JPH01295591A - Television signal time base multiplexer - Google Patents

Abstract

PURPOSE:To improve the S/N of a color signal by quantizing a color signal whose amplitude is concentration to a comparatively small amplitude by a quantizing bit number more than a Y signal and applying nonlinear quantization so as to emphasize a small amplitude part. CONSTITUTION:An RGB signal is converted into a Y signal and Cw, Cn signals by a matrix circuit 1. The Cw, Cn signals are quantized by a quantization bit number more than that for the Y signal for later nonlinear quantization and subject ti line sequential processing in a vertical direction low pass filter 6. The quantized bit number is reduced to the quantization bit number of the Y signal in a data conversion circuit 20 and converted into a nonlinear quantization data. Thus, the S/N of the color signal is improved and even to a picture whose amplitude of the color signal is increased such as a color bar, the amplitude is sent as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television signal time domain multiplexing device for time domain multiplexing and transmission of television luminance signals and color signals.

[Prior art] Figure 3 shows, for example, the Technical Report IC55 of the Television Society of Japan.
6-4. It is a block diagram showing the configuration of a conventional time axis multiplexing device shown in "High Definition Television TCI Satellite Transmission System", and FIG. 3 (A) is a block diagram of the transmission system, and FIG.
) shows a block diagram of the receiving system, in which (1)
The three primary color signals R, G, and B signals (hereinafter referred to as RGB signals) are divided into a luminance signal (hereinafter referred to as Y signal), a wideband color signal (hereinafter referred to as Cw multiplied signal), and a narrowband color signal (hereinafter referred to as Cw multiplied signal).
(2) A matrix circuit that converts the Cn signal into
, (3), (4) and (11) are A/D conversion circuits, (
5) and (14) are delay lines that give a certain time delay to the signal, (6) is a vertical low-pass filter, and (7)
, (8), (12), and (13) are the Cw multiplied signal Cn signal l
(9) is a selector circuit for time-axis multiplexing the Y signal and the color signal of the Cw multiplied signal Cn signal; (10), (16), (17), and (18) are D
/A conversion circuit, (is) is a vertical interpolation filter, (
19) is an inverse matrix circuit that converts the Y signal and the Cw multiplied signal Cn signal into RGB signals.

Next, the operation of the above configuration will be explained. Here, we take a high-definition television signal as an example, and the following matrix is not shown between the input RGB signal, Y signal, and Cw multiplied signal Cn signal, and on the transmitting side, the input RGB signal is In the matrix circuit (1), the Y signal determined by the above matrix and the Cw multiplied signal Cn signal are converted, and then inputted to the A/D conversion circuits (2), (3), and (4), respectively, and converted into digital signals. Ru. The Cw multiplied signal converted into a digital signal in this way and the Cn
The signal is input to a vertical low-pass filter (6), where processing is performed to alternately select and transmit the Cw multiplied signal Cn signal line by line, that is, line sequential processing. In this vertical low-pass filter (6), C
After limiting the band of the vertical frequency component to prevent aliasing of the vertical frequency component that occurs when the w-fold signal and the Cn signal are transmitted every other line, the Cw-fold signal C is transmitted.
n signals are output alternately, and this output is written to memory (7) or (8). This memory (7) and (8)
Writing is performed alternately for every l line, and writing is performed on one at the read timing of the other. Furthermore, reading from the memory (7) or (8) is performed at a higher speed than writing, thereby compressing the time axis of the Cw multiplied signal Cn signal.

Then, the Cw times signal and Cn signal which have been compressed by 1 time axis are as follows.
The TCI (Ti
me Compressed Integration
) form a digital signal. Here, a delay line (5) is used to match the Y signal with the time delay of the Cw multiplied signal Cn signal that occurs in the vertical low-pass filter (6) and the memory (7) or (8).

TCICn digital signal /A created through the above process
After being converted into an analog signal by a conversion circuit (lO), it is transmitted.

Next, on the receiving side, the transmitted figure 4 (a)
The TCr signal shown in , (b) is sent to the A/D conversion circuit (11
), where it is converted into a digital signal, and then the Cw multiplied signal and Cn signal portion are written into the memory (12) or (13). This memory (12) and (
13), the Cw multiplied signal Cn signal is written alternately every l line. In this case, the sender's memory (7),
Contrary to (8), by performing reading at a slower speed than writing, the Cw times signal Cn signal, which has been compressed by one time axis, is restored to its original time axis.

Since the signals read from the memories (12) and (13) are Cw times Cn signals every other line,
Line interpolation is performed in a vertical interpolation filter (15). That is, the vertical interpolation filter (15
) by interpolating each Cw multiplied signal Cn signal, (:w, CnFq signal is obtained for all lines.

Then, C which is the output of the vertical interpolation filter (15)
w, Cn digital signals are sent to the D/A conversion circuit (17), (
18), it is converted into an analog signal. On the other hand, the Y signal is
After the timing with the Cw multiplied signal Cn signal is adjusted by the delay line (14), it is converted into an analog signal by the D/A conversion circuit 6). The Y signal and Cw multiplied signal Cn signal obtained by decoding the TCI signal in this manner are converted into RGB signals by an inverse matrix circuit (19), and then become output signals.

In the above configuration, the input RGB signal is converted into Y, Cw, Cn signals according to the above matrix, but C
In order to normalize the amplitude of the Y signal which is the amplitude of the w-fold signal Cn signal, it is multiplexed as Cw/1.26 and Cn/0.82. Furthermore, since the saturation of the image actually transmitted is low, the amplitude of the Cw multiplied signal Cn signal is transmitted with the amplitude 3 dB larger than the normalized amplitude, and the S/N of the Cw multiplied signal Cn signal is
The ratio has been improved.

[Problem 8 to be solved by the invention] In the conventional television signal time axis multiplexing device configured as described above, according to the above matrix,
When Y, Cw, and Cn signals are created, the amplitudes of the Cw and Cn signals are small in most images, so if they are A/D converted and time-axis multiplexed as they are, it is disadvantageous in terms of S/N ratio. - On the other hand, when A/D conversion is performed after increasing the amplitude of the Cw and Cn signals, it becomes necessary to limit the amplitude in images with high saturation such as color pars, and there is a problem that the original image cannot be restored. was there.

This invention was made to solve the above-mentioned problems, and when transmitting a Y signal and a color signal whose amplitude values are concentrated at relatively small values by time-axis multiplexing, the color signal Provides a television signal time axis multiplexing device that can improve the S/N ratio and also transmit images with large amplitude color signals, such as color pars, with their amplitude values intact. The purpose is to

[Means for Solving the Problems] A television signal time axis multiplexing device according to the present invention includes:
A/D conversion means for quantizing the color signal with a number of quantization bits greater than the number of quantization bits of the time axis multiplexed signal;
and nonlinear quantization means for converting the color signal digital data obtained by the D conversion means into digital data having a quantization bit number equal to the quantization bit number of the time-axis multiplexed signal. Features.

[Operation] According to the present invention, after the color signal is quantized with the number of quantization bits larger than the number of quantization bits of the one-time axis multiplexed signal, the quantization level of the time axis multiplexed signal is changed when the amplitude of the color signal is small. The quantized data can be made to correspond to each other by a nonlinear quantization means so that the amplitude becomes large in the quantized data.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of a television signal time axis multiplexing apparatus according to an embodiment of the present invention.
is a block diagram of the transmitting system, and FIG. 1 (B) is a block diagram of the receiving system. In FIG.
matrix circuit for converting signals into Cw and Cn signals, (2), (3).

(4), (11) are A/D conversion circuits, (5), (14)
) is a delay line, (6) is a vertical low-pass filter, (7), (8), (12), and (13) are memories with a capacity for Cw8 and Cnn signal l linearity, (9) is Y A selector circuit (10) for time-axis multiplexing by switching the signal and the time-axis converted Cw and Cn signals.

(16), (17), (18) are D/A conversion circuits, (1
5) is a vertical interpolation filter; (19) is an inverse matrix that converts the Y signal and Cw and Cn signals into RGB signals;
(20) is a data conversion circuit for converting the output data of the vertical low-pass filter (6) into non-linear quantized data of the quantization bit number of the time domain multiplexed signal; (21) is the data conversion circuit (20) This is a data inversion circuit for performing data conversion with the input/output relationship reversed. Here, the data conversion circuit (20) corresponds to nonlinear quantization means.

Next, the operation of the above configuration will be explained.

First, on the transmitting side, an RGB signal, which is an input video signal, is converted into a Y signal and Cw and Cn signals by a matrix circuit (1). After the Y signal, Cw, and Cn signals are each limited to the required band, they are sent to the A/D conversion circuit (2).
, (3), (4) are input and become digital data.

Here, the Cw and Cn signals are quantized with a larger number of quantization bits than the Y signal for later nonlinear quantization.

Next, the Cw and Cn signals are passed through a vertical low-pass filter (
6), and the vertical low-pass filter (6) outputs the Cw signal and the Cn signal alternately every l line. The output of the vertical low-pass filter (6) is subjected to a data conversion circuit (20) in which the number of quantization bits is reduced to the number of quantization bits of the Y signal.

Converted to nonlinear quantized data.

An example of the correspondence relationship here is shown in Figure 2, assuming that the number of quantization bits for the Y signal is 8, and the number of quantization bits for the Cw and Cn signals is 10.The Cw and Cn signals are centered around the center value of the input range. Due to the characteristics shown in FIG. 2, the amplitude becomes larger when the amplitude is small compared to the case where the entire area corresponds linearly.

In this way, the number of quantization bits is reduced in the data conversion circuit (20) and nonlinear quantization is performed on Cw and C.
The n signal data is stored in a memory (7) with a capacity for l lines.
, (8) are written alternately. This memory (7), (
8) The time axis of the Cw and Cn signals is compressed by reading from the data at a higher speed than writing.

The Cw and Cn signals time-base compressed in this way are input to the selector circuit (9), where they are time-base multiplexed into the Y signal and then D/A converted to form a time-base multiplexed signal. A delay line (5) inserted into the Y signal system is used to match the timing of the Y signal and the time-axis compressed Cw and Cn signals.

Next, on the receiving side, the time-domain multiplexed signal is input to the A/D converter (11), where it is converted into digital data, and then the Cw%Cn signal portion is written to the memory (12) or (13). . here.

Since the Cw and Cn signals are input alternately every l line,
One is written to the memory (12) and the other is written to the memory (13), and while writing to the memory (12) is being performed, reading from the memory (13) is performed, and vice versa. ) will be read from the memory (12).

Contrary to the transmission side, reading from the memories (12) and (13) is performed at a slower speed than writing, and the time axis of the read signal returns to the original.

C read from the above memory (12) or (13)
The w and Cn signal data are input to the circuit (21), where the input/output relationship is reversed from that in Fig. 2, and the original Cw
, Cn signal data. Since the output of the data inverse conversion circuit (21) is a Cw and Cn signal that alternates line by line, the Cw and Cn signals of all lines are obtained by the vertical interpolation filter (15).

Next, the Cw and Cn signal data line-interpolated by the vertical interpolation filter (15) are sent to the D/A conversion circuit (17),
It is converted into an analog signal at (18) and inputted together with the Y signal to an inverse matrix circuit (19) to obtain an output RGB signal. On the other hand, the Y signal is Cw at the delay line (14).
, after timing alignment with the Cn signal,
It becomes an analog signal in the D/A conversion circuit (16).

The data conversion circuit (20) and data inverse conversion circuit (21) in the above embodiment can be easily realized using a read-only digital memory, that is, a ROM.

In other words, the input is the ROM address and the output is the RO
The characteristics shown in FIG. 2 may be written in the ROM in advance in correspondence with the data of M.

In the above embodiment, it is assumed that the color signals, that is, the Cw and Cn signals, are processed line-sequentially, but even if line-sequential processing is not performed, the above embodiment can be achieved by performing data conversion on each of the Cw and Cn signals. It has the same effect as.

Furthermore, the input/output relationship for data conversion is not limited to that shown in FIG. 2, and any curve may be used as long as it has a characteristic that emphasizes the small amplitude portion.

Further, in the above embodiment, the signal transmission is performed using an analog signal, but the same effect can be obtained even in the case of digital transmission. In the case of this digital transmission, since it corresponds to finely converting small amplitude value portions that have a high probability of appearing, it produces the same effect as analog transmission.

[Effects of the Invention] As described above, according to the present invention, after being quantized with a larger number of quantization bits than the Y signal, which is a color signal concentrated in a relatively small amplitude portion, the small amplitude portion is emphasized. Since it is configured to perform nonlinear quantization, it is possible to improve the S/N ratio of the color signal, and there is no need to limit the amplitude even in highly saturated images such as color pars, and the amplitude value can be transmitted as it is. At the same time, it is possible to reliably restore the original image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a television signal time axis multiplexing device according to an embodiment of the present invention, FIG. 2 is an input/output relationship diagram showing an example of nonlinear quantization characteristics used in the present invention, and FIG. 4 is a plot diagram showing the configuration of a conventional television signal time domain multiplexing apparatus, and FIG. 4 is a waveform diagram showing an example of a time domain multiplexing signal. (2), (3), (4)... A/D conversion circuit, (
6) -- Vertical low-pass filter, (9) -- Selector circuit, (20) -- Data conversion circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Analog-to-digital conversion that quantizes the chrominance signal with a larger number of quantization bits than the luminance signal in a television signal time-axis multiplexing device for time-axis multiplexing and transmitting the luminance signal and chrominance signal of the television signal. and nonlinear quantization means for reducing the number of quantization bits of a color signal and realizing nonlinear quantization characteristics.