JPH05284541A - Scanning line converter - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution to reduce the cost of the device by reducing an I signal and a Q signal to 1/n by thinning and compressing their time bases. CONSTITUTION:An I signal and a Q signal are supplied to time base compressing circuits 4 and 5 after having the bands limited for the purpose of preventing the occurrence of turnback distortion at the time of thinning processing to be next executed in LPFs 2 and 3. Time base compressing circuits 4 and 5 reduce the I signal and the Q signal to 1/n by thinning and compress the time bases so that these signals are within a horizontal retrace period, and they are supplied to an adder 6 as signals (e) and (f). The vertical filter output signal supplied to a positioning memory 8 through the adder 6 and a timewise variable vertical filter 7 is subjected to scanning line conversion processing and is supplied to a blanking circuit 9 and time base expanding circuits 10 and 11. Time base expanding circuits 10 and 11 increase I and Q signals (n) times and expand the time bases in the video signal period, and unnecessary frequency components are eliminated by LPFs 12 and 13 to calculate I and Q signals after scanning line conversion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning line conversion device for converting scanning lines of an image signal, and more particularly to a scanning device used in a transmission device and a reception device of a next-generation television signal or a converter device between different signal systems. The present invention relates to a line conversion device.

[0002]

2. Description of the Related Art As a broadcasting system that requires scanning line conversion processing, there is, for example, the letterbox system. The letterbox system is one of the systems proposed for the next-generation television system (EDTV) and is compatible with the current NTSC color television system. The letter box method will be described with reference to FIG.

On the transmitting side, a video signal having an aspect ratio of 16: 9 is used as a video source, and 480 effective scanning lines out of 525 are vertically compressed by 3/4 to form a main panel of 360, The panel serves as a non-picture portion, and an auxiliary signal such as a high-frequency signal in the horizontal or vertical direction is multiplexed on the non-picture portion so as to be inconspicuous. When this is received by the current television receiver, an image as shown in FIG. 7 (a) is obtained. On the other hand, when received by the EDTV receiver, an image having an aspect ratio of 16: 9 is displayed as shown in FIG. 7 (b). In an EDTV receiver, it is necessary to convert an image composed of 360 scanning lines into an image composed of 480 scanning lines by a scanning line conversion process.

Next, the scanning line conversion processing in this case will be described with reference to FIG. Scan line conversion is vertical sampling frequency conversion, which can be realized as follows. In FIG. 8A, first, the vertical sampling frequency is 36
Input signal of 0 cph is quadrupled 1440c by zero insertion
Uprate to ph. Next, a frequency component that is folded back at the down rate is removed by a low pass filter (hereinafter referred to as LPF). Finally, the signal is down-sampled by 1/3 to obtain a signal having a vertical sampling frequency of 480 cph.

Actually, it is not necessary to calculate the scanning lines thinned out at the down rate, so that only the output scanning lines can be calculated by filtering as shown in FIG. 8B.
Further, since the zero insertion point generated at the up rate can be ignored, it suffices to perform filtering with a different coefficient for each scanning line as shown in FIG. 8 (c). A time-varying vertical filter (a characteristic of which changes with time) for realizing such filtering is configured as shown in FIG. 6, for example.

The signal supplied to the input terminal (20) is composed of four vertical filters (21), (22), (2) having different coefficients.
3) and (24), and their outputs are selected by the multiplexer (25) according to the line information. The selected vertical filter output signal is rearranged into a desired scanning line series by a positioning memory or the like, and the scanning line conversion process is completed.

Such scanning line conversion processing needs to be performed on each of the luminance signal Y and the I and Q signals, and its hardware is constructed as shown in FIG. 5, for example.
The time-varying vertical filters (14), (15), (16) and the positioning memories (17), (18), (19) are assigned to the luminance signals Y, I signals, and Q signals, respectively, and scan independently. Line conversion processing is executed. In the above configuration, the time-varying vertical filters (14), (15), (1
6) requires a large number of line memories and multipliers, and the positioning memory may require a memory amount of 1 frame although it depends on the desired scanning line form.

[0008]

In the conventional scanning line conversion apparatus, a scanning line conversion circuit composed of a time-varying vertical filter and a positioning memory is provided independently for each of the luminance signals Y, I signals and Q signals, and three systems are provided. Since it was necessary, the scale of the circuit configuration was enormous. Therefore, the cost of the receiver becomes very high, which hinders the spread of the receiver.

[0009]

In order to solve the above problems, the present invention provides a scanning line conversion apparatus for vertically compressing or decompressing an image signal composed of a luminance signal Y and an I signal and a Q signal. A time axis compression unit that thins out pixels of the signal and the Q signal to 1 / n, and compresses the thinned I signal and the Q signal so that they fall within the horizontal blanking period, and the time axis compression unit. By the multiplexing means for multiplexing the I signal and the Q signal whose time axis is compressed by the horizontal blanking period of the luminance signal Y, and the scanning line conversion of the luminance signal Y in which the I signal and the Q signal are multiplexed during the horizontal blanking period. Scanning line converting means and a time axis for time-axis expanding the I signal and the Q signal multiplexed in the horizontal blanking period of the luminance signal Y subjected to the scanning line conversion by the scanning line converting means in the video signal period. Decompressor and remove unnecessary components in terms of frequency Comprising a low-pass filter means, I
The signal and the Q signal are multiplexed in the horizontal blanking period of the luminance signal Y, and then the scanning line conversion is performed on the signal.

[0010]

According to the above construction, the I signal and the Q signal whose time axis is compressed by the time axis compression means are multiplexed by the multiplexing means in the horizontal blanking period of the luminance signal Y to form one system signal. Scanning line conversion processing is performed on the signals of the system to convert them into desired scanning lines.

[0011]

1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing signal waveforms of respective parts in FIG. Figure 1
The scanning line conversion circuit shown in (1) has the following configuration. In FIG. 1, (1) is a blanking circuit for blanking the horizontal blanking period of the luminance signal Y, and (2) and (3) are LPFs (low-pass filters) for limiting the bands of the I signal and the Q signal, respectively. And (4) and (5) are time axis compression circuits configured by a memory or the like for thinning the I signal and the Q signal to 1 / n and compressing the time axis.

(6) is an adder for adding the respective outputs of the blanking circuit (1) and the time axis compression circuits (4) and (5), and (7) is a coefficient as already described in FIG. Vertical filters (21), (22), (2
3) and (24), and a multiplexer (25) for selecting the output of each vertical filter according to the line information, and (8) is a time-varying vertical filter (7) that outputs the desired output. This is a positioning memory that sorts into a scanning line series.

(9) is the positioning memory (8)
Is a blanking circuit for blanking a horizontal blanking period of the output signal of (10) and (11), and I and Q signals superimposed on the horizontal blanking period of the output signal of the positioning memory (8). Is a time-axis conversion circuit that up-times n times and returns to the original time axis.
2) and (13) are LPFs that remove unnecessary components of the I and Q signals output from the time axis conversion circuits (10) and (11).

Since the embodiment of the present invention has the above-mentioned structure, the luminance signal Y as shown in FIG.
Is supplied to the blanking circuit (1) and, after blanking the horizontal blanking period as shown in FIG. 2B, is supplied to the adder (6).

On the other hand, the input I signal and Q signal as shown in FIGS. 2 (c) and 2 (d) are supplied to LPFs (2) and (3), respectively, and the LPFs (2) and (3) respectively. Band limiting is performed so that aliasing distortion does not occur during the next thinning process, and the result is supplied to the time axis conversion circuits (4) and (5) in the next stage.

The time axis conversion circuits (4) and (5) are composed of a memory or the like, thin the I signal and the Q signal to 1 / n, and compress the time axis so that they fall within the horizontal blanking period. And supplies it to the adder (6) as a signal as shown in FIGS.

In the adder (6), the luminance signal Y blanked in the horizontal blanking period shown in FIG. 2 (b) and the time axis shown in FIGS. 2 (e) and (f) are compressed. The I signal and the Q signal are added, and a single video signal in which the I signal and the Q signal compressed in the horizontal blanking period of the luminance signal Y as shown in FIG. One video signal is supplied to the next time-varying vertical filter (7).

The time-varying vertical filter (7) has the same structure as that shown in FIG. 6 in the above-mentioned conventional example.
In the single video signal in which the I signal and the Q signal are multiplexed in the horizontal blanking period of the luminance signal Y shown in (1), a plurality of vertical filters (21), (22), which have different predetermined filter coefficients,
The signals are supplied to (23) and (24), filtered by different filter coefficients for each scanning line, guided to a multiplexer (25), and selected and output according to the line information from the multiplexer (25).

The vertical filter output signal selected and output by the time-varying vertical filter (7) is guided to the positioning memory (8), rearranged into a desired scanning line series in the positioning memory (8), and scanning line conversion is performed. The processed output signal is derived as shown in FIG. 2 (h) and is supplied to the blanking circuit (9), the time axis expansion circuits (10) and (11).

The blanking circuit (9) blanks the horizontal blanking period in which the I signal and the Q signal are multiplexed,
A luminance signal Y after scanning line conversion in which the horizontal blanking period is blanked as shown in FIG. 2 (i) is derived. in this case,
Instead of performing blanking in the horizontal blanking period, a synchronization signal may be added.

On the other hand, the time axis expansion circuits (10) and (1
In 1), the I signal and the Q signal multiplexed within the horizontal blanking period of the luminance signal Y are taken out, the I signal and the Q signal are up-rated by n times, and the time axis is extended in the video signal period. Then, the I signal and the Q signal whose time axis is adjusted to the video signal period are supplied to LPFs (12) and (13) to remove unnecessary components in terms of frequency, and as shown in FIGS. 2 (j) and (k). It is derived as I and Q signals after scanning line conversion as shown.

Next, the I signal and the Q signal are multiplexed in the horizontal blanking period, and the I signal and the Q signal are multiplexed in the horizontal blanking period.
The down rate 1 / n at the time of decimation and interpolation performed to restore the signal and the value of n in the up rate n will be described.

The television signal of the NTSC system is 14.
A case where sampling is performed at a frequency of 3 MHz (4 fsc) is illustrated. In this case, the sampling frequency is 1
Since the frequency is 4.3 MHz, about 910 samplings are performed in one horizontal period. Now, if n = 10, it becomes possible to allocate 150 samples in the color signal period composed of the I signal and the Q signal and 750 samples in the video signal period as shown in FIG.

In the color signal band, as shown in FIG. 3, the sampling frequency of the color signal becomes 1.43 MHz, which is 1/10 of n, by thinning out, so that the band of the I signal and the band of the Q signal are both 0. It becomes 7MHz.

When the value of n is larger than 10, the band of the color signal becomes insufficient, and when the value of n is smaller than 10, the I signal and the Q signal cannot fit within the horizontal period of the video signal. Thus, in the NTSC system, the scanning line conversion of the present invention can be effectively performed by setting the value of n to n = 10. It should be noted that the value of n may be appropriately selected depending on the video signal transmission method.

[0026]

As described above, the present invention can provide a scan conversion system composed of a time-varying vertical filter and a positioning memory as one system, simplifying the circuit configuration and providing an inexpensive scan line conversion apparatus. can do.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention, and is a diagram showing signal waveforms of respective parts of FIG. 1;

FIG. 3 is an operation explanatory diagram of the present invention, and is a frequency spectrum diagram when color signals are multiplexed in a horizontal blanking period.

FIG. 4 is an explanatory diagram of a signal form of the present invention.

FIG. 5 is a configuration diagram of a main part of a conventional example.

FIG. 6 is a configuration diagram of a time-varying vertical filter.

FIG. 7 is an explanatory diagram of a letterbox method.

FIG. 8 is an explanatory diagram of scanning line conversion.

[Explanation of symbols]

 4,5 Time axis compression circuit 6 Adder 10,11 Time axis expansion circuit 12,13 LPF

Claims (1)

[Claims] 1. A scanning line conversion apparatus for vertically compressing or expanding an image signal composed of a luminance signal Y, an I signal and a Q signal, in which pixels of the I signal and Q signal are thinned to 1 / n and Time axis compression means for compressing the drawn I signal and Q signal so that they fit within the horizontal blanking period, and I and Q signals whose time axis is compressed by the time axis compression means are luminance signals. Multiplexing means for multiplexing in the horizontal blanking period of Y, scanning line converting means for scanning line converting the luminance signal Y in which I and Q signals are multiplexed in the horizontal blanking period, and scanning line conversion by the scanning line converting means. A time axis expanding means for expanding the I signal and Q signal multiplexed in the horizontal blanking period of the luminance signal Y subjected to the time axis in the video signal period, and a low-pass filter for removing unnecessary components in terms of frequency. Equipped with means,
A scanning line conversion device, wherein the I signal and the Q signal are multiplexed in the horizontal blanking period of the luminance signal Y and then the scanning line conversion is performed on the signal.