JPH0244985A - Receiver for band compression television signal - Google Patents

Abstract

PURPOSE:To simplify an additional component and to make a receiver small in size by using a frame memory in a temporary filter circuit so as to execute a still picture display function. CONSTITUTION:A 1-frame luminance signal is stored in a frame memory 17 in the temporary filter circuit 16 in the still picture display mode and while the still picture display mode is selected, the stored luminance signal is outputted repetitively. On the other hand, in the still picture display mode, a still picture frame memory section 26 stores the one-frame color signal in the built-in frame memory and while the still display mode is selected, the stored color signal is repetitively outputted. Thus, the same luminance signal and chrominance signal are outputted repetitively and the still display is executed. Then the still picture display function is executed with the addition of simple constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the so-called MUSE (Multipl
e 5ub-nyquist Sampling En
The present invention relates to a receiver for compressed band television signals according to the coding method, and is particularly intended to realize a still display function.

[Prior art] The baseband bandwidth of high-definition television signals is approximately 30
[MHz], which cannot be transmitted using current satellite broadcasting channels, and in order to transmit it, it is necessary to compress the band to approximately 81MHz.

The so-called MUSE system has been proposed as one of the systems for transmitting high-definition television signals with band compression.

This MUSE method uses a band compression method as exemplified below. (1) The time axis of the color signal is compressed to 1/4 and multiplexed into the horizontal blanking period of the luminance signal. (
2) Use dot interlacing with interfield, interframe offset sampling in blue contention areas of the image. (3) Dot interlacing with line-to-line offset is used in the moving region of the image. (4) Motion compensation keeps resolution degradation to a minimum during panning and tilting.

Therefore, in the receiving device, a band expansion configuration compatible with these band compression methods is required.

[Problems to be Solved by the Invention] Recently, television receivers with a static display function have appeared. Therefore, it is desirable that a receiving device that receives MUSE television signals also have a static display function.

However, as described above, the MUSE television signal has a signal format different from that of the so-called NTSC television signal, so existing static display configurations cannot be applied as is.

The present invention has been made in consideration of the above points, and M
It is an object of the present invention to provide a receiver for compressed band television signals that can realize a static display function with a simple configuration for compressed band television signals according to the USE system.

[Means for Solving the Problem] In order to solve the problem, in the present invention, the luminance signal and the color signal are each subjected to dot interlacing in the static area by inter-field and inter-frame offset sampling, In the dynamic area, the band compressed television signal that has been subjected to dot interlacing due to the line-to-line offset 1 is received and demodulated, and the stationary area is installed after the interpolation means for restoring the dot interlacing to the luminance signal. It is equipped with a temporal filter that reduces unnecessary components on the time axis when switching between interpolation processing for the color signal and interpolation processing for the dynamic region, and a line-sequential In a compressed band television signal receiving device equipped with a line sequential decoding circuit that converts a color signal into a color difference signal for each scanning line, when a still image display mode is selected, one frame is stored in the frame memory of the temporal filter circuit. a luminance signal holding means for storing the luminance signal and always outputting the stored luminance signal to the next circuit of the temporal filter circuit; and, in the case of an operation mode other than the still image display mode, the interpolation for the color signal. The color signal from the means is applied as is to the line sequential decoding means, and when the still image display mode is selected, one frame of color signal is stored in the built-in frame memory, and the stored color signal is always used. and a color signal holding means for outputting the color signal.

[Function] When the still image display mode is entered, the luminance signal holding means stores one frame of the luminance signal in the frame memory of the temporal filter circuit, and retains this unstored luminance signal while the still image display mode is selected. is output repeatedly. On the other hand, the color signal holding means stores one frame of color signals in the built-in frame memory when the still image display mode is entered, and repeatedly outputs this stored color signal while the still image display mode is selected. let

In this way, the same luminance signal and color signal are repeatedly output to perform static display.

Note that in modes other than the still image display mode, the luminance signal holding means does not perform any processing, the temporal filter circuit uses frame memory to reduce unnecessary components at the boundary between the still area and the moving area, and the color signal holding means does not perform any processing. , outputs the input color signal as it is to the next stage circuit. That is, these holding means do not affect normal operation.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 1 shows the overall configuration of the receiving device according to this embodiment.
Approximately 8 [
A television signal according to the MUSE system demodulated to the baseband of MH2] is input to this receiving device.

The input television signal is applied to an analog/digital conversion circuit, and this analog/digital conversion circuit]
- is converted into digital data and then applied to the de-emphasis circuit 2. The de-emphasis circuit 2 is
The inverse processing of the processing by the emphasis circuit of the transmission system is performed, and the de-emphasized signal is applied to the motion detection circuit 3, the interframe interpolation circuit 4, and the synchronization separation/timing generation circuit 5.

The motion detection circuit 3 detects motion of the television signal after de-emphasis processing and outputs a motion detection signal to each circuit as described below.

The synchronization separation/timing generation circuit 5 separates a synchronization signal from the de-emphasis-processed television signal, forms and outputs a control signal for controlling the operation timing of each circuit, which will be described later.

The interframe interpolation circuit 4 uses a frame memory 6 to compress the static region of the received television signal, which is subjected to dot interlacing by interframe offset sampling, and uses the frame memory 6 as data for the dots that have no data. Interpolate with previous data.

At this time, data of one frame before is moved in a predetermined direction based on a motion detection signal given from the motion detection circuit 3, and interpolated so as to prevent deterioration of the resolution of the screen such as panning and tilting I-1. Further, the frame memory 6 is used to perform noise reduction processing.

The television signal output from the inter-frame interpolation circuit 4 is given to a low-pass filter circuit 7 to limit its band, and the sampling frequency is converted by a sampling frequency conversion circuit 8, and the television signal is sent to the next inter-field interpolation circuit. The data is provided to the interfield interpolation circuit 9 in such a way that it can be easily processed by the interfield interpolation circuit 9.

The interfield interpolation circuit 9 uses the field memory 10 to perform interlacing using data from one field before as data for dots with no data, since the static region is interlaced by sampling at the interfield offset 1. Insert.

At this time, the data position is corrected in the horizontal direction according to the motion detection signal given from the motion detection circuit 3, and the panned screen is treated as a still area to prevent resolution deterioration. This inter-field interpolated television signal is given to the adaptive mixing circuit 11-.

The television signal subjected to interframe interpolation by the above-mentioned interframe interpolation circuit 4 is given to the intrafield interpolation circuit 13 via the subsample switch circuit ]-2. The sub-sample switch circuit 12 opens at the data timing of a dot interpolated between frames and replaces the data of that dot with "0", and closes for dot data with data of the original frame and replaces that data. It is something that allows it to pass through. The intra-field interpolation circuit 13 has a memory for several lines, and the field interpolation circuit 13 has a memory for several lines.
is formed by interpolating the data of several dots adjacent in the vertical and horizontal directions.

This is because dot interlacing is applied to the moving region of the image by offset between lines, and cubic interpolation is not possible.

The television signal subjected to field interpolation in this manner is provided to the noise coring 14. The noise coring 14 removes components having a predetermined frequency or higher and whose level is below a predetermined value as noise components, and provides the television signal after noise removal to the above-mentioned adaptive mixing circuit 11.

A motion detection signal is supplied from the motion detection circuit 3 to the adaptive mixing circuit]-1. The adaptive mixing circuit 11- interpolates the television signal interpolated as a still area given from the interfield interpolation circuit 9 and the moving area given from the noise coring 14 at a ratio according to this motion detection signal. The processed television signal is mixed with the processed television signal, and the mixed television signal is provided to the low frequency replacement circuit 1-5.

A television signal is supplied to the low frequency replacement circuit 15 from the de-emphasis circuit 2. The low frequency replacement circuit 15 converts components of 4 [MH2] or less of the television signal given from the adaptive mixing circuit ]-1 to the de-emphasis circuit 2.
4 [formerly 71 and below] components of the television signal given from the above are replaced, and the replaced television signal is given to the temporal filter circuit 1-6.

Here, the low frequency replacement circuit 15 is provided because the 4
[In the region below Hzl, there is no aliasing due to interframe offset sampling, so by replacing it, the vertical frequency characteristics are flattened, and the vertical filters provided in the interpolation circuits 9 and 13 described above are This is to simplify the configuration.

The temporal filter circuit 16 has a detailed configuration shown in FIG. 2, and basically uses the frame memory 1-7 to perform processing to reduce changes in resolution at points of change between a still area and a moving area. do. In addition to this basic processing, this embodiment also provides a static display function as described below.
This is a process that must be carried out to achieve this goal. The television signal from temporal filter circuit 16 is applied to matrix circuit 18.

In the case of a television signal according to the MUSE system, the color 1 word is inserted into the horizontal blanking period, so when display processing is performed on a cathode ray tube (CRT) display device (not shown), the signal in the horizontal blanking period is blank. Therefore, from temporal filter circuit 1-6 to matrix circuit 1
Even if the television signal for 8 includes a chrominance signal, that part is meaningless, and from this point on, the processing system from the global filter circuit 7 to the frame memory 17 constitutes a luminance signal processing system.

The television signal output from the above-mentioned interframe interpolation circuit 4 is given to a time axis expansion circuit 20. The time axis expansion circuit 20 extracts the color signal compressed to 1/4 and inserted into the horizontal blanking period based on the control signal given from the synchronization separation/timing generation circuit 5, and quadruples the color signal. The time axis is expanded and applied to the interfield interpolation circuit 21.

The interfield interpolation circuit 21 uses the field memory 22 to interpolate dots with no data in the data one field before so as to correspond to the dot interlace for the static area. In this case, as in the luminance signal processing system, one image is formed from data between four fields through interframe interpolation and interfield interpolation, so the resolution can be increased. This means that The inter-field interpolated color signal is given to the adaptive mixing port Frf123.

Further, the television signal that has passed through the noise coring 1.4 described above is given to the time axis expansion circuit 24. This time axis expansion circuit extracts the color signal inserted in the horizontal blanking period with the time axis compressed to ]/4 based on the control signal given from the synchronization separation/timing generation circuit 5, and The time axis is expanded four times and applied to the field interpolation circuit 25.

This intra-field interpolation circuit 25 is provided in response to dot interlacing based on line-to-line offset of the color signal for the moving area, and uses built-in memory for several lines to perform vertical and horizontal interpolation. The data of the dot of interest is interpolated from the adjacent dot data, and the interpolated color signal is supplied to the adaptive mixing circuit 26.

The adaptive mixing circuit 26 is given a motion detection signal from the motion detection circuit 3, and the adaptive mixing circuit 26 receives the color signal from the interfield interpolation circuit 21, which has been interpolated between fields in consideration of the static region. and the color signal from the intra-field interpolation circuit 25, which has been interpolated within the field in consideration of the moving area, at a ratio determined according to the motion detection signal, and outputs the mixed signal to the frame memory section 26 for still display.

This still display frame memory section 26 is different from the conventional circuit and is provided in this embodiment.
When the static display mode is not selected, the color signal given from the adaptive mixing circuit 23 is passed sequentially, and when the static display mode is selected, each frame is configured as shown in the figure. The same color signal is output for each color.

The color signal from the still display frame memory unit 26 is transmitted through line 1.
The signal is applied to the warm decoding circuit 27. In the color signal according to the MUSE method, color difference signals R-Y and BY are inserted line-sequentially, and the line-sequential decoding circuit 27 separates and takes out these color difference signals and supplies them to the sampling frequency conversion circuit 28.

The sampling frequency conversion circuit 1i'828 is the matrix circuit 1
The sampling frequency of the incoming color difference signal is converted to the same sampling frequency as the sampling frequency of the luminance signal applied from the temporal filter circuit 16 to the matrix circuit 1-8 so that the conversion processing by 8 can be performed satisfactorily.

The matrix circuit 18 performs matrix processing on the luminance signal provided from the temporal filter circuit 16 and the color difference signal provided from the sampling frequency conversion circuit 28, converting it into three primary color signals, and converts each primary color signal into a corresponding digital/analog signal. It is applied to circuits 29R, 129G and 29B. Each of the digital/analog conversion circuits 29R to 29B converts a primary color signal made of a digital signal into an analog signal and outputs the analog signal to a display device (not shown).

Temporal Filter 0F16 Next, the detailed configuration of the temporal filter circuit 16 will be explained with reference to FIG.

In FIG. 2, the luminance signal subjected to low frequency substitution by the low frequency substitution circuit 15 is applied to a two-dimensional low-pass filter circuit 30, spread two-dimensionally, and applied as a subtraction input to a subtraction circuit 31. The four subtraction circuits 31 include a low frequency replacement circuit 1.
The luminance signal from -5 is given as the input to be subtracted, and the high frequency component of the luminance signal for this temporal filter circuit 16 is extracted by the subtraction process. by the way,
The high-frequency components obtained in this way contain many normal noise components and high-frequency components that occur at the boundary between the still and moving regions because the processing is different between the still and moving regions. . Therefore, past information is used to remove these.

The high frequency component of this luminance signal is given as an input to be subtracted to the subtraction circuit 32, and the subtraction circuit 32 subtracts the delayed signal containing the past history given from the frame memory 17 from the high frequency component of this luminance signal. Then, this subtraction signal is given to the conversion table circuit 33 and the subtraction circuit 34. The conversion table circuit 33 obtains a bell output signal corresponding to the input signal level and supplies it to the subtraction circuit 34. This subtraction circuit 34 is
This converted signal is subtracted from the signal from the subtraction circuit 32.

Here, the conversion of the conversion table circuit 33 is performed by the subtraction circuit 34.
Among the signal components from the subtraction circuit 32, which are outputted from the subtraction circuit 34, the output signal is converted so that components having a predetermined frequency or more and a predetermined level are suppressed to a predetermined level or less.

The output signal from the subtraction circuit 34 is given to the frame memory 17 via a selector circuit 35, which will be described later, and is delayed by one frame via this frame memory 17.
The signal is applied to the above-mentioned subtraction circuit 32 via the coefficient unit 36.

In this way, the cyclic processing is performed to suppress unnecessary high-frequency components at the boundary between the moving area and the static area, and the subtraction circuit 3
The processed high frequency component from 4 is given to the minimum absolute value selection circuit 37 as a first selection input. Here, - noise components may be mixed in, and what passes through the subtraction circuit 34 is not necessarily optimally filtered, and the high-frequency components before passing through the subtraction circuit 34 is also given as the second selection input to the absolute value minimum selection circuit #137, and the average value of the high frequency components before and after passing through the subtraction circuit 34 is sent to the average value circuit 38.
is obtained and given to the minimum absolute value selection circuit 37 as the third selection input.

1.8 The minimum absolute value selection circuit 37 selects the minimum value from among the selection inputs and supplies it to the three adder circuits. The three adder circuits are supplied with the low-frequency components of the luminance signal from the two-dimensional low-pass filter circuit 30, add the processed high-frequency components to return the luminance signal in a predetermined band, and send the selector circuit 40, which will be described later, to the three adder circuits. The signal is outputted to the MARIX circuit 1-9 via the input signal.

In addition to the configuration for realizing the original functions of the temporal filter circuit 1-6, in this embodiment, the temporal filter circuit 16 is provided with a configuration for realizing a still image display function.

The selector circuit 35 described above is of a three-man configuration,
The input terminals are switched according to a control signal given from the synchronization separation/timing generation circuit 5. In modes other than still image display mode, the subtraction output from the subtraction circuit 34 is input.

On the other hand, in the still image display mode, the selector circuit 35 only controls the low frequency replacement circuit 1 during the first frame.
-5 is selected and stored in the frame memory 17 downstream of this selector circuit 35, and during the subsequent still image display mode period, the output signal from frame memory]-7 is selected and stored in the frame memory 17 at the subsequent stage of this selector circuit 35. The switching operation is performed so as to give the

That is, when the still image display mode is entered, a luminance signal for one frame is captured, after which this luminance signal is circulated and stored in the frame memory 17, and the same luminance signal is output from the frame memory 17 for each frame. That's what I do.

The luminance signal output from the frame memory 1-7 is given to the selector circuit 40 described above. This selector circuit 40 switches the input terminal according to a control signal given from the synchronization separation/timing generation circuit 5. In modes other than the still image display mode, the luminance signals from the three adder circuits are selected in a double manner, and in the still image display mode, the luminance signals from the frame memory 1.7 are selected.

Thus, in the still image display mode, the luminance signal once stored in the frame memory 1-7 is applied to each frame via the selector circuit 40 to the matrix circuit 1-8.

Table 6 Frame Memory 26 Next, details of the still display frame memory section 26 will be explained with reference to FIG. 3.

The color signal output from the adaptive mixing circuit 23 is given to a selector circuit 45. The selector circuit 45 has synchronous separation and
The input terminals are switched according to a control signal given from the timing generation circuit 5. In modes other than the still image display mode, the color signal from the adaptive mixing circuit 23 is selected, and in the still image display mode, the color signal from the frame memory 46 provided at the next stage of the selector circuit 45 is selected.

The color signal output from the frame memory 46 is fed back to the selector circuit 45 and is also given to the selector circuit 47 for output. The selector circuit 47 is also directly given the color signal from the selector circuit 45 for input. The selector circuit 47 switches the input terminal according to the control I/roll signal given from the synchronization separation/timing generation circuit 5. In modes other than the still image display mode, the color signal from the selector circuit 2]- path 45 is selected and sent to the line sequential decoding circuit 27.
In the still image display mode, the color signals from the frame memory 46 are selected and sent to the line sequential decoding circuit 27.
Output to.

Here, in the still image display mode, the color signal output from the frame memory 46 is selected by the selector circuit 45 and stored in the frame memory 46, so the color signal output via the output selector circuit 47 is Each frame is the same, making it possible to display a still image.

Therefore, according to the above-described embodiment, a still image display function can be realized even in a receiver for compressed band television signals according to the MUSE method.

In this way, since the frame memory 17 in the temporal filter circuit]-6 is utilized, the added components can be made simpler and smaller than in the case of such additional functions. In addition, regarding color signals, we have inserted a frame memory for still images in the color signal processing part instead of the color difference signal processing part, so only one frame memory is required to realize the still image display function. This also prevents the composition from becoming complicated.

In the above embodiment, in the still image display mode, in order to repeatedly output the same signals from the frame memories 17 and 46, the signals output from the frame memories 17 and 46 are returned to the frame memories ↑7 and 46. Although this is shown, writing to the frame memories 17 and 46 may be stopped and reading may be repeated. In this case, depending on the semiconductor element used in the frame memories 1.7 and 46, writing is stopped and only reading is repeated, so there is a risk that a large amount of noise may be mixed into the output signal as time passes.

can be expressed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the band compression television signal receiving device according to the present invention, FIG. 2 is a block diagram showing the detailed configuration of its temporal filter circuit, and FIG. 3 is its still image frame memory. FIG. 3 is a block diagram showing a detailed configuration of the unit. 16... Temporal filter circuit, 17.46 frame memory, 26... Still image frame memory section, 35
．． 40.45.47...Selector circuit.

Claims (1)

[Claims] A compressed band television signal in which the luminance signal and color signal are subjected to dot interlacing using inter-field and inter-frame offset sampling in the static area, and dot interlacing using inter-line offset sampling in the moving area. which receives and demodulates the
At the subsequent stage of the interpolation means for restoring the dot interlacing for the luminance signal, a temporal filter is provided to reduce unnecessary components on the time axis that occur when switching between interpolation processing for a static region and interpolation processing for a moving region. In a receiver for compressed band television signals, which includes a line-sequential decoding circuit that converts a line-sequential color signal into a color difference signal for each scanning line at the next stage of the interpolation means for restoring dot interlacing in the signal, in a still image display mode. is selected, a luminance signal holding means for storing one frame of luminance signal in the frame memory of the temporal filter circuit and repeatedly outputting the stored luminance signal to the next stage circuit of the temporal filter circuit; In the case of an operation mode other than the image display mode, the color signal from the interpolation means for the color signal is applied as is to the line sequential decoding means, and when the still image display mode is selected, the built-in frame memory 1. A receiver for a compressed band television signal, comprising: color signal holding means for storing one frame of color signals in a frame, and for repeatedly outputting the stored color signals to the line sequential decoding means.