JPS63185291A - Scanning line interpolation circuit - Google Patents

Abstract

PURPOSE:To improve the picture quality of a picture field with a motion by separating an input television signal into the signal with a small temporal change and the signal with the large temporal change, by means of a filter containing a time axis direction, and synthesiz ing the former being interpolated by a customary technology, and the latter being only time- compressed without an interpolation. CONSTITUTION:A difference between the output of a two-dimensional filter 13 and a delayed output is obtained by a difference circuit 30, and at the same time, the output of the filter 13 is added to the temporally low band component of the input signal from a delay circuit 12 by a summation circuit 31. The output of the difference circuit 30 is the temporally and spatially high frequency component of the changing component of the picture field, and is given to a time compression circuit 32. The signal that the temporally and spatially high frequency component is subtracted from the input signal (r) of the output of the summation circuit 31, is interpolated by a customary interlacing scanning-progressive scanning converting interpolation circuit 36. The outputs from the time compression circuit 32 and the interpolation circuit 36 are summed by the summation circuit 51, and come to be the signal (r') which is interpolated by the progressive scanning. Accordingly, the number of scanning lines can be converted without the interpolation of a signal component or the like corresponding to the temporal change of the picture field.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a scanning line interpolation circuit for television images! 0
．． The present invention relates to a scanning line interpolation circuit suitable for converting an interlaced television signal into a progressive scanning television signal.

[Conventional technology]

Conventionally, technology that converts interlaced scanning television signals into progressive scanning as in the current broadcasting system and displays them requires only 1%
As described in 1982-12185, the signals of the scanning lines that are not sent in each field are calculated by averaging the signals of the scanning lines of the previous field or the signals of the scanning lines of the preceding and following fields according to the movement of the screen. It was generated by interpolation by switching and averaging the signals of the upper and lower scanning lines, or by changing the load and averaging.

[Problem that the invention seeks to solve]

In the above conventional technology, in interpolation by averaging the upper and lower scanning lines used when the screen moves, if the scanning line interval between fields and the interval of horizontal stripes on the screen almost match, the screen after interpolation becomes brighter for each field. This resulted in problems with image quality deterioration, such as lower resolution and noticeable flicker.

Therefore, one object of the present invention is to provide a scanning line interpolation circuit that does not cause image quality deterioration such as a reduction in the resolution of moving images or flicker even when interpolating an interlaced scanning television signal and converting it into a progressive scanning television signal. It's about doing.

[Means for solving problems]

The object of the present invention is to divide an input television signal into a signal with little temporal variation and a signal with large temporal variation by using a p-wave filter including the time axis direction, interpolate the former by the conventional technique, and do not interpolate the latter. This is achieved by performing time compression and combining with the interpolated former.

[Effect]

According to the interpolation of the present invention, many of the signal components of screen movement are interlaced on a screen that is sequentially scanned with equal constraints.
Even if there is a movement of small horizontal stripes, it can be resolved, and the image quality of the screen is improved, such as without increasing flicker.

〔Example〕

An embodiment in which the present invention is applied to a color television will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an embodiment of an interpolation circuit according to the present invention. In FIG.

Comma-corrected comma-corrected red, green, and evening primary color signals from television cameras and television receivers V positive, v'
η and V100 are the same interpolation circuit IR.

1o, 1B. Interpolation circuit 1a, 1a.

Since the configuration of IB may be almost the same, the interpolation circuit 1R for the primary color signal y''E will be explained.

In the interpolation circuit 1d, the input primary color signal Vπ is.

The nonlinear conversion circuit 2 converts the signal r into a signal r that is approximated by the linear signal 1°<v'π7 in the sense of the human eye. This conversion can be achieved by using non-linear excursions such as diodes in analog processing, or by conversion using ROM (read only memory) in digital processing. The converted primary color signal r is a time F which also has a delayed output.
The signal is input to the wave generator 3. The delayed output outputs an input signal that has compensated for the delay caused by the F wave.

The temporal p-wave unit 3 is a circuit that suppresses temporal changes on the television screen (extracts temporal low frequency components), and for example,
The structure shown in FIG. 2 or 3 can be used. The time p-wave generator shown in FIG. 2 has an input signal and a frame delay circuit 4 (
In the case of the NTSC system, there is a delay of 525 running line periods, and P
(with a delay of 625 scanning line periods in the case of AL and SECAM systems) is calculated by the difference circuit 5, and then
The sum circuit 7 adds the coefficient α to the output of the frame delay circuit 5 to obtain the door flow device output and the input to the frame delay circuit 5. The delay circuit used in the present invention, such as a frame delay circuit, can be realized by a semiconductor memory circuit or the like, and does not necessarily handle the entire period of the signal, but can also exclude the blanking period.

The coefficient α is a number greater than zero and less than one.

The smaller the value, the more suppressed the change in output, and for a normal screen, approximately 0.5 is appropriate. Although the input is directly output as the delayed output in FIG. 2, a frame delay circuit may be inserted if the coefficient α is made small. The time waver shown in Fig. 3 connects frame delay circuits 8 and 9 in cascade, adds input signals, and adds the human input signal and the output signals of frame delay circuits 8 and 9 by a load addition circuit 10 with a load of 7°11. This is a 2'4 transversal type P-wave device, and the delayed output is the output of the frame delay circuit 8. If you want to further suppress time changes depending on the content of the screen.

It is sufficient to increase the number of frame delay circuits and increase the number of inputs to the load addition circuit while keeping the sum of the loads at 1.

Returning to FIG. 1, the output of the 1-hour F wave generator 3 is differenced from the delayed output by a difference circuit 11 and is then applied to a delay circuit 12. The output of the difference circuit 11 is a signal (temporal high frequency signal) containing many components corresponding to changes in the screen of the input signal r, and is a two-dimensional door filter 13 that also includes inter-field processing.
given to.

The delay circuit 12 is a delay circuit having a signal delay approximately equal to the signal delay caused by the F-wave device 13.

The two-dimensional wave device 13 also has a delayed output like the F wave device 3,
For example, the configuration shown in FIG. 4 may be used. In the two-dimensional door transducer shown in FIG. 4, the input signal is transmitted to the cascaded scanning line delay circuits 14. Field delay circuits 15 and 16 (N
262 scan line period delay for TSC system, PAL and S
In the case of ECAM universal type, 612 scanning line delays), scanning line delay circuits 17 and their input/output signals "8'8'2'
8' is applied to an inter-field low-pass p-wave generator consisting of a load adder circuit 18 that adds a load of 8'. The field interval F
Similarly, the output of the waveform generator is sent to the scanning line delay circuits 19 and 2.
0 and 4'2' 4 are applied to a low frequency p-wave generator in the vertical direction of the screen, which is composed of a load adding circuit 21.

The output is further applied to a second horizontal low-frequency wave filter consisting of two-pixel delay circuits 25 and 26 and a 4'2'4 weight addition circuit 27, and the output is fed to a low-frequency wave filter, which is a p-wave generator. This becomes the output. The delayed output is obtained by delaying the output of the field delay circuit 15 by the scanning line delay circuit 28 and the 3-pixel delay circuit 29.

The passband of the two-dimensional filter in Fig. 4 is 2 as shown by the diagonal line in Fig. 5 when the pixel delay is the sampling period in processing by sampling at a frequency four times the color subcarrier in the NTSC system.
dimensional spatial frequency band.

That is, the frequency is 525/8 (line/height) or less in the vertical direction and 1.8 MHz or less in the horizontal direction.

Returning to FIG. 1, the output of the two-dimensional door transducer 13 is as follows.

A difference circuit 30 takes the difference from the delayed output, and a sum circuit 31 adds it to the temporal low frequency component of the input signal from the delay circuit 12.

The output of the difference circuit 30 is a temporally and spatially high-frequency component corresponding to the edges and fine structure of the changing component of one screen.
The signal is applied to the time compression circuit 32.

The time compression circuit 31 compresses the time of the input signal in half in response to sequential scanning on the display side and adjusts its amplitude. Since the output of the time compression circuit 32 is output only every other scanning line in sequential scanning, the amplitude is approximately doubled, but it may be shifted by a factor of 9 to 9 depending on the image quality preference. As the time compression circuit, for example, the one shown in FIG. 6 can be used.

In the time compression circuit of FIG. 6, the input signals are 1,
The signal is delayed by a delay circuit 33A for combining with a delay due to interpolation other than high-frequency components, which will be described later. The delayed signal is input to a buffer memory circuit 3311 having a capacity for one scanning line,
The output is doubled by the coefficient circuit 34 and sent to the time compression circuit 3.
The output will be 2.

In the case of digital processing, the coefficient circuit 34 can be realized by simply shifting digits. The buffer memory circuit 33B.

It is a memory circuit that can perform writing and reading independently, and is driven by a write command signal, a write address signal, a continuation command signal, and a read address signal from the read/write control circuit 35. Buffer storage circuit 33f (ha.

Under the control of the write/read control circuit 35, from the time when the input signal has been written to more than half of the scanning line, the scanning line is read out once from the beginning to the end at twice the writing speed. Further, the buffer storage circuit 33B outputs the signal level at zero when no reading is performed. As a result, the input signal is time-compressed in half in units of scanning lines, and becomes a signal that is output every other scanning line in the sequential scanning stage.

On the other hand, returning to FIG. 1, the input signal r of the output of the summation circuit 31
The signal from which temporal and spatial high-frequency components have been subtracted from the signal is interpolated by a conventional interlaced scan-to-progressive scan conversion interpolation circuit 36. As the interpolation circuit 36, for example, one shown in FIG. 7 can be used.

In the interpolation circuit shown in FIG. 7, the human input signal is added to a field delay circuit 37 (which may be the same as 15 and 16), a scanning line delay circuit 38, and a field delay circuit 39 connected in cascade. The output of 38 is input to a time compression buffer memory circuit 40 as an original scanning line signal.

The human input signal and the output signal of the field delay circuit 39 are averaged by an averaging circuit 41, and a variable coefficient lj is added to the signal by a coefficient circuit 42 as an interpolation scanning line signal when there is no temporal change in the input signal, and then the average circuit 43 is applied to one input terminal of . On the other hand, the input and output signals of the scanning line delay circuit 38 are averaged by an averaging circuit 44, and a variable coefficient (1-β) is calculated by a coefficient circuit 45 as an interpolation scanning line signal when there is a temporal change in the human input signal. is multiplied by , and applied to the other input of the averaging circuit 43 . The averaging circuit 43 averages the outputs of the coefficient circuits 42 and 45 and inputs the averaged signal to the buffer storage circuit 46 as an interpolation scanning line signal. Further, the difference between the input signal of the field delay circuit 37 and the output signal of the field delay circuit 39 generated by the difference circuit 47 is given to the motion detection circuit 48, and the difference between the variable coefficients β of the coefficient circuits 42 and 45 and (1 −β).

The motion detection circuit 48 uses the amplitude of the output of the difference circuit 47 to
A control signal is given to the coefficient circuits 42 and 45 such that the smaller the amplitude, the larger the coefficient β, and the smaller the amplitude, the smaller the coefficient β.

As a result, the interpolated scanning line signal output from the averaging circuit 43 changes from the average signal of the scanning lines of the previous and subsequent frames to the average signal of the upper and lower scanning lines of 1 depending on the width of the screen movement (change) of the input signal. It will change between. In addition, Vl, v
If the '75°V'B input signal is separated from a composite color television signal, the control signal may also be derived from another motion detection performed at the composite color television signal stage or at an intermediate stage of separation. As shown by the dotted lines in FIGS. 1 and 3, the detection accuracy can be increased by inputting the signal to the motion detection circuit 48 (in the case of an input signal from a camera, for example, information about the movement of the camera itself can be controlled). (Can also be used as a signal). Finally, buffer memory circuits 40 and 46 similar to buffer memory circuit 33B having a capacity for one scanning line are shown.
The time of the input signal is compressed in half by the write command signal, write address signal, read command signal, and read address signal from the write/read control circuit 49, and the switching signal from the write/read control circuit 49 is switch 5 controlled by
0, they are arranged in scanning line units in the order of sequential scanning. In other words, the signal of the current scanning line input to the memory circuit 40 is read out at twice the writing speed from the point when it is written to the center of the scanning line, and the signal of the interpolated scanning line input to the memory circuit 46 is read out from the point where the scanning line reaches the center. The data is read out at twice the speed from the time when writing is completed, and the re-output readout period is selected by the switch 50 to become a sequential scanning signal of the interpolation circuit output.

Returning to Figure 1, the time compression circuit 32 and interpolation circuit 36
The outputs are summed by a summation circuit 51 and interpolated in a sequential scanning manner to form an fc-r signal, that is, an r'-fold signal. In addition,
The period during which the output signal of the time compression circuit 32 is not zero is made to coincide with the period of the current scanning line of the output of the interpolation circuit 36. That is, when using the time compression circuit of FIG. 6 and the interpolation circuit of FIG. 7, the delay of the delay circuit 33A may be set to 263 scanning lines, and the writing and reading of the memory circuit 33B may be made the same as that of the memory circuit 40. Finally, the output signal r' of the summation circuit 51 is
In order to reversely convert a linear signal in the sense of the human eye into a signal for driving a color picture tube, it is supplied to a nonlinear conversion circuit 52 that performs a conversion approximating V7I, and is converted into a sequential scanning signal by an interpolation circuit IR. The resulting output signal becomes Vπ7.

As explained above, according to the configuration shown in FIG.

Difference circuit 30 which is a high frequency component both temporally and spatially
It is possible to interpolate and convert an input television signal of interlaced scanning into a television signal of progressive scanning by using the output of 11 of interlaced scanning with equal constraints in progressive scanning.

Although one embodiment of the invention has been described above, the present invention can be modified as follows in keeping with the spirit thereof.

In the above explanation, the present invention is applied to each of the three primary color signals, but even if applied only to the luminance signal,
Since the resolution of the human eye color is low, a sufficient image quality improvement effect can be obtained. This is NTSC, PAL, S
It can be applied to luminance signals of not only ECAM systems but also MAC (Multiflex, Analog, Component) systems, and, for example, No. 1 Vision system.

Next, in the configuration shown in FIG. 1, high frequency components are scanned temporally and spatially by interlaced scanning, but in order to reduce the circuit scale, for example, a two-dimensional wave filter 13 and a delay circuit 1 are used.
2 is omitted and the difference circuit 11, time compression circuit 32, and time F
Even if the transducer output of the transducer 3 is directly connected to the interpolation circuit 36 and the entire temporal high frequency component is subjected to interlaced scanning 11, a large improvement in image quality can be obtained compared to the prior art. In FIG. 1, the distribution of temporal high frequency components to the time compression circuit 32 and the interpolation circuit 36 is performed by the two-dimensional wave filter 13 and the difference circuit 30, but this distribution is performed by, for example, not only the high frequency components themselves but also the source. Depending on the local characteristics of the screen (for example, the height and amplitude of the inter-wall frequency component), including the TV No. 1, it is also possible to divide by multiplying the coefficient μ by a coefficient such as (l-β) in Figure 7. can.

The input/output nonlinear conversion circuits 2 and 52 of the interpolation circuit of the present invention may be omitted or fC may be simplified. For example, when dealing only with screens with low contrast, there is no problem in omitting the nonlinearity of the system. Furthermore, in many cases, it may be simplified to the inverse transformation of comma correction and its inverse transformation. moreover,
It is a natural variation to change the characteristics of the non-linear transformation depending on the comma for imaging and display, or for processing other than the human eye, for example, mechanical reading.

Even better, in the configuration of FIG. 1, each component is independent, but in order to reduce the circuit scale, delay circuits and the like can be shared between the valley components. Furthermore, the interpolation circuit of the present invention can be used not only internally, but also with a luminance signal and color difference signal separation circuit of a composite color television (1).

Finally, although the description in Part 1 has been made in which the input signal is an interlaced television signal, the present invention can be applied, for example, if the input signal itself is sequentially scanned and has a number of scan lines and/or frames. It can be applied to a scanning line interpolation circuit that uses interpolation and time compression to increase the number of scanning lines per time, such as doubling the number of scanning lines per time. In the above example, examples of signal components that only perform time compression include vertical high-frequency components when the number of scanning lines per frame is doubled, and interlaced scanning signals when the number of frames is also doubled. Similarly, there are high-frequency components both temporally and spatially.

〔Effect of the invention] As explained in detail above, according to the present invention.

Since the number of scanning lines can be converted without interpolating signal components that correspond to temporal changes in the screen, the image quality of moving images has been improved compared to conventional circuits. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIGS. 2 and 3 are configuration examples of the time p-wave generator in FIG. 1, and FIG.
An example of the configuration of a dimensional door transducer, FIG. 5 is a drawing showing the passage characteristics of the two-dimensional door transducer shown in FIG. 4, FIG. 6 is an example of the configuration of the time compression circuit in FIG. 1, and FIG. This is an example of the configuration of an interpolation circuit. IR, IC, III, 36-・Interpolation circuit, 2.52
---Nonlinear conversion circuit, 3... Time p-wave unit, 4, 8.
9...Frame delay circuit, 5, 11, 30.47...
・Difference circuit, 6,34...Coefficient circuit, 7,31.51・
...Sum circuit, 10.18, 21, 24.27...Load addition circuit, 12.33A...Delay circuit, 13...2
Dimensional door wave device, 14, 17, 19, 20, 28. 38...
・Scanning line delay circuit, 15, 16, 37.39... Field delay circuit, 22.23... Pixel delay circuit, 25° 26... 2 pixel delay circuit, 29... 3 pixel delay circuit, 33B, 40.46...Buffer memory circuit, 35.49
...Write/read control circuit, 41, 43.44... Average circuit, 42.45... Variable coefficient circuit, 48... Motion detection circuit, 50... Switch.

Claims (1)

[Claims] 1. In a scanning line interpolation circuit that converts an input television signal into an output television signal with a larger number of scanning lines by interpolation and time compression, the input television signal is added to the converted output television signal. 1. A scanning line interpolation circuit comprising means for configuring a part of a signal as a signal obtained only by time compression. 2. The scanning line interpolation circuit according to item 1, wherein the input television signal is an interlaced scanning television signal, and the output television signal is a progressive scanning television signal. interpolation circuit. 3. In paragraph 1 or 2, the scanning line interpolation circuit is configured by providing a nonlinear conversion circuit that performs nonlinearity correction and inverse correction by gamma correction at the input and output of the scanning line interpolation circuit. A scanning line interpolation circuit characterized by: 4. In the first, second, or third paragraph, the scanning line interpolation circuit is characterized in that the amplitude of the time-compressed signal component is doubled compared to the input signal. Scan line interpolation circuit.