JPH06118927A - Secrecy keeping device for visual information - Google Patents

Abstract

PURPOSE:To provide the secrecy keeping device for visual information which prevents display information from being known except to an operator. CONSTITUTION:This device consists of an information input part 1 for inputting information to be kept secret, a complementary color arithmetic part 2 for generating a complementary color image in complementary color relation with the image when the input information is displayed, a time division part 3 which displays the input image and complementary color image on a time-division basis, an image output part 4 for making a time-division display of the input image and complementary color image, which are sent on a time-division basis, a polarized light switching part 5 which switches polarized light, a synchronization control part 6 which synchronizes the time division of the image with the switching of the polarized light, and a polarizing filter 7 which is provided on the operator's side so as to extract the input image from the time-division display image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual information concealing device for concealing visual information to a person other than an operator when visually displaying information.

[0002]

2. Description of the Related Art The frequency of exchanging information using computers and networks such as electronic mail is increasing. In e-mail and electronic bulletin boards, confidentiality is aimed at by limiting the number of people who can browse or by encrypting. However, when decrypted and displayed on the screen, there is the problem that anyone can look into it.

The invention disclosed in Japanese Patent Application Laid-Open No. 63-170681 is related to the security of the display screen for solving this problem. The present invention relates to a display for displaying information by utilizing a partial polarization phenomenon, in which a first electronic polarizing plate placed on the display side, a second electronic polarizing plate placed on the observer side, and a first electronic polarizing plate It is a display for a personal terminal, which has means for synchronously changing the electronic polarizing plate and the second electronic polarizing plate. This changes the polarization plane of the information displayed on the display according to a predetermined rule and synchronizes the electronic polarization filter attached to the operator's glasses with the change of the polarization plane so that only the operator can see the information. It is a device that does.

However, with such a conventional apparatus, a noise-like image can be seen by people other than the operator, and the display information can be inferred from this noise-like image. Therefore, complete confidentiality of information has not been realized.

[0005]

As described above, in the conventional apparatus, the image related to the display information is always displayed without being erased, and there is a problem that a person other than the operator can guess the display information.

In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a visual information concealing device which prevents anyone other than the operator from knowing the display information.

[0007]

According to the present invention, an information input section for inputting information to be concealed and a complementary color image having a complementary color relationship with the display image of the information input by the information input section are generated. A complementary color calculation unit, a time division unit for displaying the complementary color image generated by the complementary color calculation unit and the display image in a time division manner, the display image sent in a time division manner by the time division unit, and the An image output unit for time-divisionally displaying the complementary color image, a polarization switching unit for switching the polarization in synchronization with the time-division timing in the time-division unit,
There is provided a visual information concealment device including a polarization filter provided on the observer side for extracting the display image from an image displayed in time division according to the time division timing of the polarization switching unit.

[0008]

The complementary color calculation unit generates an image having a complementary color relationship with the target image, displays the complementary color image and the original image on the display in a time division manner, and the polarization switching unit synchronized with the time division is displayed on the display unit. Since it is placed between the operator and the operator and the image information is extracted by the polarized glasses, a person other than the operator can see only the image in which the generated complementary color image and the original image cancel each other. The display information can be completely hidden.

[0009]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a block diagram of a visual information hiding device according to an embodiment of the present invention.

The target image is a still image, a moving image, a real image, a CG image, or an image in which characters or figures are developed into a display image, and the image input unit 1 is a device capable of capturing these images, for example, a scanner, A video camera, a keyboard, etc. Similarly, the image output unit 4 also uses a device capable of outputting these images, such as a CRT or a liquid crystal display.

The image captured by the image input unit 1 is the original image. The original image data is color data composed of red, green, and blue with the pixel on the output screen as a minimum unit. The original image data is input to the complementary color calculation unit 2, and the complementary color calculation unit 2 performs arithmetic processing on the original image data to newly generate a complementary color image for the original image. The original image and the complementary color image data are input to the time division unit 3 and prepared.
Stored in one frame buffer respectively. Further, in the time division unit 3, two frame buffers are alternately selected to switch between the original image and the complementary color image. The switching cycle at this time is, for example, 1/60 second, or 1/12.
It is a short cycle such as 0 seconds.

The original image or the complementary color image selected by the time division unit 3 is output to the image output unit 4, for example, a CRT.
4a is displayed. Therefore, the observer can see C of the image output unit 4.
The series of images that can be viewed through the RT 4a are a composite image in which the original image and the complementary color image are alternately displayed in a short cycle, so that both images cancel each other.

That is, as shown in FIG. 2, the original image 8
By displaying the complementary color image 10 on the CRT 4a in a time-division manner, the image that can be viewed by the observer becomes a composite image 12 that is a combination of the original image and the complementary color image. In this example, the triangle 9 is a secret object, and when the complementary color calculation is performed on the entire original image 8, the canceled composite image 12 is the original image 8.
The image is filled with a composite color that is a combination of the original color and its complementary color. Therefore, the display information of the original image 8 cannot be inferred from this composite image 12.

Therefore, by utilizing the polarization phenomenon, the display information is extracted so that only the operator can see the original image. In this case, first, the image output from the image output unit 4 is passed through the polarization switching unit 5. For the polarization switching unit 5, for example, a liquid crystal shutter that switches the direction of rotation of circularly polarized light is used. The polarization switching in the polarization switching unit 5 is synchronized with the image switching in the time division unit 3. Therefore, a synchronization control unit 6 is provided between the polarization switching unit 5 and the time division unit 3 to perform synchronization control. That is, this synchronization control unit 6
The polarization switching unit 5 is synchronously controlled so that a fixed polarization is always selected for each of the original image and the complementary color image. For example, in the case of circularly polarized light, right-handed circularly polarized light is made to correspond to the original image, and left-handed circularly polarized light is made to correspond to the complementary color image.

Further, in order to extract only the original image, a polarization filter 7 that allows only the polarized light synchronized with the original image to pass through in the polarization switching unit 5 is provided on the operator side. By wearing such polarizing filter 7 as polarizing glasses, the operator can see the display information of the original image without being known to anyone other than the operator. That is, a person without polarized glasses is presented with the composite image 12 shown in FIG. 2, and an observer wearing polarized glasses is presented with the original image 8. Since the number of operators is not limited to one, in such a case, it is necessary to prepare a plurality of the same polarized glasses or a polarizing plate that only the operator can look through.

In FIG. 1, the polarization switching unit 5 arranged between the image output unit 4 and the polarization filter 7 is the image output unit 4
May be attached to the polarizing filter 7 or the polarizing filter 7. In both cases, when the image is viewed without passing through the polarization filter 7, only the image filled with the composite color in which the original color and the complementary color are composited can be seen.

FIG. 3 is a flowchart showing an example of complementary color calculation performed by the complementary color calculation unit 2.

The original image is divided into pixels on the screen, and each pixel is represented by a subscript i, j. Further, each pixel is composed of three colors (RGB) of red, green, and blue, and each color is set at a brightness level of 256. If the RGB value of each pixel on the screen is represented by Cij = (R, G, B) and each component takes a value of 0 to 255, 16777216 of black to white
Can represent different types of colors.

The complementary color calculation is performed for each pixel by using the original color Cij.
Is an operation for obtaining the complementary color C * ij with the input data. Here, the complementary color calculation is performed for all pixels.

RGB which is a complementary color to the input data Cij
Generally, the value is C * ij (R *, G *, B *).
Can be expressed by C * ij = f (Cij) as a function of Cij. Here is the simplest formula to find C * ij,
Consider (Cij + C * ij-N) / 2 = A. However, A = (AR, AG, AB) and each component is 0 to 2
It can take a value of 55. Then, with this A, it is possible to specify a composite color formed by mixing the original color and the complementary color. Further, it is considered that N = (1,1,1) and the component includes 0.

Now, assuming that A = (127, 127, 127), the equation C * ij = F-Cij can be obtained from the above equation.
However, F = (255, 255, 255). With this equation, complementary color calculation can be easily performed.

For example, if black (0,0,0) is input as the original color, white (255,25) is input as its complementary color.
5, 255) is output. From these two colors, gray (12
7, 127, 127) are synthesized. Thus, when the original color Cij is determined, the complementary color C * ij is uniquely determined.

By changing A, the color when the original color and the complementary color are superposed can be selected, but A limits the original color Cij that can be used as input data. Therefore, the output complementary color C * ij also has a limited value.

FIG. 4 is a graph showing possible values of Cij and C * ij in a certain A. However, the color value is represented by 0.0 to 1.0, and 0.0 is (0,0,0).
In addition, 1.0 corresponds to (255, 255, 255). Also, the graph is drawn continuously rather than discretely.

When A = 0.2 (a), Cij and C
The range of possible values of * ij is 0.1 to 0.4. A =
In the case of 0.5 (b), the range of possible values is 0.0-1.
It can take the whole range of 0. This is the previous A = (1
27, 127, 127). A =
In the case of 0.8 (c), the possible range is 0.5 to 1.0.

As described above, since Cij that can be handled depends on A, it is practical to select 0.5 as A when there are a wide variety of input colors, such as when the original image is a photographed image. Target.

Since this composite color A can be changed within a certain range, if the value of A is changed with time, information other than the displayed information is shown to a person other than the operator and disturbed to cause the original information to be disturbed. The confidentiality can be enhanced.

The complementary color calculation may be performed for all the pixels on the screen as described above, but may be performed for only a part of the pixels. That is, the complementary color calculation for all the pixels is information confidentiality of the entire display image, and the complementary color calculation for a part of the pixels is equivalent to local confidentiality of information for only the complementary color calculated portion.

FIG. 5 shows a block circuit of a visual information concealment device for realizing local information concealment. However, the circuit configuration after the time division unit 3 is the same as that in FIG. 1, and is therefore omitted.

In order to locally conceal information, it is necessary to set a pixel area that covers the object of concealment.
Therefore, in the block circuit of FIG. 5, the complementary color area setting unit 13 is connected before the complementary color calculation unit 2.

The complementary color area setting unit 13 determines the size, shape, position on the screen and composite color of the pixel area to be subjected to complementary color calculation. Since the complementary color area is composed of pixels, the pixels in the complementary color area may be flagged, or if the area is geometrically simple, the boundary line may be represented by a mathematical expression. These settings are
The person who wants to conceal the information may manually perform it depending on the situation, or may be automatically determined by the program. Alternatively, it may be given in the form of data from the beginning as being constant. As a means for a human to directly set the boundary line of the area, it is conceivable to use an interface such as a light pen, a mouse, and a keyboard. The complementary color area setting unit will be described in detail later.

FIG. 6 is a flowchart showing the local complementary color calculation. However, it is assumed that the composite color A and the complementary color area are given by the complementary color area setting unit 13.

Although the size and shape of the complementary color area can be changed by the complementary color area setting unit 13, the display information to be concealed should not be inferred from the size and shape. Paying attention to this, it is possible to show completely different display information to a person other than the operator by using this complementary color area as a kind of geometrical figure different from the confidential object.

The area setting in the complementary color area setting unit 13 can be changed with time. As a result, since the size, shape, position, and composite color of the complementary color area can be determined by the time zone, it is possible to select a target from the display information for each time zone and conceal it.

FIG. 7 shows an example of an image viewed by a person other than the operator in this case. In this image example, three images are arranged side by side, and the state in which the images change with the passage of time is shown in the order from left to right, and the same applies to FIGS. 8 to 12.

In each image, the area inside the polygon 15 in the frame 14 is the area where the complementary color calculation is locally performed. The color of this area is a composite color generated from the color of the original image and the color of the complementary color image. The hatched portion outside this area is the portion 16 of the original image that can be seen by anyone other than the operator.

By changing the shape of the complementary color area with time, a person other than the operator can see the two-dimensional animation. FIG. 8 shows an example of an image viewed by a person other than the operator in this case. In this example,
The complementary color area 17 represented by a triangle is a square 1 with time.
The figure shows that the area changes to 8, and finally becomes a region surrounded by a circle 19.

When the object to be concealed moves on the screen with time, the complementary color area can also be moved according to this movement. In this case, the position of the complementary color area is determined in the complementary color area setting unit so that the relative positional relationship with the confidential object does not change. At this time, the shape and size of the area may be constant, but may be changed as long as the area covers the confidential object. FIG. 9 is an example of an image viewed by a person other than the operator in this case. According to this image example, the inside of the square in each frame 14 is the complementary color area 20. The circle 21 drawn in this area 20 is a secret image in this case, and the square of the complementary color area 20 moves with the movement of the circle 21. However, in reality, anyone other than the operator cannot see the circle 21.

On the other hand, there is a case where it is made unknown to anyone other than the movement method of the confidential object and the position information operator. In this case, it is necessary to set a pixel area that covers the moving range of the hidden object as a target of complementary color calculation.

For example, if it is known that the confidential object does not enter the upper side of the screen, the entire lower side of the screen is set as the target area for complementary color calculation. FIG. 10 is an example of an image viewed by a person other than the operator in this case. In this case, the circle 2 to be hidden
In the case of 1, the range 22 that moves on the screen is known in advance.

It is also possible to gradually reduce the area of the complementary color area from the entire screen with time, thereby narrowing the concealment target area of the display information. The reverse is also possible. FIG. 11 shows three image examples viewed by a person other than the operator in this case. At first, all three colors are complementary colors of the entire screen 23. The top two are squares 2 over time
4 shows that the complementary color area of No. 4 is small. In the last example, the complementary color area is divided into four areas, and the area 25 becomes smaller in each area. In this way, the display information of the original image can be gradually shown to a person other than the operator. On the contrary, displaying images in order from right to left corresponds to gradually increasing the concealment targets.

Further, the complementary color area setting unit 13 can set a plurality of complementary color areas. This allows
You can select multiple objects from the displayed information and keep them secret. FIG. 12 is an example of an image viewed by a person other than the operator in this case. In this example, the shape, the composite color, and the number of the complementary color areas 26 change with time.

FIG. 13 shows an example of a flowchart of the complementary color calculation when there are a plurality of complementary color areas. Area 1, area 2, ..., Area n in this flowchart are determined by the complementary color area setting unit 13. Further, the composite color also corresponds to each area in the complementary color area setting unit 13 and is A1, A2,
…, An has been decided.

Since the composite color of each area can be set with different colors in the complementary color area setting section 13, a plurality of complementary color areas can be combined on the screen to form a mosaic image different from the operator to be hidden. It is possible to show. FIG. 14 is an example of an image viewed by a person other than the operator in this case. In this example, the shape and the composite color are different.
The one complementary color area 27 constitutes a rectangular area. The outside of this rectangle is the part 16 of the original image.

By changing the shape, size, position, and composite color of each complementary color area with the time in the complementary color area setting unit, complicated information can be provided to anyone other than the operator. Since it is possible to fill the entire screen with a plurality of complementary color areas, it is possible to regard each area as a minimum unit that constitutes an image and create a completely different image for anyone other than the operator.

Pixels are considered to be the limit where the complementary color areas that make up the entire screen are made smaller. Therefore, a more complicated image can be shown to a person other than the operator by performing the complementary color calculation for each pixel within the range of the constraint of the original color and the complementary color described above and the composite color created from them.

Next, the complementary color area setting section 13 will be described in detail.

The complementary color area covering the object to be hidden is determined by the complementary color area setting section 13. The setting method is as follows.
As described above, the following three methods are possible.

(1) A person directly sets an area.

(2) The area is automatically set by the program.

(3) The setting is made by the area data prepared in advance.

In the case of the method (1), since an interface for human input is required, the complementary color area setting unit 13 as shown in FIG. 15 which can be directly set by human is provided. This complementary color area setting unit 13
Is composed of a region input unit 31, a region generation unit 32, and a region storage unit 33. The area input unit 31 is an interface for human input, and is, for example, a mouse or a keyboard. The area generation unit 32 differentiates the complementary color area and the non-complementary color area based on the input data by encoding the area or the like. The area storage unit 33 stores codes generated by the area generation unit 23 for all pixels on the screen. That is, the area storage unit 33 is like a data file that stores area data. Therefore, when there is no new area input, the data stored in the area storage unit 33 is sent to the complementary color calculation unit 2 as a complementary color area. When a new area is input and the complementary color area changes, the data in the area storage unit 33 is rewritten with new data.

Next, a method of setting the complementary color area concretely by the complementary color area setting unit 13 of FIG. 15 will be described.

If the shape of the complementary color area is limited to a rectangle, this area can be determined by designating two opposing vertices on the screen using an input device such as a mouse, as shown in FIG. I can. The region is encoded using the pixel coordinates of these two vertices as input data. In this case, the pixel coordinates are xmin <x <xmax, ymin <y
If <ymax is satisfied, it means that the pixel is inside the complementary color area. Therefore, a code 1 is assigned to a pixel satisfying this condition, and a code 0 is assigned to a pixel outside the condition.
The encoded data of the entire screen created in this way is shown in FIG.
As shown in FIG. 6, it is stored in a data file or the like and sent to the complementary color calculation unit 2.

In the case of method (2). The complementary color area setting unit 13 as shown in FIG. 17 is used. According to this, the program for determining the complementary color area is generated by the area generation unit 32. That is, the program determines the shape, size, and position of the area, which is performed by a human in the method (1). At the same time, the area is encoded to generate area data. When it is desired to automatically change the shape, size, or position of the complementary color area with time, it is necessary to control it by a program. When the original image is a CG image generated by a program, the shape, size, and position of the confidential object are determined at the stage when the original image is generated.
These can be used as input data of the area generation program. That is, as shown in FIG. 18, when the concealed object moves on the screen, the position is sent to the area generation unit 43 as the input data of the area generation program at the stage where the original image is generated by the image generation unit 30. To be Then, a rectangular or circular complementary color area having a certain size centered on that position is created in the area generation unit 32.

In addition to the case where the area is determined on the spot by the program as described above, several area data files 34 are prepared as shown in FIG.
It is also possible to select them automatically by a program. In this case, the complementary color area can be changed by using a triangular area data file at one time and a circular area data file at another time.

In the case of the method (3), only one area data file is used. That is, as shown in FIG. 20, the complementary color area setting unit 13 is provided with only the area storage unit 33. Therefore, the first given complementary color area is always used.

Next, if there are two operators and these two wear the same polarized glasses, both will see the same original image, but one of the two will have a complementary color image. If you are wearing polarized glasses that pass the synchronized polarized light, you can see the original image on one side and the complementary color image on the other side. However, as described above, since the original image and the complementary color image are not independent of each other but have a complementary color relationship with each other, even if two operators look at different images, the colors are different. Geometrically, they are seeing the same image, and information is not hidden from each other.

Therefore, instead of the original image and the complementary color image, as shown in FIG. 21, the A image and the B image having completely different information independent from each other are alternately selected by the time division unit 3, Moreover, two operators can wear different polarizing glasses to see different display information. However, the A image and the B image are
5 and the image input unit 36 respectively, and the data is sent to the time division unit 3, so that a person other than the operator sees an image in which the A image and the B image are overlapped with each other. Information confidentiality cannot be realized.

On the other hand, according to the embodiment shown in FIG. 22, the input A image and B image are respectively passed as original images to the complementary color calculating section 37 and the complementary color calculating section 38, and two complementary color images are obtained. Is generated. That is, in addition to the A image and the B image, a complementary color image of the A image and a complementary color image of the B image are newly generated. The composite color created by these two types of original image and complementary color image can be set to be the same during complementary color calculation.

Next, in the time division section 3, these four images are repeatedly switched in the order of the A image, the complementary color image of the A image, the B image and the complementary color image of the B image. Then, the polarization switching unit 5 switches so that the two types of polarized light are respectively synchronized with the A image and the B image. Here, the switching cycle needs to be shorter than in the case of only two images of the original image and the complementary color image. For example, if the switching cycle of only two images of the original image and the complementary image is 1/60 seconds, the time required for the original image to appear once and appear again is 1/30 second. In the case of the current switching of four images, if the time required for the A image to appear once and to appear again is similarly set to 1/30 second, the switching cycle must be set to 1/20 second.

In this way, the first operator wearing the polarizing glasses that pass the polarized light in synchronization with the A image and the second operator wearing the polarizing glasses that pass the polarized light in synchronization with the B image are different from each other. You will see the image. Moreover, since only the image canceled by the complementary color image can be seen by a person other than the operator, the display information can be concealed from the person other than the operator.

[0063]

According to the present invention, the complementary color calculation unit generates an image having a complementary color relationship with the target image, and the complementary color image and the original image are displayed on the display in a time division manner. The synchronized polarization switching unit is arranged between the display and the operator, and the image information is extracted by the polarized glasses, so that the display information cannot be seen by anyone other than the operator,
Only the operator can get the display information. Therefore, there is an effect that the visual information can be concealed.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a visual information concealment device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a process of generating a composite image by time-divisional display of an original image and a complementary color image.

FIG. 3 is a diagram showing a flowchart of an example of complementary color calculation.

FIG. 4 is a diagram showing a graph showing a composite color dependency of an original color and a complementary color.

FIG. 5 is a block circuit diagram of a visual information concealment device that locally conceals information according to another embodiment.

FIG. 6 is a diagram showing a flowchart of an example of local complementary color calculation.

FIG. 7 is a diagram of an image viewed by a person other than an operator, in which the complementary color area changes with time.

FIG. 8 shows that the shape of the complementary color region changes with time,
The figure of the image which people other than an operator see.

FIG. 9 is a diagram of an image viewed by a person other than the operator regarding the setting of the complementary color area when the concealment target moves with time.

FIG. 10 is a diagram of an image viewed by a person other than the operator, which is related to the complementary color area setting when it is desired to keep the information related to the movement confidential when the confidential object moves with time.

FIG. 11 is a view of an image viewed by a person other than the operator regarding the decrease and increase in the area of the complementary color region with time.

FIG. 12 is a diagram of an image viewed by a person other than an operator regarding the shape, the composite color, and the number of complementary color areas which change with time.

FIG. 13 is a diagram showing a flowchart of an example of complementary color calculation when there are a plurality of complementary color areas.

FIG. 14 is a diagram of an image viewed by a person other than an operator regarding a combination of a plurality of complementary color areas that changes with time.

FIG. 15 is a block circuit diagram of a complementary color area setting unit when a person directly inputs a complementary color area.

FIG. 16 is a diagram showing setting of a rectangular area on the screen and encoding the area into data.

FIG. 17 is a block circuit diagram of a complementary color area setting unit when a complementary color area is set by a program.

FIG. 18 is a block circuit diagram of a complementary color area setting unit when an area is set by receiving an input from image generation.

FIG. 19 is a block circuit diagram of a complementary color area setting unit when there are a plurality of area data.

FIG. 20 is a block circuit diagram of a complementary color area setting unit when an area is set from one area data.

FIG. 21 is a block circuit diagram of the input unit of the visual information concealment device in a case where two operators view images independent of each other on one screen, which is another embodiment.

FIG. 22 is another embodiment and is an input of a visual information concealment device when considering confidentiality of information to a person other than the operators when two operators view images independent of each other on one screen. Block circuit diagram of the unit.

[Explanation of symbols]

1 ... Image input unit, 2 ... Complementary color calculation unit, 3 ... Time division unit, 4 ...
Image output unit, 5 ... Polarization switching unit, 6 ... Synchronization control unit, 7 ... Polarization filter, 13 ... Complementary color region setting unit, 31 ... Region input unit, 32 ... Region generating unit, 33 ... Region storage unit, 34 ... File, 35 ... Image input section 1, 36 ... Image input section 2, 37
... Complementary color computing unit 1 38 ... Complementary color computing unit 2,

Claims (1)

[Claims] 1. An information input unit for inputting information to be concealed, a complementary color calculation unit for generating a complementary color image having a complementary color relationship with a display image of the information input by this information input unit, and A time division unit for time-divisionally displaying the complementary color image generated by the complementary color calculation unit and the display image, and the time division display of the display image and the complementary color image sent by the time division by the time division unit. An image output unit, a polarization switching unit for switching polarization in synchronization with the time division timing in the time division unit, and for extracting the display image from the images displayed in the time division according to the time division timing of the polarization switching unit. And a polarization filter provided on the observer side.