JPH0544237B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-definition/standard television conversion system that allows conversion from a high-definition television system to a current standard television system using a simple device.

Conventionally, in order to facilitate format conversion between high-definition television and standard television, it has been desirable to have a system in which the number of scanning lines of the high-definition television format is an integral multiple of the number of scanning lines of the standard television format. It was considered a thing. Therefore, when conditions for easy conversion are required, the number of scanning lines for high definition television systems has been dependent on that for standard television systems. However, the standards for two-dimensional image information required for high-definition television, such as the number of scanning lines, number of pixels, aspect ratio, etc., should originally be set from a different perspective than the standards for standard television. Under such severe dependent conditions, it becomes difficult to set an optimal high-definition television standard. However, certain dependent conditions are required to enable easy conversion to the standard format.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-quality image that satisfies certain dependent conditions with respect to the standard format in terms of the number of scanning lines and the number of frames, while maintaining the conditions necessary for transmitting and displaying high-quality two-dimensional image information. To provide a high-definition/standard television conversion system that allows easy conversion of high-definition television to a standard system.

In order to achieve such an object, the present invention provides a line selection circuit that selects substantially one line every m lines (m is a positive integer of 2 or more) for a television image signal based on a high-definition television system. and an image signal processing circuit comprising at least a line time expansion circuit for expanding the signal of the selected line to at least m line times; and a synchronizing signal processing circuit for generating a synchronizing signal and adding the synchronizing signal to the signal converted by the image signal processing circuit, the television according to the above-mentioned high-definition television system in which the number of scanning lines is not an integral multiple of each other. In a high-definition/standard television conversion method for converting a digital image signal into a television image signal of a standard television system, the television image signal according to the high-definition television system is converted into a television image signal according to the high-definition television system. When the number of scanning lines is n _H and the frame frequency is _PH , and the number of scanning lines of the television image signal according to the standard television system is n _S and the frame frequency is _PS , then n _H・_PH = m・n _S・It is characterized by being a television image signal expressed by the relationship _PS (here, _PH ≠ _PS because the number of scanning lines is not an integral multiple of each other).

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows the signal standard of the high-definition television system according to the present invention in comparison with the signal waveform of the standard television system. First, in a high-definition television system, the amount of information, the number of scanning lines, and the number of pixels of a two-dimensional image are determined depending on the purpose of use. For example, when viewing a television from a distance 2.5 times the screen height, the required number of scanning lines is approximately 1480, and when viewing from a distance 3 times the screen height, the required number of scanning lines is approximately 1125. It is known from research by the present inventors that this is necessary.

For this reason, for such a high-definition television system with a predetermined number of scanning lines, the present invention does not set the number of scanning lines dependently on the number of scanning lines of the standard television system as in the past. The field frequency and frame frequency are selected so that the horizontal scanning frequency of the high-definition television system is an integral multiple of the horizontal scanning frequency of the standard television system. In other words, if the number of scanning lines of the standard television system is n _S , the frame frequency is _PS , the required number of scanning lines of the high-definition television system is n _H , and the frame frequency is _PH , then the following equation (1) is obtained. can get.

n _H・_PH = m・n _S・_PS (1) However, m is a positive integer that is 2 or more and under the condition that _PH does not change more than _PS .

For example, in a system where the viewing distance is 2.5 times the screen height as described above, n _H = 1480 lines, m = 3, _PH = 525 lines x 30 frames x 3/1480 = 31.9257Hz, In a system with n _H = 1125 lines when the viewing distance is tripled, m = 2, and _PH = 28.0 Hz.

This way _{the PH} is close to _PS (30Hz), for example 28~
Assuming 32Hz, when m=2, approximately 984<n _H
1125, and when m = 3, it is approximately 1476 < n _H < 1688
Therefore, the degree of freedom in selecting n _H increases.

Figures 1A and 1B show a comparison of line signals between these high-definition television systems (abbreviated as HDTV) and standard television systems (abbreviated as STD-TV) when m = 3; Similarly, C and D indicate the relationship of frame signals between the two.

Here, since the horizontal scanning period of HDTV and STD-TV has a simple proportional relationship of 1:3, for example, as shown in Figure 2, from the HDTV signal to the STD-TV
The conversion to can be performed very easily using a simple line memory that can be written to and read from. That is, one line out of every three lines of the HDTV signal shown in Fig. 1B is extracted by a switcher as shown in Fig. 2A, the output of this switcher is written into a digital line memory, and the line time is expanded as shown in Fig. 2B. The signal is read slowly through the circuit in three times the time to extract the signal corresponding to FIG. 1A.

Generally, the aspect ratio of HDTV is STD−TV
In this case, taking into account that the aspect ratio is longer than that in the case of 3:5, for example, the HDTV signal of the part corresponding to the aspect ratio of STD-TV from among the written HDTV signals as shown in Figure 3A is lined up. A time expansion circuit reads out the STD-TV over the entire horizontal scanning period, thereby creating a line signal having the required STD-TV aspect ratio expanded in time as shown in FIG. 3B.

FIG. 4 is an example of a configuration showing the above-mentioned system conversion including a synchronization signal conversion processing circuit system. Here, the HDTV signal is supplied from the terminal T1 to the synchronization separation circuit 1 to separate the synchronization signal and the video signal. The separated video signal components are supplied to an A/D converter 2 to obtain an encoded HDTV signal. Regarding this HDTV signal, as mentioned above, m pieces of data are transmitted per line period of the STD-TV signal.
HDTV signal line signals are assigned.
Therefore, in switcher 3, A/D converter 2
The HDTV signals are extracted one by one from m and transferred to the line memory 4. This line memory 4
is a writable and readable memory,
The input signal to the write terminal T2, that is, the one-line signal of the HDTV signal with aspect correction to be displayed during the horizontal scanning period of the STD-TV signal shown in FIG. 2A or FIG. 3A is written. Further, at the read terminal T3 of the memory 4, this written signal is time-expanded to one line period of the STD-TV signal and read out. The read output signal is
The signal is supplied to the A converter 5 and converted into an analog signal. Supply this analog signal to the synchronization adder 6,
Information necessary for horizontal and vertical synchronization obtained as described later is added and output as an output signal from terminal T6.

In the figure, 7 is a pulse generator that generates pulses at a frequency twice or three times that of the HDTV signal according to the value of m mentioned above, and the horizontal scanning frequency of the HDTV signal.
For _HH , it is an _m.HH pulse generator. This pulse generator 7 is supplied with the synchronization signal taken out from the synchronization separation circuit 1 to adjust the phase of the oscillation pulse.
Synchronize with the _HH phase of the HDTV signal. 8 is a vertical synchronization position separation circuit which extracts the vertical synchronization pulse of the HDTV signal from the synchronization signal taken out from the synchronization separation circuit 1, and applies this vertical synchronization pulse to the counter circuit 9 as a reset pulse. This counter circuit 9 counts down the output from the pulse generator 7 by an appropriate value to generate a vertical synchronizing signal. This vertical synchronization signal is supplied to the synchronization adder 6 and added to the conversion signal from the D/A converter 5. In addition, the output signal from the pulse generator 7 is transferred to the 1/2m counter circuit 1.
It counts down at 0 and supplies it to the synchronization adder 6 as a horizontal synchronization signal of the conversion signal from the D/A converter 5.

Here, the counter circuit 9 and its output signal will be explained in more detail using a system where m=2 as an example. Figures 5A to 5D show n _H =
This figure shows a television raster pattern of the present invention method with m=2 and _PH =28.0 for 1125 HDTVs. In this case, the pulse generator 7 shown in FIG.
Generates 2 _HH . Figure 5 A shows n _H = 1125 pieces.
An HDTV raster is shown, and FIGS. 5B, C, and D show raster patterns obtained by performing various types of vertical synchronization signal processing on signals converted to STD-TV. First, in FIG. 5B, the HDTV vertical synchronizing signal obtained every n _H =1125 as the output of the counter circuit 9 is added directly to the conversion signal, and scanning returns to the original signal at the fifth field. This is shown in waveforms as shown in FIG. 6C. Here, FRM is a frame pulse and FLD is a field pulse.
However, the horizontal synchronization signal is omitted. In this case, there is a drawback that correct interlaced scanning images cannot be obtained within odd and even fields. next,
As shown in FIG. 6D, the counter circuit 9 counts from n _H +1=1126 in the first field, and n _H − in the second field constituting one frame.
1 = 1124 counts. The raster pattern obtained in this case is as shown in FIG. 5C, which is a correct interlaced pattern in terms of scanning. Therefore, the line structure of the image displayed by the converted signal is easier to see in FIG. 5C than in FIG. 5B. However, in FIG. 5C, the scan lines 563, 56 shown in the figure
As you can see from the information in 5,567 compared to Figure 5A, the image will be played back with a shift of one scanning line on the HDTV, so the image content will not be displayed correctly on the screen. The resolution in the vertical direction deteriorates.

FIG. 5D shows a generated converted signal that further improves this defect. Regarding the original HDTV signal, the signal of one field of the frame, for example, the latter field, is the average value (n+
Create a signal of n ₊₁ )/2, that is, a linear interpolation signal,
Vertical synchronization information similar to that shown in FIG. 5C is added to this signal to obtain a converted signal. FIG. 5D shows the raster pattern in this case, and the quality of the reproduced image in this case is improved compared to the case in FIG. 5C.

Here, FIG. 7 shows an example of a circuit arrangement for carrying out the scanning form that allows the raster pattern shown in FIG. 5D to be obtained, and FIG. 6E shows signal waveforms at various parts thereof.

In FIG. 7, the same parts as in FIG. 4 are given the same reference numerals. In this example, the output from the A/D converter 2 is directly or
It is connected to the switcher 3 via a system consisting of a 1H memory, an adder 13, and a 1/2 divider 14. Here, the switch 11 is switched for each field by a vertical synchronization pulse from the vertical synchronization position separation circuit 8. The operation in the fields in which switch 11 is directly connected to switch 3, such as the first field shown in FIGS. 6A-E, is similar to that in FIG. That is, when an HDTV signal having a frame pulse FRM and a field pulse FLD is applied to the input terminal T1 as shown in FIG. Written to the memory of circuit 4. The written signal is delayed by 1H as shown in Figure 6B, and by slowly reading out this written signal from the memory, a time-expanded line signal as shown in Figure 6C is obtained. It will be done. For this line signal train, as shown in FIG. 6D or E, the count value of the counter circuit 9 is calculated for each field as described above _.
1, that is, frame pulse FRM and field pulse FLD obtained by switching to 1126 and 1124.
and horizontal sync pulses are added in the sync adder 6. For the latter field, the switch 11 is switched and the output from the A/D converter 2 is fed through the 1H memory 12 and directly to the adder 13, where it is added and then divided by 1/2. The signal is halved by the converter 14 to obtain a signal with an average value (n+n ₊₁ )/2 between the two lines. This signal is shown in Figure 6E as 564565 and 5665.
67,...etc. The process of adding vertical and horizontal synchronization signals to such linear interpolation signals is the same as that already described above.

In the present invention, as described above, when m=2, the HDTV signal is converted into a signal in the form shown in FIG. 6 C, D or E, and is output from the output terminal T6 shown in FIG. 4 or 7. . The field frequency and frame frequency of the system-converted signal extracted in this way are those of the high-definition television system, so although they are slightly different from the standard television system, the horizontal scanning frequency is that of the standard television system. is converted into the same signal by a simple device such as a one-line memory. In general, television receivers do not operate even if the horizontal scanning frequency fluctuates even slightly, but the vertical scanning frequency is operated using a circuit with a wide response band, so _P , _F
The pulse drive operation is also performed for variations in the field frequency, so that the converted signal obtained by the present invention is capable of reproducing television images on a standard television receiver.

That is, in the present invention, it is possible to determine a high-definition television system based on necessary two-dimensional image information, and to obtain a high-definition television system that can be easily converted into a standard television system.

As is clear from the above, according to the present invention, conversion from a standard television system can be achieved with a simple configuration such as a line memory while maintaining the ability to reproduce two-dimensional image information, which is most necessary for a high-definition television system. Therefore, it is promising as a future television system.

[Brief explanation of the drawing]

1A to 1D are signal waveform diagrams for explaining the scanning standards of the standard television system and high-definition television system, and FIGS. 2A and 2B are signal waveform diagrams for explaining the principle of signal conversion processing in the present invention. , Figure 3A
4 is a block diagram showing an example of a circuit layout implementing the present invention, and FIGS. 5A to 5D show raster patterns in various examples of system conversion signals according to the present invention. 6A to 6E are signal waveform diagrams showing various examples according to the present invention, and FIG. 7 is a block diagram showing another example of a circuit arrangement for implementing the present invention. 1... Synchronous separation circuit, 2... A/D converter, 3
...Switcher, 4...Line memory, 5...D/A converter, 6...Synchronization adder, 7...Pulse generator,
8... Vertical synchronization position separation circuit, 9... Counter circuit,
10...1/2m counter circuit, 11...switch, 1
2...1H memory, 13...adder, 14...1/2 divider.

Claims (1)

[Claims] 1. A line selection circuit that selects substantially one line every m lines (m is a positive integer of 2 or more) for a television image signal based on a high-definition television system, and an image signal processing circuit comprising at least a line time expansion circuit for expanding a line signal to at least m line times; at least a synchronous signal processing circuit that adds a signal to the signal converted by the image signal processing circuit, and standardizes television image signals according to the high-definition television system in which the number of scanning lines is not an integral multiple of each other. In a high-definition/standard television conversion method for converting into a television image signal of a television system, the television image signal of the high-definition television system has a number of scanning lines of the television image signal of the high-definition television system. Let n _H and frame frequency be _PH ,
The number of scanning lines of the television image signal according to the standard television system is _nS and the frame frequency is
When _PS , it is a television image signal expressed by the relationship n _H・_PH = m・n _S・_PS (here, _PH ≠ _PS because the number of scanning lines is not an integral multiple of each other). A high-definition/standard television conversion system featuring