JPH07112271B2 - Time-compression multiplex subsample transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a time compression multiplex sub-sample transmission system for narrowing and transmitting a wideband image signal of a high-definition television or the like, and particularly to a narrowband of the image signal. Improvement of image quality deterioration of moving images by time compression, which is a drawback of the multiple sub-sampling transmission system that enables narrow band transmission of high-definition television wideband image signals by combining various narrow band transmission systems suitable for transmission It is something that is done.

(Prior Art) This kind of multiplex sub-sampled image signal transmission system is disclosed in Japanese Patent Application No. 58-1941 in order to enable wide band high-definition television image signals to be transmitted in a narrow band in satellite broadcasting.
As disclosed in the specification No. 15, it covers various image signal narrow band transmission techniques, and time-division-multiplexes the luminance signal and the color signal in the wideband color image signal of a high-definition television with time axis compression. In addition, while performing sub-sampling for each multiple field period to convert to a narrow band image signal of dot interlace, for an image of a moving part that particularly requires information regarding image change,
Information indicating the motion of an image is multiplexed and transmitted together with a narrow band image signal, and when a wide band high-definition television image signal is restored from the received narrow band image signal, an interpolation period according to the motion information of the image is applied. The image quality of a moving image can be maintained.

(Problems to be Solved by the Invention) However, an image signal of a sample point which is not transmitted by being excluded by the subsample in the image signal subjected to the subsample and dot-interlaced as described above is interpolated at the time of reception. Even if supplemented by interpolation,
Since the interpolation period supplements the missing sample values estimated from the preceding and following subsample values, an error is likely to occur with the true missing sample value, and the larger the amount of motion of the image, the greater the error. It is easy to become. Therefore, the larger the amount of movement is, the more blurred the moving image is and the image quality is deteriorated.
Such deterioration of the image quality of motion is unavoidable as long as the missing sample value by the sub-sample is supplemented by interpolation, and in order to sufficiently prevent the deterioration of the motion image quality, the deterioration of the motion image quality of the moving part of the image is performed. The problem that the conventional multi-subsample image signal transmission method of this kind needs to be solved is that it must transmit true sample values of sufficient density to prevent it.

(Means for Solving Problems) In order to solve the above-mentioned problems in the conventional multiplex sub-sample transmission system, the time compression multiplex sub-sample transmission system of the present invention includes time-axis compression, time division multiplexing and sub-multiplexing for a wideband image signal. Narrow-band image signals that are sampled for narrow-band transmission are further time-compressed to provide periodic blank periods, and the missing sample values generated in the moving parts of the image due to sub-sampling The sampled wideband image signal is time-division multiplexed with the luminance signal and color signal of the wideband image signal and time-division-multiplexed. The band image signal is transmitted together with the motion information signal corresponding to the amount of motion of the image represented by the wide band image signal, and the band image signal is forwarded according to the received motion information signal. In the time compression multiplex sub-sampling transmission system, in which an image signal obtained by subjecting a narrow band image signal to interpolation is separated into a luminance signal and a chrominance signal and each time axis is expanded to restore the wide band image signal, the time axis is The luminance signal in the narrowband image signal formed by performing the compression and the time division multiplexing is further time-axis compressed to a ratio of (n-1) / n for a positive integer n for each transmission period of the luminance signal. Together with the 1 / n transmission period length blank period formed by the time axis compression, the sample value of the luminance signal in the wideband image signal excluded by sub-sampling, the image signal generated by the movement of the image or the interpolation interpolation In addition to supplementary transmission by the number corresponding to the amount of distortion of,
Among a plurality of sections into which the image represented by the wideband image signal is subdivided, a control signal indicating a section corresponding to the sample value is multiplexed and transmitted during a vertical blanking period of the narrowband image signal. It is a thing.

(Operation) Therefore, in the transmission method of the present invention, since the narrow band image signal for transmission is subjected to time-axis compression to widen the band, the amount of information that can be transmitted in the same bandwidth is reduced, and a still image may be somewhat However, the degradation of the image quality of the moving part, which was the most problematic for the high-definition television image signal transmitted and restored by the conventional multiplex sub-sampling method, is caused by the supplementary transmission of the missing sample value. Therefore, according to the transmission method of the present invention, the overall image quality of the restored wideband image signal by the conventional multiplex sub-sampling transmission method can be improved, which is a remarkable effect.

In the transmission method of the present invention, as will be described later, since the control signal for instructing the mode of supplementary sample value supplementary transmission is multiplexed for each of the subdivisions of the screen, the configuration of the transmission system becomes complicated accordingly. However, the improvement of the overall image quality of the restored image is more than a supplement to this drawback.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

First, in order to facilitate understanding of the structure and operation of the transmission system of the present invention, an example of the arrangement of image signals in one horizontal scanning period according to the time compression multiplex subsample transmission system of the present invention and the conventional multiplex subsample transmission. The arrangement of image signals according to the method is shown in comparison with FIGS. 1 (a) and 1 (b), respectively.

In the conventional multiple sub-sample transmission system, as shown in FIG. 1 (b), a narrow band chrominance signal formed by subjecting a color signal component and a luminance signal component of a wide band color image signal to appropriate time axis compression respectively. C and the narrow band luminance signal Y are time-division-multiplexed for each period of one horizontal scanning period (1H), and the time-division multiplexed image signal is further subjected to sub-samples for every plural periods to form a transmission narrow-band image signal. is doing.

On the other hand, in the time compression multiplex sub-sample transmission system of the present invention, as is clear from comparison between FIG. 1 (a) and FIG. 1 (b), the configuration arrangement is exactly the same as in the conventional multiplex sub-sample system. Only the narrow band luminance signal Y in the transmitted narrow band image signal, for example, 4/5
Time-axis compression is further performed at the ratio of
A blank period having a time width of ⅕ is provided between and, and in the blank period, a supplementary signal F for supplementarily transmitting the missing sample value of the motion image excluded by the sub-sample is multiplexed and transmitted.

As the replenishment signal F, the missing sample values in the moving part of the image may be replenished and transmitted according to the amount of movement of the image, and only the slow motion of a small part of the image may be transmitted. In this case, since sufficient high image quality of the moving image can be maintained only by the conventional interpolation, it is possible to prevent supplementary transmission of the missing sample value. Therefore, according to the supplementary transmission of the missing sample values in this manner, the transmission method of the present invention makes it possible to easily maintain the high image quality of the motion image regardless of the motion amount.

Therefore, in the transmission method of the present invention, it is the lack of the sample value of the luminance signal that influences the resolution of the image that causes the deterioration of the image quality due to the lack of the sample value of the moving image. The supplemental transmission of the missing luminance sample value is performed in the blank period of 1/5, which is provided by performing the time axis compression of the ratio of 4/5, and as a result, the resolution of the still image is slightly lower than that described above. . The degree of the resolution degradation is illustrated in FIG. 2 by the change of the customs resolution characteristic when the time base compression ratio is 4/5. As is clear from the figure, the horizontal spatial frequency (MHz) and the vertical spatial frequency (the number of televisions), which represent the horizontal and vertical resolutions in a fixed transmission bandwidth, respectively, are in a linear relationship inversely proportional to each other. The hatched shaded area shown in the drawing sandwiched between the linear resolution characteristic curves in the invention system represents the amount of reduction in resolution due to the time axis compression applied to the luminance signal, and as described above, the transmission system of the invention. From the viewpoint of the overall image quality, the improvement in the image quality of the moving image by means of the above is more than sufficient to compensate for this decrease in resolution.

Further, as described above, in which part on the screen the missing sample value is to be complementarily transmitted as the missing sample value of the moving image to be complementarily transmitted in the blank period provided by the time compression of the transmission narrow band luminance signal Y, It is necessary to specify on the transmitting side according to the movement of the image and transmit the specified information to the receiving side to facilitate signal processing at the time of restoring the wideband image signal.

Therefore, in the transmission method of the present invention, a screen is subdivided to set a large number of sections, and a designation information signal indicating whether or not supplementary transmission of a missing sample value has been performed for each section is displayed in a vertical blanking period. Multiplex transmission is performed collectively for each item.

On the other hand, regarding the signal processing such as signal division for restoring a wideband image signal from the transmission narrowband signal on the receiving side, time-axis expansion, and interpolation, the transmission method of the present invention is basically the same as the conventional multiplex sub-system. It is the same as the sample transmission method, but for the section on the screen where the missing sample value is replenished and transmitted from the transmitting side, the section where the missing sample value is not replenished and transmitted is the same as the conventional transmission method. The sample values estimated by interpolation are not used, but the true sample values replenished and transmitted from the transmitting side are used, and the image, especially,
Depending on the conventional interpolation period, the motion, which has deteriorated the image quality, is accurately restored and reproduced.

Next, a configuration example of the transmission side circuit device and the reception side circuit device in the transmission system of the present invention which performs the above-described image signal processing will be described with reference to FIGS. 3 and 4, respectively.

First, in the configuration example of the transmitting side circuit device shown in FIG. 3, the wideband color image signal from the input terminal T1 is converted into an analog signal.
It is led to a digital converter T2, converted into a digital image signal by a clock signal of, for example, 64.8 MHz, and the digital image signal is led to a time axis compression multiplexing (TCI) circuit T3, and the conventional system shown in FIG. 1 (b). A time-axis compression multiplexing (TCI) signal Ta having the same configuration and arrangement is formed, and the TCI signal Ta is supplied to the still image system T4 and the moving image system T7 in parallel.

In the still image system T4, the TCI signal Ta is sequentially guided to the inter-field pre-filter T5 and the sub-sampling circuit T6, and the spatio-temporal frequency domain in which aliasing distortion is generated by sub-sampling is removed in advance. Sub-sampling is performed at 1/2 rate to form the transmission narrow band still image signal Tb, which is similar to the conventional transmission method. Also in the moving image system T7, the TCI signal Ta is sequentially guided to the intra-field pre-filter T8 and the sub-sampling circuit T10, and after removing the spatio-temporal frequency domain in which the aliasing distortion occurs due to the sub-sampling in advance, for example, as described above. Subsampling is performed at the same 1/2 rate to form the transmission narrowband moving image signal Tc, which is similar to the conventional transmission method.

However, in the transmission method of the present invention, as the intra-field image data for the motion image portion, for example, 4
Of the missing sample values excluded by the inter-frame sub-samples that make a cycle for each field period, about 1/4 of the missing true samples corresponding to, for example, 4/5 of the time compression ratio described above. In-field prefilter T9 and the above-mentioned same rate for pre-removing the spatio-temporal frequency domain that causes aliasing distortion by such anti-phase sub-samples in preparation for the same-rate, anti-phase sub-samples for supplementary transmission of values. , An additional signal processing system including a sub-sampling circuit T11 for performing sub-phase sub-sampling is added to the moving image system T7.
It is disposed inside to form an additional transmission narrow band moving image signal Td having a complementary relationship with the transmission narrow band moving image signal Tc.

As described above, the two complementary narrow-band moving image signals for transmission are supplied to the switching circuit T12, and as described later, the sample values of the moving image portion to be transmitted are those of the original multi-subsample transmission system. In accordance with the result of determining whether or not to perform supplementary transmission according to the present invention, the transmission is appropriately switched to form a comprehensive transmission narrow-band moving image signal Te, which is guided to the linear mixing circuit T13 to generate an image to be described later. In accordance with the result of the motion detection, the transmission narrowband image signal Tf is linearly mixed with the above-mentioned transmission narrowband still image signal Tb under appropriate weighting as in the conventional transmission method.

Then, the transmission narrow band image signal Tf is guided to the inter-frame sub-sampling circuit T14, and at the same time as in the conventional transmission method, for example, the inter-frame offset sub-sampling is performed at the 1/4 rate of the clock signal described above, and the According to the invention, in preparation for time axis compression applied only to the luminance signal for transmission,
The narrow band luminance signal Th subjected to the inter-frame offset sub-sampling is taken out separately from the narrow band chrominance signal Tg. The narrow band chrominance signal Tg extracted from the inter-frame sub-sampling circuit T14 is fed to an adder T19 via a delay circuit T15 which gives a phase delay for matching timing with a phase delay due to signal processing of a narrow band luminance signal described later. Lead. On the other hand, similarly, the narrow band luminance signal T extracted from the inter-frame sub-sampling circuit T14
h is led to the rate conversion circuit T16, for example, the data rate according to the time base compression of the ratio of 4/5, the 1/4 rate of the clock signal of 64.8 MHz and the 4/5 of 16.2 MHz About 13 MH
After converting to z, it is supplied to the adding circuit T17. The adder circuit T17 is provided with the sub-sampling circuit of the true luminance signal lacking sample value to be supplementarily transmitted in the blank period provided by the present invention.
Extracted from T10 and sequentially supplied to the inter-frame sub-sampling circuit T25 and rate conversion circuit T26, and the narrow band luminance signal T
The supplementary luminance signal Ti for exactly the same rate as that applied to h and the reverse phase inter-frame offset sub-samples and the rate conversion of the same rate are sequentially performed, and the signal processing is performed to align the phase with the narrowband luminance signal Th. Is controlled according to the result of supplementary transmission period detection described later.
The narrow band luminance signal Th and the supplementary transmission luminance signal Ti are time-division-multiplexed through the blank period following the transmission period of the narrow band luminance signal Th via T27. Then, the time-division multiplexed luminance signal Tj is guided to the time compression circuit T18, for example, 4/5.
1 time-division multiplexed with the narrowband chrominance signal Tg by time-multiplexing the narrowband chrominance signal Tg into a time-division multiplexed luminance signal Tk having the same rate as that of the narrowband chrominance signal Tg. A narrow band image signal Tl for transmission is formed by the method of the present invention as shown in FIG.

On the other hand, the TCI signal Ta from the time axis compression multiplexing (TCI) circuit T3 is led to the motion detection circuit T23 similar to that in the conventional transmission system, and the motion detection signal resulting from the motion detection of the image is used to stop the linear mixing circuit T13. While controlling the weighted mixing of the image signal and the moving image signal, the motion detection signal is guided to the supplemental portion detection circuit T24, and the missing sample value of the moving image is determined according to the size of the missing sample value of the moving image. Forming an instruction signal Tm indicating a section on the screen to be replenished and transmitted, while controlling the moving image signal switching circuit T12 and on / off switch T27, guide the instruction signal to the addition circuit T20, the narrow band image signal for transmission Tl Time division multiplexing is performed during the vertical blanking period. The time division multiplex transmission signal is guided to a modulator (not shown) via a digital / analog conversion circuit T21 and a transmission line matching filter T22, and a carrier wave is modulated and transmitted.

In the above circuit configuration, the order of signal processing can be appropriately changed as long as the transmission signal according to the present invention having the configuration shown in FIG. 1 (a) is formed.

Next, in the configuration example of the receiving side circuit device shown in FIG. 4, the above-mentioned time division multiplex transmission signal from the input terminal R1 is guided to the analog / digital conversion circuit R2 and is again digital signal Ra.
And supplies it to the multiplex data division circuit R3 to separate the time-division-multiplexed narrowband color signal Rb, narrowband luminance signal Rc, and supplementary luminance signal Rd. The narrow band luminance signal Rc is guided to the time expansion circuit R5, its time axis 5/4 is expanded at a ratio, the narrow band chrominance signal Rb and the adder circuit R7 whose timings are matched are added via the delay circuit R4, and then added again. After setting the time division multiplex state, the inter-frame interpolation circuit R of the still image system
8. It is the same as in the conventional transmission system except that it is supplied in parallel to the supplementary data interpolating circuit R9, the field interpolating circuit R10 and the motion detecting circuit R19 of the moving image system, and the supplementary data interpolating circuit R9 is excluded.

In the inter-frame interpolation circuit R8 of the still image system, inter-frame interpolation is performed on the time division multiplexed still image signal as in the conventional transmission method. Further, in the supplementary data interpolation circuit R9 of the moving image system, the supplemental luminance signal Rd obtained by subjecting the time-division multiplex moving image signal to time axis extension at a ratio of 5/4 by the time extension circuit R6 is converted into an analog / digital conversion circuit. The replenishment partial signal detection circuit R17 supplied with the digital signal Ra from R2 mixes under the control of the replenishment control signal formed by introducing the replenishment section instruction signal detected from the vertical blanking period to the replenishment control circuit R18. The moving image supplement data signal Rf in which the sample value of the moving image is sufficiently supplemented is supplied to the inter-field interpolation circuit R10 to perform inter-field interpolation similar to that in the conventional transmission method.

As described above, the still image signal Re and the moving image signal Rg, which have been widened by inter-frame interpolation and inter-field interpolation, are supplied to the mixing circuit R11, and the time division multiplexed signal is supplied to the conventional transmission system. Under the control of the motion detection signal Rh from the motion detection circuit R19 that performs the same motion detection as described above, the reproduced image signal Ri, which is appropriately mixed according to the motion of the image and subjected to such motion correction, is inserted into the field interpolation circuit. Lead to R12, perform field interpolation similar to that in the conventional transmission system, then supply to color signal decoding circuit R13, decode carrier color signal and extract wideband color difference signal C _W and narrow band color difference signal C _N and digital / analog conversion circuit R1
The wide band luminance signal Y extracted from the field interpolating circuit R12 is output from the output terminals R20 and R21 via 4 and R15 and the output terminal R via the digital-analog conversion circuit R22.
It is taken out from 22 and supplied to an inverse matrix circuit (not shown) to restore the broadband three primary color image signals R, G, B.

(Effects of the Invention) As is apparent from the above description, according to the present invention, for example, a conventional multiple sub-sample developed so that a wide band color image signal of a high definition television or the like can be transmitted in a narrow band in satellite broadcasting or the like. It is possible to reproduce a wideband color image signal with a high quality overall image quality by almost completely eliminating the image blur in the moving part, which was the single biggest drawback in the past, without substantially impairing the basic properties that are the advantage of the transmission method. A special effect is obtained.

In the time compression multiplex sub-sample transmission method of the present invention, the image information to be replenished and transmitted in the blank period provided by time compression of the luminance signal is only auxiliary, and in particular, the replenishment section instruction signal for replenishment transmission control is transmitted. If an unexpected or unavoidable failure occurs, such as when an error occurs,
If there is a possibility that an error may occur in the supplementary image information transmission due to the conventional error detection for the transmission of those control signals, the adoption of supplementary image information is discontinued at any time to cause such image information supplementary transmission. It is preferable to avoid the undesired deterioration of the image quality and maintain at least the high image quality obtained by the conventional multiple sub-sample transmission method.

[Brief description of drawings]

1 (a) and 1 (b) are diagrams showing examples of the configuration and arrangement of multiple sub-sampled image signals by the transmission method of the present invention and the conventional transmission method, respectively, and FIG. 2 is the transmission method of the present invention and the conventional transmission method. 3 and 4 are characteristic curve diagrams showing the spatial resolution characteristics of the transmission image signal in contrast with each other, and FIGS. 3 and 4 are block diagrams respectively showing configuration examples of the circuit device on the transmission side and the circuit device on the reception side in the transmission system of the present invention. is there. T1 …… Input end T2 …… Analog-digital conversion circuit T3 …… Time axis compression multiplexing (TCI) circuit T4 …… Still image system T5 …… Inter-field prefilter T6 …… Sub sample circuit, T7 …… Moving image system T8 …… Pre-filter in field T9 …… Pre-filter in field T10 …… Sub-sample circuit T11 …… Sub-sample circuit T12 …… Switching circuit, T13 …… Linear mixing circuit T14 …… Inter-frame sub-sample circuit T15 …… Delay circuit, T16 …… Rate conversion circuit T17 …… Addition circuit, T18 …… Time compression circuit T19 …… Addition circuit, T20 …… Addition circuit T21 …… Digital-analog conversion circuit T22 …… Transmission line filter, T23 …… Motion detection circuit T24 ...... Replenishment part detection circuit T25 …… Inter-frame sub-sampling circuit T26 …… Rate conversion circuit, T27 …… ON / OFF switch R1 …… Input end R2 …… Analog / digital conversion circuit R3 …… Multiplexed data Splitter circuit R4 ...... Delay circuit, R5 ...... Time expansion circuit R6 ...... Time expansion circuit R7 ...... Supplementary partial signal detection circuit R8 ...... Interframe interpolation circuit R9 ...... Supplementary data interpolation circuit R10 ...... Within field Insertion circuit R11 …… Mixing circuit, R12 …… Field interpolation circuit R13 …… Color signal decoding circuit R14 …… Digital / analog conversion circuit R15 …… Digital / analog conversion circuit R16 …… Digital / analog conversion circuit R17 …… Replenishment Partial signal detection circuit R18 …… Replenishment control circuit R19 …… Motion detection circuit, R20 …… Output end R21 …… Output end, R22 …… Output end

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Izumi 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the broadcasting technology research institute of the Japan Broadcasting Corporation (72) Seiichi Koshi 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 in the Institute of Broadcasting Technology, Japan Broadcasting Corporation (56) References Japanese Patent Laid-Open No. 60-86994 (JP, A) Technical Report of the Television Society ICS 67-7 (59.4.5)

Claims (2)

[Claims] 1. A wideband image signal is a narrowband image signal formed by subjecting a sampled luminance signal and chrominance signal of a wideband image signal to time-axis compression and time-division multiplexing, and sub-sampling every predetermined plurality of fields. Is transmitted together with a motion information signal corresponding to the motion amount of the image represented by, and an image signal obtained by subjecting the narrow band image signal to interpolation interpolation according to the received motion information signal is separated into a luminance signal and a color signal. In the time compression multiplex sub-sample transmission system for expanding the time-base image signal to restore the wideband image signal,
The luminance signal in the narrow-band image signal formed by performing the time-axis compression and the time division multiplexing is further time-divided for a ratio of (n-1) / n for each positive integer n for each transmission period of the luminance signal. Along with axial compression, in the blank period of 1 / n transmission period length formed by the time-axis compression, the sample value of the luminance signal in the wideband image signal excluded by sub-sampling is calculated by the motion of the image or the interpolation. Replenishment transmission is performed by the number corresponding to the magnitude of the generated image signal distortion, and a control signal indicating a section corresponding to the sample value among a plurality of sections into which the image represented by the wideband image signal is subdivided is supplied to the narrowband image. A time compression multiplex sub-sample transmission method characterized in that multiplex transmission is performed during a vertical blanking period of a signal. 2. The transmission system according to claim 1, wherein the control signal is composed of an error detection code, and when an error of the error detection code is detected, the interpolation is performed on the narrow band image signal. A time-compression multiplex subsample transmission method characterized in that it is not applied.