpolation interpolating circuit and the inverse TCI circuit 77 is changed from that of the conventional configuration shown in FIG. Color difference signals (R-Y) and (B-Y)
Are transmitted in parallel to the mixer 76, detected and transmitted by the encoder, or under the control of the motion detection output of the image detected by the decoder, separately processed color difference signals (RY) of the still image area (RY), ( B-Y) and the mixed output color difference signals (RY) and (BY) are introduced in parallel to the interpolation filter 88.

In the color difference signal processing system of the present invention shown in FIG. 14, the color difference signal sub-sample trains (RY), (B- The horizontal sample rate of Y) is 4 in the encoder subsampler 64.
Since it is still reduced from 8.6 MHz to 16.2 MHz, the mixed output color difference signals (RY), (B
-Y) is guided to the interpolation filter 88 to perform horizontal interpolation, and each sample rate is converted from 16.2 MHz to 48.6 MHz. The interpolation interpolation filter 88 is composed of a low-pass filter having a band upper limit of 8 MHz corresponding to the LPF 63 in the encoder. In addition, the color difference signals (RY) and (BY) having the sample rate of 48.6 MHz are converted into the inverse matrix circuit 7
8 primary colors R combined with separately processed luminance signal
Restores the form of the GB reproduction output signal. Subsequent signal processing is the same as in the conventional configuration shown in FIG.

Subsamples in the horizontal / vertical two-dimensional spatial frequency domain to the color difference signal sample sequence in the moving image domain when the signal processing according to the present invention described above with reference to FIG. 14 is applied to a high definition color image signal of the MUSE system. The position of the carrier and the transmittable spatial frequency range are as shown in FIG. 15 on the plane where the frequency on the time axis is zero, as in FIG. 13 showing the case of the conventional configuration. That is, since the horizontal interval between subsample carrier positions is the same as the horizontal subsample rate of 16.2 MHz, the horizontal frequency band is 8.
The number of samples, which is expanded to 1 MHz and can be used for signal processing of interpolation in the decoder, is doubled by performing the signal processing on a frame-by-frame basis.

On the other hand, the interval between the sub-sample carrier positions in the vertical direction is doubled as compared with the case of the conventional configuration shown in FIG. 13 because the signal processing in the vertical direction is performed in units of two fields. Since the upper limit of the vertical frequency range is halved to 1125/8 TV lines, the frequency range that can be transmitted in the two-dimensional spatial frequency domain is as shown in FIG. 15 and shown in FIG. It is twice as large as that of the conventional configuration.

Regarding the resolution in the time axis direction, 2
Since the signal processing is performed on a frame-by-field basis, it is halved compared to the conventional configuration. In general, for a luminance signal, when image processing with a field frequency of 60 Hz is performed on a frame-by-frame basis, the resolution in the time axis direction is halved, resulting in a resolution equivalent to 15 Hz. The bulk is lost and judder occurs. However, with respect to the color difference signal, the human visual characteristics with respect to the deterioration of the resolution in the time axis direction are deteriorated. Therefore, the color difference signal is subjected to signal processing in frame units to reduce the resolution in the time axis direction to 15 Hz. However, the deterioration of the color image quality is not visually recognized.

Further, according to the present invention, the image signal in the moving image area in which the motion is relatively small is subjected to inter-field offset subsampling and inter-field signal processing to limit the band for preventing aliasing distortion. By performing interpolation interpolation at the time of reproduction, a reproduction moving image having an intermediate resolution between a still image and a moving image with large movement is obtained, and the overall reproduction image quality is further improved. 16 (a) and 16 (b) are configuration examples of the encoder and the decoder of the wideband color image signal transmitting apparatus and the receiving apparatus according to the present invention in the above case.
Are shown respectively.

In the encoder shown in FIG. 16 (a), the luminance signal component of the input color image signal is guided to the analog / digital (A / D) converter 91 and digitized at a sampling frequency of 48.6 MHz, and then the band is converted. Upper limit 1
6.2 MHz horizontal low pass filter (LPF) 9
2 to the sampling frequency converter 93, the sampling frequency is converted from 48.6 MHz to 32.4 MHz, and the converted output luminance signal is the band upper limit 1125 / 2TV.
Through a vertical low pass filter (LPF) 94 to the sub-sampler 95, sample frequency 32.4 MH
z inter-field offset sub-sampling is applied to the sub-sampler 97 through a horizontal low pass filter (LPF) 96 having a band upper limit of 8.1 MHz, and the inter-frame and line offsets are applied at a sample frequency of 16.2 MHz.・ Subsampling is applied to the MU
A signal for sub-sample transmission is formed by the SE system five-eye sampling pattern, and the digital / analog (D /
A) Analog transmission via converter 98.

On the other hand, in the decoder shown in FIG. 16 (b), the sub-sampling transmission signal having the sampling frequency of 16.2 MHz is converted into an analog / digital (A / D) signal.
After being led to the converter 99 and digitized again, it is led to the inter-field interpolation circuit 100 and the field memory 101.
Inter-field interpolation is performed by exchanging signals for each field with, and the interpolated interpolation of the sample value at the position lost by offset subsampling, and then the horizontal low-pass filter (LPF) with a band upper limit of 8.1 MHz. 1
02 through 02 to the sub-sampler 103 and sample frequency 16.2 of the sample sequence subjected to inter-field interpolation interpolation
Bandwidth upper limit 1 after converting MHz to 32.4MHz
125/2 TV vertical low-pass filters (LP
F) 104 to perform vertical interpolation and
The sample sequence subjected to the interpolation in both vertical directions is guided to the sampling frequency converter 105, and the sampling frequency is 32.4.
MHz is returned to the original sample frequency of 48.6 MHz, and a horizontal low pass filter (LPF) 106 with a baseband upper limit of 16.2 MHz and a digital / analog (D /
A) It is taken out as a reproduction output luminance signal through the converter 107 sequentially.

Generally, with respect to the image signal in the moving image area, the image content is shifted not only between frames but also between fields, due to the movement of the image. It was done only by the line offset in the field,
When the motion of the image in the vertical direction, which is originally small in motion compared to the horizontal direction, is relatively small, as described above, the inter-frame signal processing is performed also on the luminance signal, and it is better than in the conventional reproduced moving image. It is possible to obtain a reproduced moving image with far superior resolution.

The position of the subsample carrier in the horizontal / vertical spatial frequency domain when the image signal is subjected to the line offset / subsampling in the field is as shown by the mark ● in FIG. When the interpolation is applied, the sub-sample carrier at the position indicated by X in FIG. 18 disappears. Therefore, other information can be multiplexed and transmitted at the position where the sub-sample carrier disappears.

Further, the reproducible frequency range in the spatial frequency domain when the intra-field interpolation interpolation is applied to the transmission sample sequence of the image signal subjected to the intra-field line offset sub-sample is, as described above, the 19th frequency range. Although it is a triangular range shown in the figure, the reproducible frequency range when inter-field interpolation is applied becomes a rectangular range shown in FIG. 20, which is twice as large as that when the conventional intra-field signal processing is applied. Expanded.

Further, in the image signal transmitted by the sample pattern that makes one cycle in two frames, which is the basic in the conventional sub-sample transmission, the fundamental frequency is 15 Hz, but the image signal subjected to the inter-field signal processing for each frame. In, the basic frequency is 30 Hz.

However, since the human visual characteristic is sensitive to the frequency component of 15 Hz, there is a drawback that the reproduced image signal transmitted by the conventional sample pattern that makes a cycle of two frames has a flicker of 15 Hz. On the other hand, when inter-field signal processing is performed, it is also excellent in that such flicker does not occur. Therefore, if inter-field interpolation interpolation is performed in the decoder regardless of the sub-sampling method in the encoder, it is 15 Hz. It is possible to suppress the occurrence of flicker.

Here, sample patterns at respective stages in the encoder shown in FIG. 16 (a) are shown in FIGS. 21 (a) to 21 (e). Incidentally, in the figure, a circle indicates an odd field sample pattern, and a circle indicates an even field sample pattern. In FIG. 21, (a) is an analog-digital (A / A) of a sample frequency of 48.6 MHz which is the basis of the MUSE system.
D) The original sample pattern in the converter 91,
(B) is a sample pattern in which the sampling frequency is converted to 32.4 MHz by the sampling frequency converter 93, and it is 1125 TV lines in the vertical direction and 3 in the horizontal direction.
Samples in the form of a square grid arranged at 2.4 MHz intervals.
It has a pattern.

FIG. 21 (c) shows the sub-sampler 9
5 is a sample pattern when inter-field offset subsampling is performed at a sampling frequency of 32.4 MHz in FIG.
Although it can be seen as a sample pattern of 6.2 MHz, it is regarded as a sample pattern in which the sample value is set to zero every other sample at a sample frequency of 32.4 MHz.

Further, FIG. 21 (d) shows the offset between the frame and the line in the subsampler 97.
FIG. 21 (e) shows a sample pattern of the MUSE transmission signal when sub-sampling is performed, and FIG. 21 (e) shows only the even field. 2
In the MUSE system transmission signal that makes a round in a frame,
The sample pattern shown in FIG. 21 (d) is inverted frame by frame.

As described above, the inter-field signal processing applied to the image signal of the moving image area in which the vertical motion is small is performed for two frame rounds to the image signal of the still image area, and the moving image area when the motion is large. When combined with the in-field signal processing applied to the image signal of, the reproduction image quality in the sub-sampling transmission system can be significantly improved as a whole.

[0080]

As is apparent from the above description, according to the present invention, the vertical frequency of 1125/2 TV lines to 1125 × 3/2 TV lines in the moving picture signal of the high-definition broadcasting system for sub-sample transmission, for example, the MUSE system is used. Horizontal high frequency signal component in the range is 0 MHz, 1125/2
Since there is no aliasing near the TV book, and it is possible to obtain a stable reproduced moving image without aliasing distortion, as a result, transmission that has been conventionally used for removing aliasing distortion for sub-sample moving images. Even when the pass bands of the pre-filter on the side and the interpolation filter on the reception / reproduction side are widened as compared with the conventional case, aliasing distortion is less noticeable, and the resolution of the reproduced moving image can be remarkably improved.

Further, inter-field signal processing of signal band limitation on the transmitting side and interpolating interpolation on the receiving / reproducing side for reducing aliasing distortion occurring in a reproduced image due to sub-sampling is performed between odd and even fields of each set, and transmission / reception is performed. Since each frame is completed correspondingly, there is no risk that the image information of the three input fields will be mixed in the reproduced image of each field, and the reproduced image quality, especially the reproduced image quality of the moving image in which the image information changes between frames, is It is significantly improved in comparison.

The signal processing in units of frames is
As described above, since a still image quality of a certain level or more can be obtained, it is possible to use only a single field offset / sub-sample signal processing system commonly for both moving and still images. In that case, not only the device can be downsized, but also the motion detection of the image, which was conventionally required for the switching control between the still image processing system and the moving image processing system, becomes unnecessary. It is possible to achieve such an effect.

Further, when sub-sampling a wide band high definition color image signal, the transmittable spatial frequency band of the color difference signal in the moving image area is doubled as compared with the conventional one to improve the reproduced color image quality of the moving image area. It can be remarkably improved as compared with the conventional one, and the compatibility with the conventional one can be maintained for both the encoder and the decoder in the sub-sample transmission.

That is, if the wideband color image signal sub-sample transmission system of the present invention is used, the resolution of the moving image area in high-definition broadcasting is improved, and if used in combination with the conventional transmission system of this kind, a finer high-definition signal can be obtained. Broadcasting becomes possible, or the configuration of the transmission system can be simplified while maintaining the conventional image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an encoder according to a conventional color image signal sub-sample transmission system.

FIG. 2 is a block diagram showing a schematic configuration of a conventional image signal sub-sample transmission system.

FIG. 3 is a diagram similarly showing a spectral distribution of an input image signal of a line offset subsampler in the conventional transmission system.

FIG. 4 is a diagram similarly showing a spectral distribution of an output image signal of the subsampler.

FIG. 5 is a block diagram showing a configuration example of a wideband color image signal transmitting device and a receiving device according to the present invention.

FIG. 6 is a diagram showing a spectral distribution of an input image signal of a line offset subsampler in the transmitter and the receiver of the same.

FIG. 7 is a diagram similarly showing a spectral distribution of an output image signal of the subsampler.

FIG. 8 is a block diagram showing a configuration of a signal processing system in a conventional image signal sub-sample transmission system.

FIG. 9 is a diagram similarly showing a mode of signal processing in the signal processing system.

FIG. 10 is a block diagram showing a configuration example of a signal processing system in the wideband color image signal transmitting apparatus and the receiving apparatus according to the present invention.

FIG. 11 is a diagram similarly showing a mode of signal processing in the signal processing system.

FIG. 12 is a block diagram showing a configuration of a color image signal sub-sample transmission system according to a conventional method.

FIG. 13 is a characteristic curve diagram showing a transmittable spatial frequency band of a moving image region color difference signal in the same sub-sample transmission system.

FIG. 14 is a block diagram showing a configuration example of a wideband color image signal transmitting device and a receiving device according to the present invention.

FIG. 15 is a characteristic curve diagram showing an example of a transmittable spatial frequency band of a moving image region color difference signal in the same sub-sample transmission system.

FIG. 16 is a block diagram showing a schematic configuration of an encoder and a decoder in the wideband color image signal transmitting apparatus and the receiving apparatus according to the present invention, respectively.

FIG. 17 is a diagram showing the position of a sample carrier in the spatial frequency domain of an in-field line offset / subsample transmission image signal.

FIG. 18 is a diagram showing the positions of sample carriers in the spatial frequency domain of an inter-field offset sub-sample transmission image signal.

FIG. 19 is a diagram showing a transmittable frequency band in a spatial frequency region of an in-field line offset / subsample transmission image signal.

FIG. 20 is a diagram showing a transmittable frequency band in a spatial frequency region of an inter-field offset / subsample transmission image signal.

21 is a diagram sequentially showing sampling patterns in respective units of the encoder and the decoder shown in FIG.

[Explanation of symbols]

21 horizontal low-pass filter (LPF) 22 sample rate converter 23 intra-field pre-filter 24 line offset subsampler 25 intra-field interpolation filter 26 sample-rate converter 27 horizontal low-pass filter (LPF) 28 subtractor 29 frames Inner vertical direction filter 30 Adder 31 Horizontal direction low pass filter (LPF) 32 Subtractor 33 In-frame vertical direction filter 34 Adder 41 Analog low pass filter 42 Analogue digital (A / D) converter 43 Prefilter 44- 1, 44-2 Field memory 45 Digital filter 46 Field offset subsampler 47 Post filter 48-1, 48-2 Field memory 49 Digital filter 50 Digital-analog (D / A) converter 5 Analog low-pass filter 61 Analog-digital (A / D) converter 62 Matrix circuit 63 Low-pass filter (LPF) 64 Subsampler 65 TCI circuit 69 Mixer 70 Multiplex circuit 71 Frame offset subsampler 72 Digital-analog (D / A) Converter 73 Analog-digital (A / D) converter 76 Mixer 77 Inverse TCI circuit 78 Inverse matrix circuit 79 Digital-analog (D / A) converter 81 _R , 81 _B , 82 _R , 82 _B Field memory 83 _R , 83 _B vertical direction filter 84 frame interpolation circuit 85 _R , 85 _B , 86 _R , 86 _B field memory 87 _R , 87 _B vertical direction filter 88 interpolation interpolation filter 91 analog / digital (A / D) converter 92 Horizontal low pass filter (LPF) 93 Pulling frequency conversion circuit 94 Vertical low-pass filter (LPF) 95 Sub-sampling circuit 96 Horizontal low-pass filter (LPF) 97 Sub-sampling circuit 98 Digital-analog (D / A) converter 99 Analog-digital (A / D) Converter 100 Inter-field interpolation circuit 101 Field memory 102 Horizontal low-pass filter (LPF) 103 Sub-sampling circuit 104 Vertical low-pass filter 105 Sampling frequency conversion circuit 106 Horizontal low-pass filter (LPF) 107 Digital-to-analog (D / A) converter

Front page continuation (72) Koichi Yamaguchi 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside Broadcasting Research Laboratories, Japan Broadcasting Corporation (56) Reference JP-A-60-86994 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04N 11/00-11/22 H04N ^7/ 00-7/68

Claims (2)

(57) [Claims] 1. An offset between lines or frames that makes a cycle of two frames in at least a luminance signal component of a wideband color image signal subjected to primitive sampling.
In a wideband color image signal transmitting apparatus for transmitting the wideband color image signal that has been band-compressed by performing offset subsampling according to a sample pattern, the apparatus is characterized in that an offset subfield between fields is applied to an image signal of a moving image. A field offset subsampler for performing sampling and a color difference signal vertical frequency band limiting circuit block connected to the input side of the field offset subsampler, wherein the color difference signal vertical frequency band limiting circuit block is connected in series. Two connected field memories, a switcher for switching and outputting each input / output of the field memory at a field cycle, and an input / output signal of the field memory switched by the switcher is input to offset between the fields.・ With subsampling A vertical frequency band limiting filter for reducing aliasing distortion of a color difference signal generated in a reconstructed image, and a color difference signal vertical frequency band limiting circuit block provided in each processing system of two types of color difference signals. Broadband color image signal transmission device. 2. A wide band color image for receiving the band-compressed wide band color image signal transmitted from the wide band color image signal transmitting device according to claim 1 and reconstructing a wide band color image signal before band compression. In the signal receiving device, the device is a circuit block for vertical-direction interpolation interpolation of color difference signals for interpolating sample values between fields for each of two types of color difference signals for an image signal of a moving image. The color difference signal vertical interpolation circuit block includes two field memories connected in cascade and at least the band limitation and the sample value of the two kinds of color difference signals in a frame unit composed of odd and even fields. Switching that outputs and switches each field memory input / output in correspondence with the transmission / reception so that the interpolation interpolation signal processing is completed And a vertical interpolation filter for inputting the input / output signals of the field memory switched by the switcher and performing interpolation of sample values between the fields, respectively, processing the two types of color difference signals. A wide-band color image signal receiving device, which is a circuit block for color-difference signal vertical-direction interpolation interpolation provided in a system.