JPH04252692A - Secrecy device for image signal - Google Patents

Abstract

PURPOSE:To improve the secrecy effect by changing the transmitting sequence of a scanning line signal in accordance with a scramble pattern stored in advance, at every area where one frame is divided into plural areas of a scanning line unit. CONSTITUTION:At the time of transmission, an odd/even control circuit 13 detects whether a processed field of an input image signal S1 is odd or even. An odd/even scrambling data storage circuit 14 scrambles an ascending write address outputted from a write address control circuit 12 in accordance with a scramble pattern corresponding to a result of its detection. In such a manner, in addition to scrambling by the change of a scanning line signal for constituting one frame, a double processing for dividing one frame into plural areas and varying a scrambling pattern at every area is executed, and the secrecy effect is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image signal concealment device used when transmitting an image signal, and more particularly to an image signal concealment device that improves the concealment effect.

0002

[Prior Art] Image signal concealment devices are used to prevent unauthorized viewing of paid TV programs, etc. Using digital technology, the transmitter mixes and transmits the image signal, and the receiver receives the original image signal. It's back to the image signal. This transmission method is called a scramble method.

[0003] Among the scrambled image signal transmission methods, there is a method in which a code (decryption code) is added to the transmitted television signal to change the transmission order of the image signal, but once the code is decoded, the scrambling effect disappears. To put it away,
Particularly when secrecy is required, a scrambling method that does not add encryption is used.

[0004] As an image signal concealing device that employs this scrambling method without adding a code, an image signal concealing device that replaces scanning line signals within one field is conventionally known.

[0005]

In the conventional image signal concealment device described above, since the concealment method is only to replace the scanning line signal within one field, there is a problem that it is relatively easy to decode.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image signal concealment device that can further enhance the concealment effect.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the invention according to the first claim provides a transmitting side that divides one frame into a plurality of areas in units of scanning lines and detects each area. area detecting means; scrambling pattern storage means for storing a scrambling pattern of a scanning line signal for each area divided by the transmitting side area detecting means; scrambling means for changing the transmission order of the scanning line signals according to a scrambling pattern stored in the pattern storage means; receiving side area detecting means for detecting each area divided by the transmitting side area detecting means on the receiving side; , a descrambling pattern storage means for storing a descrambling pattern for restoring the scanning line signal to the original order for each region divided by the transmitting region detecting means; The apparatus further includes a descrambling means for rearranging the scanning line signals to the original order according to the descrambling pattern stored in the descrambling pattern storage means for each area.

[0008] Further, the invention according to claim 2 is the image signal concealment device according to claim 1, wherein the transmitting side area detecting means and the receiving side area detecting means are constituted by odd numbered scanning line signals. The field detecting means is configured to detect an odd field consisting of a scan line signal of an even number and an even field consisting of even-numbered scanning line signals.

[0009]

[Operation] In the invention according to claim 1 configured as described above, the scramble pattern storage means on the transmission side stores the scramble pattern of the scanning line signal for each area divided by the transmission side area detection means. When the transmitting side area detecting means divides one frame into a plurality of areas in units of scanning lines and detects each area, the scrambling means stores the scrambling pattern storage means for each area detected by the transmitting side area detecting means. The transmission order of the scanning line signals is changed according to the stored scrambling pattern. Further, the descrambling pattern storage means on the receiving side stores a descrambling pattern for restoring the scanning line signal to the original order for each area divided by the above-mentioned transmitting side area detecting means, and When the means detects each area divided by the transmitting side area detecting means, the means detects the scanning line signal according to the descrambling pattern stored in the descrambling pattern storing means for each area detected by the receiving side area detecting means. Replace with original order.

Further, in the invention according to claim 2 configured as described above, in dividing one frame into a plurality of areas in units of scanning lines, the transmitting side area detecting means and the receiving side area detecting means are configured. The field detection means is
Each field is detected in order to divide one frame into an odd field made up of odd-numbered scanning line signals and an even field made up of even-numbered scanning line signals.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram of an image signal concealment device according to an embodiment of the present invention. In the figure, 1 is a transmitter that converts an input image signal S1 consisting of a plurality of scanning line signals into a secret signal S2 and transmits it, and 2 is a transmitter that converts the secret signal S2 back into the original image signal and outputs it as an output image signal S3. It is a receiving device.

In the receiving device 1, an A/D 11 converts the input image signal S1 from an analog signal to a digital signal.
a conversion circuit; 12 is a write address control circuit that performs phase processing on the input image signal S1 and creates a write address in digital processing; 13 is an odd (ODD) configured with even-numbered scanning line signals based on the input image signal S1;
An odd-even control circuit detects whether the field is a field or an even field consisting of odd-numbered scanning line signals, and 14 is information on switching of scanning line signals within one field in each of the odd field and even field. An odd-even scramble data storage circuit that stores a certain scramble pattern and converts the write address output from the write address control circuit 12 according to the scramble pattern selected under the control of the odd-even control circuit 13; 15 is odd-even scramble data; a memory circuit for temporarily storing data of the scrambled input image signal S1 by writing the digital signal output from the A/D conversion circuit 11 to the write address output from the memory circuit 14;
16 is a read address control circuit that outputs a read address for sequentially reading data written in the memory circuit 15; 17 is a read address control circuit that converts the digital signal read from the memory circuit 15 into an analog signal and outputs it as a secret signal S2. This is a D/A conversion circuit.

[0013] Also, in the receiving device 2, an A/21 converts the secret signal S2 from an analog signal to a digital signal.
A D conversion circuit, 22 is a write address control circuit that performs phase processing on the secret signal S2 and creates a write address in digital processing, 23 is a memory circuit for temporarily storing data of the secret signal S2 converted into a digital signal, and 24 is a A read address control circuit that generates an address for reading data written in the memory circuit 23, 25 an odd/even control circuit that detects whether it is an odd field or an even field, and 26 one field for each of the odd field and even field. The memory circuit 2 stores a descrambling pattern for restoring the scrambling caused by exchanging scanning line signals within the memory circuit 2 , and also stores a descrambling pattern in accordance with the descrambling pattern selected under the control of the odd-even control circuit 25 .
3 is an odd-even descramble data storage circuit that outputs the read address, and 27 is a D/A conversion circuit that converts the data read from the memory circuit 23 from a digital signal to an analog signal and outputs it as an output image signal S3. be.

Next, the operation of this embodiment having the above configuration will be explained. When the input image signal S1 is input to the transmitting device 1, the A/D conversion circuit 11 converts the input image signal S1 into a digital signal, and the write address control circuit 12 performs phase processing to convert the input image signal S1 into a digital signal according to the input order. The odd-even control circuit 13
detects whether the field being processed in the input image signal S1 is odd or even.

The odd-even control circuit 13 outputs the detection result to the odd-even scramble data storage circuit 14, and the odd-even scramble data storage circuit 14 selects a scramble pattern according to the detection result, and also The write address output by the write address control circuit 12 is converted according to the pattern.

The input image signal S1 converted into a digital signal by the A/D conversion circuit 11 is input to the memory circuit 15,
This odd-even scramble data storage circuit 14
is written to the write address output by . By determining the write address of the memory circuit 15 in the above manner, the scanning line signal of the input image signal S1 is replaced with different scrambling patterns depending on the odd field and even field, and the memory circuit 15
will be written to.

Next, the read address control circuit 16
A read address is output in order to read the data written in the memory circuit 15 in normal ascending order. As a result, the input image signal S1 is scrambled with different patterns depending on the odd field and the even field, and the scrambled signal is converted by the D/A conversion circuit 17 into a secret signal S2, which is an analog signal, and sent to the receiving device 2. is output to.

The A/D conversion circuit 21 in the receiving device 2 converts the input secret signal S2 from an analog signal to a digital signal, and the digital signal is sequentially sent to the memory according to the ascending write addresses output by the write address control circuit 22. It is written into the circuit 23. Therefore, data scrambled in different patterns depending on the odd field and even field is stored in the memory circuit 23.

Next, the read address control circuit 24
The read address in ascending order for the memory circuit 23 is output to the odd/even descramble data storage circuit 26, and the odd/even control circuit 25 outputs the read address to the odd/even descramble data storage circuit 26 depending on whether the target to be read is an odd field or an even field. Select a descrambling pattern for circuit 26. Then Odd
The even descramble data storage circuit 26 converts the ascending read addresses outputted by the read address control circuit 24 in a predetermined pattern according to the selected descrambling pattern and outputs the converted data to the memory circuit 23. As a result, the secret signal S2 is descrambled using a predetermined descrambling pattern in both the odd field and the even field, and the descrambled signal is converted into the output image signal S3, which is an analog signal, by the D/A conversion circuit 27. converted.

Note that the write addresses and read addresses for the memory circuits 15 and 23 are specified as V addresses for each scanning line.

[0021]

[Effects of the Invention] As explained above, the present invention not only performs scrambling by replacing the scanning line signals constituting one frame, but also divides one frame into a plurality of regions and changes the scrambling pattern for each region. Since this double processing is performed, it becomes difficult to decode the secret signal and obtain the image signal, and it is possible to provide an image signal concealment device that can improve the concealment effect of the image signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a transmitting side in an image signal concealment device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a receiving side in an image signal concealment device according to an embodiment of the present invention.

[Explanation of symbols]

1... Transmitting device 2... Receiving device 11... A/D conversion circuit 12... Write address control circuit 13... Odd/even control circuit 14... Odd/even scramble data storage circuit 1
5...Memory circuit 16...Read address control circuit 17...D/A conversion circuit 21...A/D conversion circuit 22...Write address control circuit 23...Memory circuit 24...Read address control circuit 25...Odd/even control circuit 26...Odd・Even descramble data storage circuit 27...D/A conversion circuit

Claims (2)

[Claims] 1. An image signal concealing device for concealing an image signal of one frame composed of a plurality of scanning line signals by changing the transmission order of the scanning line signals when transmitting and receiving the image signal, the transmitting side comprising: a transmitting side area detection means that divides one frame into a plurality of areas in units of scanning lines and detects each area;
a scramble pattern storage means for storing a scramble pattern of a scanning line signal for each region divided by the transmission region detection means; and a scramble pattern storage means for storing a scramble pattern of a scanning line signal for each region divided by the transmission region detection means; scrambling means for changing the transmission order of the scanning line signals according to a scrambling pattern stored in the scrambling pattern; on the receiving side, receiving side area detecting means for detecting each area divided by the sending side area detecting means; descrambling pattern storage means for storing a descrambling pattern for restoring the scanning line signal to the original order for each region divided by the region detection means; and for each region detected by the receiving side region detection means. and a descrambling means for rearranging the scanning line signals to their original order according to the descrambling pattern stored in the descrambling pattern storage means. 2. The image signal concealment device according to claim 1, wherein the transmitting side area detecting means and the receiving side area detecting means include an odd field consisting of odd numbered scanning line signals and an even numbered scanning line signal. 1. An image signal concealment device comprising field detection means for detecting an even field constituted by a scanning line signal.