JP2000217088A - Data superimposing method, data transmission method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data superimposing technology that can identify superimposed data even when processing such as compression of picture data or part of use of a picture is conducted. SOLUTION: A level of emphasis of a picture signal is changed for each frame depending on superimposed data. Or a level of emphasis in a vertical or horizontal direction of the picture signal is changed for each frame depending on the superimposed data. A receiver side detects the level of emphasis for each frame and decodes the superimposed data on the basis of the detected level. Or the receiver side detects the level of emphasis in the vertical and horizontal directions for each fame to detect which direction gives a stronger emphasis level. Then the receiver side decodes the superimposed data on the basis of the detection result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called electronic watermarking technique for superimposing data on an image, and more particularly to a technique for superimposing data using emphasis of an image signal.

[0002]

2. Description of the Related Art In recent years, with the development of digital technology, image data has often been digitized. Digital data has an excellent feature that there is no data deterioration, and no data deterioration occurs when copying data.
Almost the same data as the original is obtained.

Therefore, in digital image data, a problem such as copyright occurs because the duplicated image data has the same quality, and it is necessary to clarify the source of the original data. . Therefore, a technology called electronic watermark has been proposed. This electronic watermark
This is a technique of superimposing data or the like indicating a source on image data so as not to affect the image. As a technology of these electronic watermarks, a technology using spread spectrum, wavelet transform, or the like has been proposed.

[0004]

However, the above-described technique aims at superimposing a large amount of data on one image. Therefore, it is technically complicated, and a device for decoding and encoding data is also complicated and expensive. If the data to be superimposed on one image is small, the cost does not match.

[0005] In addition, digital data is often compressed, but the superimposed data also changes due to the compression, making it difficult to identify the superimposed data in many cases. In particular, in image data, in addition to the above-mentioned compression, processing called enlargement / reduction is also added, so that it is particularly difficult to identify superimposed data.

Further, in the above-described technique, even when image data is converted from digital to analog or from analog to digital, the superimposed data changes, and it is difficult to identify the image data. Therefore, an object of the present invention is to solve the above-described problem, and to superimpose data on an image in a simpler manner and without affecting the image quality of the image when there is little data to be superimposed per image, compared to the prior art. To provide technology.

It is another object of the present invention to provide a data superimposition technique capable of correctly identifying superimposed data even when data is compressed, or when data is converted from digital to analog or from analog to digital. It is in.

[0008]

According to the present invention, there is provided a data superimposing method for superimposing data on an image signal, wherein the data is superimposed on emphasis of the image signal. According to another aspect of the present invention, there is provided a data transmission method for transmitting data by superimposing data in an image signal, wherein the emphasis level of the image signal is changed for each frame in accordance with the data to be superimposed. And transmitting an image signal with data superimposed thereon, receiving the image signal, detecting the level of emphasis for each frame, and decoding the superimposed data from the detected level. It is characterized by the following.

In the step of detecting the level difference, it is also possible to perform a Fourier transform on the image signal and detect the level difference of the emphasis by using the Fourier-transformed signal. According to another aspect of the present invention, there is provided a data transmission method for transmitting data by superimposing data in an image signal, wherein the emphasis level of the image signal is changed for each frame in accordance with the data to be superimposed. Transmitting the image signal with the data superimposed thereon, receiving the image signal, detecting the level difference of the emphasis between the current frame and the previous frame, and superimposing from the change in the level difference. Decoding the data.

In the step of detecting the level difference, it is also possible to perform a Fourier transform on the image signal and detect the level difference of the emphasis using the signal subjected to the Fourier transform. The present invention that achieves the above object is a data transmission method for transmitting data by superimposing data in an image signal, and for each frame, depending on the data to be superimposed, in a vertical direction or in an image signal. Changing one of the levels of emphasis in the horizontal direction, transmitting the image signal on which the data is superimposed, receiving the image signal, and comparing the levels of the emphasis in the vertical direction and the horizontal direction for each frame. And determining whether the level of emphasis in any direction has changed and decoding the data.

In the step of detecting the level difference, it is possible to perform a Fourier transform on the image signal, and to detect the level difference of the emphasis in the vertical direction and the horizontal direction based on the Fourier-transformed signal. The present invention that achieves the above object is a data transmission system,
An encoder that changes the level of emphasis of the image signal for each frame according to the data to be superimposed; and an encoder that receives the image signal, detects the level of emphasis for each frame, and converts the superimposed data from the detected level. And a decoder for decoding.

The encoder includes level adding means for adding the level of emphasis of the image signal, synchronizing means for outputting a synchronizing signal synchronized with one frame based on the image signal, synchronizing with the synchronizing signal, And input control means for controlling the input of the image signal to the level adding means according to the data to be superimposed. Further, the decoder extracts only a contour portion of the image signal and outputs a contour signal indicating the contour, a multiplying unit that multiplies the image signal by the contour signal, and a multiplication unit that outputs an output signal of the multiplying unit. Means for detecting the level, comparing the detected value with a preset threshold value, and decoding the superimposed data based on the comparison result.

Further, the decoder extracts only the contour portion of the image signal and outputs a first contour signal indicating the contour, and multiplies the image signal by the first contour signal. A first multiplying means, a delay means for delaying the image signal by one frame time, and a second contour for extracting only a contour portion of the frame-delayed image signal and outputting a second contour signal indicating the contour. Extracting means; second multiplying means for multiplying the frame-delayed image signal by the second contour signal; output from the first multiplying means;
Difference detection means for detecting a difference from the output of the multiplication means,
And data identification means for identifying superimposed data based on the change in the difference.

The decoder includes a Fourier transform unit for performing a Fourier transform on the image signal, a level of a predetermined frequency of an output signal of the Fourier transform unit, and a detection value and a preset threshold value. And decoding means for decoding the superimposed data based on the comparison result. The decoder includes first Fourier transform means for performing Fourier transform on the image signal, delay means for delaying the output of the Fourier transform means for one frame time, and Fourier transform for the image signal from the delay means. A second Fourier transform unit for performing conversion, a difference detecting unit for detecting a difference between an output of the first Fourier transform unit and an output of the second Fourier transform unit, and superimposing based on a change in the difference. And data identification means for identifying the data being written.

The present invention to achieve the above object is a data transmission system, wherein the level of emphasis in either the vertical direction or the horizontal direction of an image signal is changed for each frame in accordance with data to be superimposed. An encoder and an image signal are received, the level of vertical and horizontal emphasis is detected for each frame, and whether the level of emphasis in the vertical or horizontal direction is changed is detected, and from the detection result, A decoder for identifying the superimposed data.

The encoder includes first level adding means for changing the level of emphasis in the vertical direction,
It comprises a second level adding means for changing the level of the emphasis in the horizontal direction, and a switching means for inputting an image signal to one of the first and second level adding means according to data to be superimposed. be able to. Further, the decoder extracts only a contour portion of the image signal, outputs a contour signal indicating the contour, a multiplying unit that multiplies the image signal by the contour signal, and an output signal of the multiplying unit. Detecting means for detecting the level of horizontal emphasis; detecting means for detecting the level of vertical emphasis from the output signal of the multiplying means;
Based on the detection result of the detection means, it is possible to determine whether the level of emphasis in either the vertical direction or the horizontal direction has been changed, and to identify the superimposed data.

The decoder includes a first Fourier transform unit for performing a Fourier transform on the horizontal direction of the image signal, a second Fourier transform unit for performing a Fourier transform on the vertical direction of the image signal, A difference calculation circuit for calculating a difference between an output of the first Fourier transform means and an output of the second Fourier transform means, and a level of emphasis in either the vertical direction or the horizontal direction based on the difference of the difference calculation circuit Is determined, and identification means for identifying the superimposed data is determined.

[0018]

Embodiments of the present invention will be described.
First, an embodiment of the method of the present invention will be described.
The emphasis emphasizes a certain frequency portion of an image signal (for example, an edge portion of an image). However, even if the level of the emphasis changes, for example, every frame, it cannot be detected by human eyes. Also,
Emphasis is not easily affected by data compression, analog-to-digital conversion, or vice versa. Therefore, the present invention focuses on the feature of the emphasis, and is characterized by superimposing data on the emphasis of the image signal.

In the embodiment of the present invention, an example will be described in which data is superimposed frame by frame on emphasis added to an edge portion of an image. The data to be superimposed here is a digital bit string, for example, "1010 ..."
It is something like The following method is considered as an encoding method for superimposing data on emphasis. (1) As a first encoding method, there is a method of changing the level of emphasis in one frame corresponding to data. For example, if the data to be superimposed is “1”, 1
Raise the level of emphasis in a frame by a predetermined value. On the other hand, when the data to be superimposed is "0", the emphasis level is not changed and the original level is maintained.
This processing is performed for each frame. That is, 1-bit data is superimposed on the basis of the level of emphasis in one frame. FIG. 1 is a conceptual diagram of the first encoding method. In FIG. 1, a thick line portion of the outline of the image indicates that the level of emphasis is increased. (2) As a second encoding method, there is a method of changing the level of emphasis only in the vertical or horizontal direction in one frame in accordance with data. For example, when the data to be superimposed is “1”, the level of the emphasis in the vertical direction is increased by a predetermined value, and the level of the emphasis in the horizontal direction is maintained. On the other hand, when the data to be superimposed is "0", the level of the emphasis in the horizontal direction is increased by a predetermined value, and the level of the emphasis in the vertical direction is maintained. This processing is performed for each frame. That is, 1-bit data is superimposed on the vertical or horizontal level of emphasis in one frame. FIG. 2 is a conceptual diagram of the second method. In FIG. 2, a thick line portion of the outline of the image indicates that the level of emphasis is increased.

Next, a method of decoding data from an image signal on which data is superimposed by the first encoding method or the second encoding method will be described. First, as a method of decoding an image signal encoded by the first encoding method, the following method can be considered. (1) The first decoding method utilizes the fact that the level of emphasis before superimposing data hardly changes between consecutive frames. That is, data is decoded by simply detecting the level of emphasis for each frame and comparing the level with a predetermined threshold. For example, when the level of the detected emphasis is higher than a predetermined threshold value, it is determined that the data is “1”. On the other hand, when the detected emphasis level is lower than a predetermined threshold value, it is determined that the data is “0”. (2) The second decoding method is a method of obtaining a difference in emphasis between frames. For example, the difference between the emphasis of the previous and next frames is obtained. If the difference is 0, it is determined that the same data is continuous. If the difference is in the plus / minus direction, the data is determined at that time. For example, when the data is “1110001...”, The difference is 0 for the data “111”, and at this time, it cannot be determined whether the data is “1” or “0”. It is only understood that the same data is continuous. However, when the data changes from "1" to different data such as "0", the difference becomes a numerical value other than 0. For example, when the data changes from “1” to “0”, the level of the emphasis changes from High to Low, so the difference becomes a negative value (when the emphasis level of the previous frame is subtracted from the emphasis level of the current frame) ).
Therefore, if the difference changes to minus,
Since the data changes from "1" to "0", it can be seen that the continuous data is "1", while if the data changes from "0" to "1", the emphasis level is Lo.
Since the value changes from w to High, the difference is a positive value (when the emphasis level of the previous frame is subtracted from the emphasis level of the current frame). Therefore, when the difference changes to plus, it means that the data changes from "0" to "1", and it is understood that the continuous data is "0".

(3) The third decoding method is an application of the first and second decoding methods, and is characterized by using a Fourier transform for decoding. Since the frequency components of a normal image are substantially equal, if the image signal on which the data is superimposed is subjected to Fourier transform, the level of the frequency component in the portion on which the data is superimposed increases. Utilizing this, it is easy to detect the level of a portion where data is superimposed.

The subsequent processing is the same as the first and second decoding methods already described. That is, as a method corresponding to the first decoding method, the image signal is Fourier-transformed for the entire screen (vertical direction and horizontal direction) for each frame, the level of the signal is detected, and this level is set to a predetermined level. The data is decoded by comparing with the threshold value of. In addition, as equivalent to the second decoding, a difference between the signal of the previous frame subjected to the Fourier transform and the signal of the current frame subjected to the Fourier transform is obtained, and the signal is decoded based on the difference.

Next, a method of decoding an image signal on which data is superimposed by the second encoding method will be described. As a decoding method corresponding to the second encoding method, a vertical emphasis level and a horizontal emphasis level are detected for each frame. Then, it detects which of the emphasis levels is higher, and decodes the data. At this time, the above-described Fourier transform may be used. That is, the image signal is Fourier-transformed separately in the horizontal and vertical directions, the signal level in the vertical direction and the signal level in the horizontal direction are detected, and the superimposed data is decoded depending on which signal level is higher. The average level in the vertical and horizontal directions and the total sum level in the vertical and horizontal directions can be used as the signals to be compared at this time.

Next, an embodiment of the invention of a system for realizing the above-described data transmission method will be described. First, an encoder based on the first encoding method will be described. FIG. 3 is a block diagram of the encoder according to the present embodiment. FIG.
Among them, 1 is an input terminal to which an image signal to which emphasis is added is input, and 2 is an input terminal to which a data signal is input.

Reference numeral 3 denotes a vertical / horizontal digital filter. The vertical / horizontal digital filter 3 is a filter for controlling the level of emphasis at the edge portion of the image signal based on the superimposed data. Reference numeral 4 denotes a synchronization circuit. The synchronization circuit 4 is a circuit that outputs a synchronization signal for each frame based on an image signal.

Reference numeral 5 denotes a bypass control circuit. The bypass control circuit 4 controls the vertical / horizontal digital filter 3 based on the synchronization signal from the synchronization circuit 4 and the input data signal. That is, the end of the frame is known from the synchronization signal. When the data signal is "1", the image signal is processed by the vertical / horizontal digital filter 3, and when the data signal is "0", the image signal is processed vertically / horizontally. It is bypassed from the digital filter 3.

Here, the vertical / horizontal digital filter 3
Will be described in more detail. FIG. 4 is a block diagram of the vertical / horizontal digital filter 3. As shown in FIG. 4, the vertical / horizontal digital filter 3 is configured by connecting a 5-tap digital filter in series. The digital filter at the preceding stage is for vertical, and the digital filter at the latter stage is for horizontal.

Taps T1 to T1 of the vertical digital filter
The tap coefficients of T5 are −1/8, 0, 9/8, 0, −1
/ 8, and each of the delay circuits 31 to 34 delays the input image signal by one line and outputs it. Then, the delayed image signal is input to each of the taps T1 to T5. The tap coefficients of the taps T1 to T5 of the horizontal digital filter are as follows:
−1/8, 0, 9/8, 0, −1/8, and each of the delay circuits 35 to 38 delays the input image signal by one pixel and outputs it. Then, the image signals delayed by the delay circuits D1 to D5 are input to the taps T1 to T5.

As described above, the level of emphasis in the vertical direction is increased by the digital filter of the preceding stage, and the level of emphasis in the horizontal direction is increased by the digital filter of the subsequent stage. The switch 30 switches the switch based on the control signal of the bypass control circuit 5 to bypass the digital filter.

Subsequently, according to the first encoding method,
A decoder for decoding data superimposed on an image signal will be described. First, a decoder corresponding to the first decoding method will be described. FIG. 5 is a block diagram of the decoder. In FIG. 5, reference numeral 51 denotes an input terminal to which an image signal on which data is superimposed is input.

Reference numeral 52 denotes a contour extraction circuit. The contour extraction circuit 52 outputs a signal indicating the contour (edge portion) of the image among the input image signals. 53 is a multiplier.
The multiplier 53 multiplies the output of the contour extraction circuit 52 by the image signal. That is, the image signal from the input terminal 51 is multiplied by the signal indicating the edge portion. As a result, the multiplier 53 outputs only the signal of the edge portion to which emphasis is added.

Reference numeral 54 denotes a level detection circuit. The level detection circuit 54 detects the level of the output signal of the multiplier 53, and outputs a data signal "1" if the level is equal to or greater than a certain threshold. If the level is equal to or less than the threshold value, a data signal "0" is output. Next, the operation of the system configured as described above will be described. First, an image signal is input from the input terminal 1. On the other hand, bit data “100110010...” Is input from the input terminal 2.

The synchronizing circuit 4 outputs a synchronizing signal for each frame to the bypass control circuit 5 based on the image signal inputted from the input terminal 1. The bypass control circuit 5 outputs a bypass control signal based on the bit data input from the input terminal 2. The timing is output at the start timing of one frame based on the synchronization signal.
For example, if the data is "1", a control signal for processing the image signal by the vertical / horizontal digital filter 3 is output at the beginning of the frame. If the data is "0", the image signal is output to the vertical / horizontal digital filter 3. And outputs a control signal to be bypassed at the head timing of the frame.

In the vertical / horizontal digital filter 3, if the bypass control signal indicates a process, a process of adding (raising) the level of the emphasis of the input image signal is performed. If the bypass control signal indicates bypass, the digital filter is bypassed by the switch 30 and output. The vertical / horizontal digital filter 3 outputs an image signal on which data is superimposed.

On the other hand, in the decoder which has received the image signal on which the data is superimposed, the image signal is input to the contour extraction circuit 52. Then, the contour extraction circuit 52 outputs a signal indicating only the contour portion. The multiplier 53 multiplies the image signal by the output of the contour extraction circuit 52 to output a signal of an edge portion to which emphasis is added. The output of the multiplier 53 is input to the level detection circuit 54, where the level of emphasis is detected. The detected level of emphasis is compared with a set threshold. here,
The threshold value set in the level detection circuit 54 is a value slightly lower than the value obtained by adding the level of emphasis and the level added by the vertical / horizontal digital filter 3. When the detected emphasis level is higher than the threshold value, the data signal “1” is output, and when the detected emphasis level is lower than the threshold value, the data signal “0” is output.

Next, a decoder corresponding to the second decoding method will be described. FIG. 6 is a block diagram of the decoder. In FIG. 6, reference numeral 61 denotes an input terminal to which an image signal on which data is superimposed is input. 62 is a first contour extraction circuit, and 63 is a second contour extraction circuit. These contour extraction circuits 62 and 63 output signals indicating the contour (edge portion) of the image among the input image signals.

Reference numeral 64 denotes a frame delay circuit for delaying an input image signal by one frame. 65
Is a first multiplier, and 66 is a second multiplier. These multipliers 65 and 66 multiply the outputs of the contour extraction circuits 62 and 63 by the image signals. That is, the signal indicating the edge portion is multiplied by the image signal from the input terminal 2. As a result, multipliers 65 and 66 output signals at the edge portions to which emphasis has been added.

Reference numeral 67 denotes a difference detection circuit. The difference detection circuit 67 calculates the difference between the signals of the multipliers 65 and 66 (multiplier 6
5—the output of the multiplier 66). 68
Is a data identification circuit. This data identification circuit 68
The superimposed data is identified from the output (difference) of the difference detection circuit 67. That is, if the difference is 0, it is determined that the same data is continuous, and the data is determined when the difference changes in the plus or minus direction. For example, if the data is "1110001 ...", the data "1
11 ", the difference is 0, and at this point, the data is"
It cannot be determined whether it is 1 "or" 0 ". It can be seen that the same data is continuous, but when the data changes from" 1 "to different data such as" 0 ", The difference is a numerical value other than 0. For example, data "
If the value changes from 1 "to" 0 ", the difference becomes a negative value. If the difference changes to a negative value, the data becomes" 1 ".
Since this is the case where the data changes from "0" to "0", it is understood that the continuous data is "1". On the other hand, data "0" to "
When the difference changes to "1", the difference is a positive value. Therefore, when the difference changes to a positive value, the data changes from "0" to "1". I understand that there is.

Next, an encoder and a decoder corresponding to the second encoding method and the decoding method will be described. FIG. 7 is a block diagram of an encoder corresponding to the second encoding method. In FIG. 7, reference numeral 71 denotes an input terminal to which an image signal to which emphasis is added is input, and reference numeral 72 denotes an input terminal to which a data signal is input.

Reference numeral 73 denotes a vertical digital filter. The vertical digital filter 73 is a filter for increasing the level of emphasis in the vertical direction among emphasis of the image signal. A detailed block diagram of the vertical digital filter 73 is shown in FIG. Digital filter 73 for vertical
Tap coefficients of taps T1 to T5 are −1/8, 0, 9
/ 8, 0, −1/8, and the delay circuits 100 to 104
Outputs the input image signal with one line delay. The delayed image signal is input to each of the taps T1 to T5,
Each tap is multiplied by a tap coefficient. The outputs of the taps are added by the adder 105 and output.

Reference numeral 74 denotes a horizontal digital filter. The horizontal digital filter 74 is a filter for increasing the level of the emphasis in the horizontal direction among the emphasis of the image signal. A detailed block diagram of the horizontal digital filter 74 is shown in FIG. Horizontal digital filter 74
Tap coefficients of taps T1 to T5 are −1/8, 0, 9
/ 8, 0, −1/8, and the delay circuits 110 to 114
Outputs an input image signal with a delay of one pixel. The delayed image signal is input to each of the taps T1 to T5, and each tap is multiplied by a tap coefficient. The outputs of the taps are added by the adder 115 and output.

Reference numeral 75 denotes a synchronization circuit. This synchronous circuit 75
Is a circuit that outputs a synchronization signal for each frame based on an image signal. 76 is a switch control circuit. The switch control circuit 76 controls the vertical digital filter 73 and the horizontal digital filter 74 of the image signal based on the synchronization signal from the synchronization circuit 75 and the input data signal.
Control the input to. That is, the end of the frame is known from the synchronization signal. When the data signal is "1", the image signal is input to the vertical digital filter 73. When the data signal is "0", the image signal is input to the horizontal digital filter 74. Input.

Next, the decoder will be described. FIG.
0 is a block diagram of the decoder. In FIG. 10, reference numeral 81 denotes an input terminal to which an image signal on which data is superimposed is input. 82 is a contour extraction circuit. This contour extraction circuit 82
Is the outline (edge part) of the image in the input image signal
Is output.

Reference numeral 83 denotes a multiplier. This multiplier 83
The output of the contour extraction circuit 82 is multiplied by the image signal. That is, the signal indicating the edge portion and the input terminal 81
Is multiplied by the image signal. As a result, the signal of the edge portion to which emphasis is added is output from the multiplier 83. Reference numeral 84 denotes a 5-pixel extraction circuit. The five-pixel extraction circuit 84 extracts five consecutive pixels in the horizontal direction from the output of the multiplier 83 and detects the level of emphasis of each signal. If the emphasis levels of the five pixels are all equal to or greater than a predetermined threshold, a counter 87 described later
To output a counter pulse. On the other hand, if at least one of the emphasis levels is equal to or less than the threshold, no counter pulse is output.

Reference numeral 85 denotes a 5-line extraction circuit. The five-line extraction circuit 85 extracts five consecutive pixels in the vertical direction from the output of the multiplier 83 and detects the level of emphasis of each signal. If all the emphasis levels of the five pixels are equal to or greater than a predetermined threshold value, a counter pulse is output to a counter 88 described later. On the other hand, if at least one of the emphasis levels is equal to or less than the threshold, no counter pulse is output.

Reference numeral 86 denotes a synchronization circuit. This synchronization circuit 86
Is a circuit that outputs a synchronization signal for each frame based on an image signal. 87 is a first counter. The counter 87 counts up one by one counter pulse of the five-pixel extraction circuit 84. Then, the counter value is output and reset by the synchronization signal from the synchronization circuit 86.

Reference numeral 88 denotes a second counter. Counter 8
8 increments the counter by one by one counter pulse of the five-line extraction circuit 85. And the synchronization circuit 8
The counter value is output and the counter value is reset to zero by the synchronization signal from 6. 89 is a comparison circuit. The comparison circuit 89 compares the counter values of the counters 87 and 88. Then, a data signal is output according to the comparison result. That is, when the counter value of the counter 87 is larger, it is determined that the level of the emphasis in the horizontal direction is higher, and the data signal “0” is output. Also, counter 8
If the counter value of 8 is larger, it is determined that the level of emphasis in the vertical direction is higher, and the data signal "1" is output.

Next, the operation of the system configured as described above will be described. First, an image signal is input from the input terminal 71. On the other hand, bit data "1" is input from the input terminal 72.
. 00110010... Are input.
Then, a synchronization signal for each frame is output to the switch control circuit 76 based on the image signal input from the input terminal 71.

The switch control circuit 76 switches the switch 77 based on the bit data input from the input terminal 72. Its timing is 1 based on the synchronization signal.
Output at the start timing of the frame. For example, if the data is "1", the switch 77 is switched to the vertical digital filter 73, and the image signal is input to the vertical digital filter 73. If the data is "0", the switch 77 is switched to the horizontal digital filter 74, and the image signal is input to the horizontal digital filter 74.

The vertical digital filter 73 and the vertical digital filter 74 perform processing for adding (raising) the level of emphasis of the input image signal. The vertical digital filter 73 and the vertical digital filter 74 output image signals on which data is superimposed. On the other hand, in the decoder that has received the image signal on which the data is superimposed, the image signal is input to the contour extraction circuit 82. Then, the contour extraction circuit 82 outputs a signal indicating only the contour portion. The multiplier 83 multiplies the image signal by the output of the contour extraction circuit 82 to output an edge signal to which emphasis is added.

The output of the multiplier 83 is input to a five-pixel extraction circuit 84, and the level of emphasis of five pixels that are continuous in the horizontal direction is detected. If the emphasis level of all five pixels is equal to or higher than a predetermined threshold value, a counter pulse
7 is output. Similarly, the output of the multiplier 83 is also input to the five-line extraction circuit 85, and the level of emphasis of five consecutive pixels in the vertical direction is detected. If the level of emphasis is equal to or greater than a predetermined threshold value for all five pixels, a counter pulse is output to the counter 88. These processes are performed for one frame.

The counters 87 and 88 receive the counter pulse and count up the count value one by one. Then, the count value is output to the comparison circuit 89 by the synchronization signal from the synchronization circuit 86, and the count value is returned to zero. The comparison circuit compares the count values and outputs a data signal corresponding to the larger count value. For example, when the counter value of the counter 87 is larger, it is determined that the level of the emphasis in the horizontal direction is higher, and the data signal “0” is output.
Is output. If the counter value of the counter 88 is larger, it is determined that the level of the vertical emphasis is high, and the data signal “1” is output.

Next, decoding using Fourier transform will be described. Note that a decoder using the Fourier transform is:
The use of the Fourier transform differs from the decoder described above. Therefore, detailed description of the other parts is omitted. First, a decoder that detects and decodes a signal level for each frame in the first encoding method will be described.

FIG. 11 is a block diagram of the decoder. In FIG. 11, reference numeral 91 denotes an input terminal to which an image signal on which data is superimposed is input. Reference numeral 92 denotes an FFT (Fast Fourier Transform) for performing a Fourier transform on an input image signal.
Circuit. 93 is a level detection circuit. The level detection circuit 93 detects the level of a portion corresponding to the frequency of emphasis in the output signal of the FFT circuit 92,
If the level is equal to or higher than a certain threshold, a data signal "1" is output. If the level is below the threshold, the data signal
0 "is output. The set threshold value is set to a value slightly lower than the signal level when a normal image signal is Fourier-transformed.

Next, a decoder for decoding using the frame difference will be described. In FIG. 12, reference numeral 100 denotes an input terminal to which an image signal on which data is superimposed is input.
101 is a first FFT circuit, and 102 is a second FFT circuit.
This is a T circuit. These FFT circuits 101 and 102 are circuits that perform Fourier transform on the input image signal in the vertical and horizontal directions. The FFT circuit 102 receives an image signal delayed by one frame by a frame delay circuit 103 described later.

Reference numeral 103 denotes a frame delay circuit for delaying an input image signal by one frame. 1
04 is a difference detection circuit. This difference detection circuit 104
Calculates the difference between the output of the FFT circuit 101 and the output of the FFT circuit 102 (the output of the FFT circuit 101-the output of the FFT circuit 102) and outputs the result. Since the level of the current frame and the level of the previous frame are usually almost the same, a difference between them is that a frequency component of enhanced emphasis is output.

Reference numeral 105 denotes a data identification circuit. The data identification circuit 105 identifies the superimposed data from the output (difference) of the difference detection circuit 104. That is,
If the difference is 0, it is determined that the same data is continuous,
Then, when the difference changes in the plus / minus direction, the data is determined. For example, if the data is "1110001"
.. ", The difference is 0 for the data" 111 ", and at this point, it cannot be determined whether the data is" 1 "or" 0 ".It is only understood that the same data is continuous. However, when the data changes from "1" to different data, such as "0", the difference is a numerical value other than 0. For example, when the data changes from "1" to "0", the difference is a negative value When the difference changes to minus, it means that the data changes from "1" to "0", so it can be understood that continuous data is "1".
When the data changes from "0" to "1", the difference becomes a positive value. Therefore, when the difference changes to plus, it means that the data changes from "0" to "1", and it can be understood that continuous data is "0".

Next, a decoder for decoding data encoded by the second encoder method will be described. FIG. 13 is a block diagram of the decoder. FIG.
Reference numeral 200 denotes an input terminal to which an image signal on which data is superimposed is input.

Reference numeral 201 denotes a first FFT circuit. This F
The FT circuit 201 is a circuit that performs a Fourier transform on the input image signal in the horizontal direction. Then, the average level of the horizontal line is calculated and output. 202 is the second FF
This is a T circuit. The FFT circuit 202 is a circuit that performs a Fourier transform on a vertical direction of an input image signal. Then, the average level of the vertical line is calculated and output.

Reference numeral 203 denotes a difference detection circuit. The difference detection circuit 203 calculates and outputs the difference between the output of the FFT circuit 201 and the output of the FFT circuit 202 (the output of the FFT circuit 201-the output of the FFT circuit 202). Since the signal levels are usually almost the same in the same frame, the difference is to output a frequency component of enhanced emphasis.

Reference numeral 204 denotes a data identification circuit. The data identification circuit 204 receives the difference output of the difference detection circuit 204, and when the difference is plus, the level of the emphasis in the horizontal direction is raised, and the superimposed data is “
0, and outputs a data signal "0" .If the difference is negative, the level of emphasis in the vertical direction is increased, and the superimposed data is determined to be "1" and the data is determined to be "1". Outputs signal "1".

In this decoder, the average level of the signal is used for the level detection, but a total sum of the signal levels may be used.

[0063]

According to the present invention, data can be superimposed on an image by a simple method without deteriorating the quality of the image. Further, according to the present invention, it is possible to provide a data superimposition technique that can withstand data compression, analog-to-digital conversion, and digital-to-analog conversion.

Further, according to the present invention, it is possible to identify the superimposed data even when performing processing such as partial use of an image.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a data superposition method according to the present invention.

FIG. 2 is a diagram for explaining a data superposition method of the present invention.

FIG. 3 is a block diagram of an encoder according to the present embodiment.

FIG. 4 is a block diagram of the vertical / horizontal digital filter 3. FIG.

FIG. 5 is a block diagram of a decoder.

FIG. 6 is a block diagram of a decoder.

FIG. 7 is a block diagram of an encoder corresponding to a second encoding method.

FIG. 8 is a block diagram of a vertical digital filter 73.

FIG. 9 is a block diagram of a horizontal digital filter 74.

FIG. 10 is a block diagram of a decoder corresponding to a second decoding method.

FIG. 11 is a block diagram of a decoder.

FIG. 12 is a block diagram of a decoder.

FIG. 11 is a block diagram of a decoder.

[Description of Signs] 3 Vertical / horizontal digital filter 4, 75, 80 Synchronization circuit 5 Bypass control circuit 52, 62, 63, 82 Contour extraction circuit 53, 65, 66, 83 Multiplier 54 Level detection circuit 64 Frame delay circuit 67 , 104, 203 Difference detection circuit 68, 105, 204 Data identification circuit 73 Vertical digital filter 74 Horizontal digital filter 76 Switch control circuit 84 Five-pixel extraction circuit 85 Five-line extraction circuit 87, 88 Counter 89 Comparison circuit 92, 101, 102, 201, 202 FFT circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Kimura 1-1-1 Nishiasakusa, Taito-ku, Tokyo F-term in Next Generation Information and Broadcasting System Research Laboratories 5C063 AB03 AB05 CA14 CA23 CA40 5C076 AA40 5K028 EE03 SS04 SS14

Claims (17)

[Claims] 1. A data superimposing method for superimposing data on an image signal, wherein the data is superimposed on emphasis of the image signal. 2. A data transmission method for transmitting data by superimposing data on an image signal, the method comprising: changing an emphasis level of an image signal for each frame according to data to be superimposed; Transmitting the superimposed image signal; receiving the image signal, detecting the level of emphasis for each frame, and decoding the superimposed data from the detected level. Transmission method. 3. The data transmission according to claim 2, wherein in the step of detecting the level difference, a Fourier transform is performed on the image signal, and a level difference of emphasis is detected using the Fourier-transformed signal. Method. 4. A data transmission method for transmitting data by superimposing data in an image signal, the method comprising: changing an emphasis level of an image signal for each frame in accordance with the data to be superimposed; Transmitting the superimposed image signal, receiving the image signal, detecting a level difference in emphasis between the current frame and the previous frame, and decoding the superimposed data from the change in the level difference. A data transmission method comprising: 5. The data transmission according to claim 4, wherein in the step of detecting the level difference, a Fourier transform is performed on the image signal, and a level difference of emphasis is detected using the Fourier-transformed signal. Method. 6. A data transmission method for transmitting data by superimposing data in an image signal, wherein one of the vertical direction and the horizontal direction in the image signal is performed for each frame according to the data to be superimposed. Changing the level of emphasis of the image, transmitting the image signal on which the data is superimposed, receiving the image signal, comparing the level of the emphasis in the vertical direction and the level of the horizontal direction for each frame, and Determining whether the level of emphasis has changed, and decoding the data. 7. The step of detecting a level difference, wherein a Fourier transform is performed on the image signal, and a level difference between vertical and horizontal emphasis is detected based on the Fourier-transformed signal. Item 6. The data transmission method according to Item 6. 8. A data transmission system, comprising: an encoder for changing an emphasis level of an image signal for each frame according to data to be superimposed; receiving an image signal and detecting an emphasis level for each frame. And a decoder for decoding data superimposed from the detected level. 9. An encoder, comprising: a level adding unit for adding an emphasis level of an image signal; a synchronizing unit for outputting a synchronizing signal synchronized with one frame based on the image signal; 9. The data transmission system according to claim 8, further comprising input control means for controlling input of an image signal to said level adding means according to data to be superimposed. 10. The decoder according to claim 1, wherein the decoder extracts only a contour portion of the image signal, and outputs a contour signal indicating the contour; a multiplying unit that multiplies the image signal by the contour signal; 9. The apparatus according to claim 8, further comprising: means for detecting the level of the output signal, comparing the detected value with a preset threshold value, and decoding the superimposed data based on the comparison result. Data transmission system. 11. The decoder according to claim 1, wherein the decoder extracts only an outline portion of the image signal and outputs a first outline signal indicating the outline, and multiplies the image signal by the first outline signal. A first multiplying unit that performs a delay of one frame time on the image signal, and a second contour that extracts only a contour portion of the frame-delayed image signal and outputs a second contour signal indicating the contour. Extraction means; second multiplication means for multiplying the frame-delayed image signal by the second contour signal; and a difference between an output of the first multiplication means and an output of the second multiplication means. 9. The data transmission system according to claim 8, further comprising: a difference detecting means for detecting; and a data identifying means for identifying superimposed data based on a change in the difference. 12. The decoder, comprising: a Fourier transform unit for performing a Fourier transform on the image signal; detecting a level of a predetermined frequency of an output signal from the Fourier transform unit; And means for decoding the superimposed data based on the comparison result.
Data transmission system. 13. The image processing apparatus according to claim 1, wherein the decoder performs a Fourier transform on the image signal, a first Fourier transform unit, a delay unit that delays an output of the Fourier transform unit by one frame time, and an image signal from the delay unit. Second Fourier transform means for performing a Fourier transform on the input signal; a difference detecting means for detecting a difference between an output of the first Fourier transform means and an output of the second Fourier transform means; 9. The data transmission system according to claim 8, further comprising data identification means for identifying the superimposed data. 14. A data transmission system, comprising: an encoder for changing an emphasis level of only one of a vertical direction and a horizontal direction of an image signal for each frame in accordance with data to be superimposed; Detecting the level of emphasis in the vertical and horizontal directions for each frame, detecting whether the level of emphasis in the vertical or horizontal direction has been changed, and identifying the superimposed data from the detection result. A data transmission system, comprising: 15. The encoder according to claim 1, wherein: the first level adding means for changing the level of the emphasis in the vertical direction; the second level adding means for changing the level of the emphasis in the horizontal direction; 15. The data transmission system according to claim 14, further comprising switching means for inputting an image signal to one of said first and second level adding means. 16. The decoder according to claim 1, wherein the decoder extracts only a contour portion of the image signal and outputs a contour signal indicating the contour; a multiplying unit that multiplies the image signal by the contour signal; Detecting means for detecting the level of emphasis in the horizontal direction from the output signal; detecting means for detecting the level of emphasis in the vertical direction from the output signal of the multiplying means; and 15. The data transmission system according to claim 14, further comprising: identification means for judging whether the level of emphasis in any one of the directions is changed, and identifying the superimposed data. 17. The image processing apparatus, comprising: a first Fourier transform unit for performing a Fourier transform on a horizontal direction of an image signal; a second Fourier transform unit for performing a Fourier transform on a vertical direction of the image signal; A difference calculating circuit for calculating a difference between an output of the first Fourier transforming means and an output of the second Fourier transforming means; 15. A data transmission system according to claim 14, further comprising identification means for judging whether or not the data has been changed, and identifying the superimposed data.