JPS63142997A - Secret transmission equipment for color television signal - Google Patents

Abstract

PURPOSE:To prevent picture quality from being deteriorated, by separating a luminance signal from a chrominance signal in a color television signal in digitalwise, performing the replacement of a picture element only for the luminance signal, and synthesizing the chrominance signal without applying any processing with the luminance signal in which the replacement of the picture element is performed in the digitalwise. CONSTITUTION:The output digital data of an A/D converter 5 is separated to the luminance signal Y and the chrominance signal C by a Y/C separation circuit 31. The luminance signal Y is written on a line memory 6, and the picture element is replaced at random at the time of being read from the line memory 6 by a read only memory 9. The chrominance signal on one side is delayed by a time while the replacement of the picture element of the luminance signal is performed, by a delay circuit 32, and after that, it is synthesized with the luminance signal in which the picture element is replaced at every line unit. In such way, since a device is constituted so that the picture element of only the luminance signal is replaced at every line unit, the continuity of the phase of a chrominance carrier in the chrominance signal can be kept, an image in which the expansion of spectrum is suppressed and few deterioration in the picture quality is generated, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color television signal secret transmission device used for analog image transmission.

[Conventional technology]

FIG. 3 is an example of a block diagram of a concealing section of a conventional television signal concealed transmission device, in which (l) is an analog television signal input terminal, (21 is a buffer amplifier, (3
) is a low-pass filter, (4) is a synchronous extraction circuit, (6)
is the A10 converter, (6) is the line memory, (7) is the line memory write address generation counter, (8)
(9) is a read-only memory (ROM), (1o+) is a D/A converter, (11) is a low-pass filter, and (121 is an analog television signal output terminal).

Further, FIG. 4 is an example of a block diagram of a deciphering section of a conventional television signal concealing device, and (21) is an input i of a concealed analog television signal, [2u-
t buffer amplifier, (3) is a low pass filter, (4)
is a synchronous extraction circuit, (6) is an A/D converter, (6) is a line memory, (7) is a counter for generating a write address for the line memory, (8) is a counter for generating a read address, and (9) is a read-only Memory (ROM), (1
0) is a D/A converter, (Il+ is a low-pass filter, and a decrypted analog television signal is sent to it.

Next, the operation will be explained. In the hidden part of Figure 3,
The analog black-and-white television signal input to the buffer amplifier (2) is filtered by a low-pass filter (31K) to remove high-frequency noise components, and then converted into an A/
Sampled by D converter (5).

It is quantized and becomes a digital signal. The digitized input signal is sent to the write address generation counter (7).
is written for each horizontal line into a line memo (January 6), which has a memory capacity of one horizontal line of the television, according to the address where it occurs. Line memory +61H has a double buffer structure in line units, and each memory performs read and write operations alternately for each line. Next, when reading data line by line from the line memory (6), instead of reading data in the order in which they were written, the image is read out randomly for each pixel within the line, and by changing the order of the pixels within the line. Make it confidential. This change in the reading order is performed by the read-only memory IJ-+9+. The output of the line memory (6) whose reading order has been changed is converted into a concealed analog television signal by the D/A converter (lO), and outputted from the output terminal (12+).

The operation of the de-ciphering section in FIG. 4 is almost the same as that of the anonymizing section in FIG. 3, but when committing data to the line memory (6), the read order in the anonymizing section By writing to the line memory (6) in exactly the same order,
The anonymizing section shown in FIG. 3 restores the rearranged signal to the original signal.

[Problem that the invention seeks to solve]

The conventional television signal secret transmission device is configured as described above, so it works well for black and white television signals, but when applied to color television signals, the spectrum of the color signal (color subcarrier signal) widens, causing problems. There was a problem that the image quality deteriorated.

This invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to obtain a color television signal secret transmission device with less broadening of the color signal spectrum and less deterioration of image quality even when used for color television signals. With the goal.

[Means for solving problems]

The color television signal secret transmission device according to the present invention digitally separates the brightness signal and color signal in the color television signal, performs pixel ordering only for the brightness signal, and leaves the color signal as is without any processing. Furthermore, the luminance signal is digitally synthesized with the luminance signal after the pixel replacement.

[Effect]

The color television signal concealed transmission device according to the present invention replaces pixels only in the luminance signal in the color television signal, so that the phase continuity of the color subcarrier in the color signal is maintained, and therefore the concealed signal is The spread of the spectrum of analog television signals is suppressed, allowing for concealment with little deterioration in image quality.

[Husband example]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of an embodiment of the concealing section of the color television signal concealed transmission apparatus according to the present invention, and in FIG. 1, the same numbers as in FIG. 3 perform the same functions as in FIG. 3. It is something. In the figure, the luminance signal (Y)
A Y/C separation circuit for separating the color signal (C) from the color signal (C), and a delay circuit for delaying the color signal for a certain period of time while the pixels of the luminance signal are replaced in the line memory (6), j33)
is Y/ which combines the once separated luminance signal and color signal again
This is a C synthesis circuit.

FIG. 2 is a block diagram of an embodiment of the deciphering section of the color television signal concealed transmission apparatus according to the present invention, and the same numbers as in FIGS. It performs the same function as that shown in Fig. 4.

Next, the operation will be explained.

In the concealment section of FIG. 1, the process until the input analog television signal is converted into digital data by the A/D converter (6) is the same as the conventional case of FIG. 3.

The output digital data of the A/D converter (5) is Y
/C separation circuit rule, luminance signal (Y) and color signal (C)
separated into Y/C separation frequency f% (311 is composed of a so-called comb-shaped digital filter.
Of the luminance signal and color signal separated by the separation circuit A1), the luminance signal is written to the line memory (6), and when reading from the line memory (6), pixels are randomly replaced by the read-only memory (9). .

One color signal is delayed by the time delay circuit t32) that replaces the pixels of the luminance signal, and then Y/
The C synthesis circuit 9 synthesizes the pixels with a luminance signal that has been replaced on a line-by-line basis.

The Y/C combining circuit (33) is an adding circuit.

Next, in the de-ciphering section shown in FIG. 2, the digital data after A7'D conversion is separated into Y/C, and the luminance signal is written into the line memory (6) in the same way as the anonymizing section. , the original analog color television signal is restored by restoring the rearranged order of pixels in the concealment section.

〔Effect of the invention〕

As described above, according to the present invention, a color television signal is separated into a luminance signal and a color signal, and the pixels of only the luminance signal are replaced line by line, so that the phase of the color subcarrier in the color signal is continuous. This has the effect of maintaining image quality, suppressing spectrum broadening, and producing images with little deterioration in image quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a concealing section of a color television signal concealed transmission apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a deciphering section of a color television signal concealed transmission apparatus according to an embodiment of the present invention. 3 is a block diagram of a concealing section of a conventional television signal concealed transmission apparatus, and FIG. 4 is a block diagram of a deciphering section of a conventional television signal concealed transmission apparatus. In the figure, ell is a Y/C separation circuit, a is a delay circuit, and fin is a Y/C synthesis circuit. In the figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A device for concealing and deconceiving an analog composite color television signal, the device is composed of a concealment section and a deciphering section, and the concealment section transforms the inputted analog composite color television signal into a digital pixel signal. Y/C separation means that separates the digital pixel signal converted by the A/D conversion means into a luminance signal (Y) and a color signal (C); pixel exchanging means for exchanging pixels of the luminance signal separated by the means; delay means for delaying the color signal separated by the Y/C separation means for a certain period of time; It has a Y/C synthesis means for synthesizing the color signals output from the delay means, and a D/A conversion means for converting the output of the Y/C synthesis means into the original analog signal,
The deciphering section also includes an A/D conversion means for converting the concealed analog composite color television signal output from the anonymization section into a digital signal, and an output digital data luminance signal of the A/D conversion means. (Y) and color signal (C
); and pixel replacement means that performs pixel replacement of the luminance signal separated by the Y/C separation means in the opposite direction to that of the concealment unit to restore the original order. , a delay means for delaying the color signal separated by the Y/C separation means for a certain period of time; a Y/C synthesis means for synthesizing the luminance signal output from the pixel replacement means and the color signal output from the delay means; 1. A color television signal secret transmission apparatus, comprising: D/A converting means for converting the output of the /C combining means into an original analog signal.