KR100538140B1 - Method for displaying a private image using a public monitor - Google Patents

Abstract

In order to improve real-time masking image generation, slow light response of the shutter, and light intensity density difference, monitor frame through integrated generation of original-induced image and disturbance image, color table conversion, intermediate state shutter opening, and boundary region processing of image frame Disclosed are a private display method and system in which two or more different image frames are displayed in one cycle and shutters are smoothly opened and closed correspondingly. The present invention provides a method for outputting a private image using a public monitor, the method comprising: selecting an arrangement rule of a private image and a masking image such that only a specific area of the monitor is private; and masking the private image and masking according to the arrangement rule. Generating a sequence of an image, generating a signal for opening and closing a shutter device corresponding to the image sequence so that only a specific region of the monitor is private, and generating the private image and the masking image according to the image sequence pattern. Outputting to the monitor and opening and closing the shutter device according to the shutter opening / closing signal.

Description

How to output a private video using an open monitor {METHOD FOR DISPLAYING A PRIVATE IMAGE USING A PUBLIC MONITOR}

The present invention relates to an apparatus and a method for outputting a private image, and more particularly, to an apparatus and a method for outputting a private image so that a non-licensed person cannot see in a public display.

Portable terminal devices such as mobile phones, personal digital assistants (PDAs), notebook computers, and desktop personal computers (PCs) are frequently used in public places. At this time, the contents of the display monitor can be seen by everyone within the viewing distance of the display. Because of this security issue, when you use your computer to write text, mail, chat, watch videos, and so on, there are many restrictions on using your computer. In addition to the use of personal computers, privacy issues can also arise when companies, governments, and others work on computers with confidential documents. In addition, display security issues exist in various fields. For example, an automatic teller machine (hereinafter referred to as "ATM") is placed in a public place, so secret information such as password keystrokes and transaction details of ATM users can be easily exposed. Therefore, it is useful to develop a display that provides private information to authorized users on a publicly viewable monitor, while an unauthorized person cannot view private information on the same monitor.

Early liquid crystal display (hereinafter referred to as "LCD") monitors have a narrow viewing angle, which causes the screen to appear dark when viewed slightly sideways from the front. Since this point of view was inconvenient in terms of general use, technological advances have been made in the direction of widening the viewing angle, but from a security point of view, it has some security and is the most basic form of private display. Can be. A display with a micro blocker that further develops this concept is disclosed in US Pat. No. 5,528,319 (the inventor is Russel). However, this method has a disadvantage in that the contents of the display are completely exposed to the person behind the user.

A more advanced concept of private display is the security LCD released by Scepter in 1998. This product using polarized light removes the polarizing plate inside an ordinary LCD monitor and allows the user to use polarized glasses. However, this product is inconvenient for general use because privacy can be perceived only when privacy is not important. In addition, unlicensed people who wear glasses with simple polarization characteristics, such as general sunglasses, can see the contents, so the security is low. Eventually the product failed and was discontinued in the market. With a slight refinement of this approach, in 2001, MMI (http://www.man-machine.com/invisivw.htm) introduced a product that can be attached to or detached from a polarizer. However, this product also has the disadvantage that unauthorized users wearing simple polarized glasses such as sunglasses can view the contents.

The most complete private display is a head-mounted display (hereinafter referred to as "HMD"). However, HMD has a problem that the display and the optical system are both contained in glasses, which is expensive, heavy to wear, and high in power consumption.

In the present specification, one display screen distinguished by vertical sync of a monitor is called a monitor frame, and one piece of image data is called an image data frame. One image data frame may be the same size or different from one frame of the monitor. A private image (hereinafter referred to as "P image") is a private private image of an authorized user. The masking image (hereinafter, referred to as "M image") is an image that blocks unauthorized users from viewing a private image of an authorized user.

Private displays are now being implemented that use shutter glasses to protect private information. It is considered to be the most competitive way at present because of its low cost, light weight, and plenty of room for performance. Private displays must meet all three performance criteria: user visual perception, bare-eye security, and anti-spy security. 'User perception performance' means that the authorized user can see the image clearly without any visual discomfort or fatigue, and 'eye-eye security performance' prevents the unauthorized person without the shutter from seeing the image clearly. Security against counterspy 'is to prevent unauthorized or intentional spypers with shutters from seeing the images clearly.

In the "synchronous" method of Sun Microsystems (hereinafter referred to as "the method of Sun Microsystems") disclosed in US Patent No. 5,629,984, a private image data frame (hereinafter referred to as "P frame"). And the masking image data frame (hereinafter referred to as "M frame") are displayed at the same time as the frame synchronization of the monitor, and the shutter glasses are opened and closed at the same time. Make it visible. The replacement of the P frame and the M frame is performed at a ratio of 1: m (m = 1, 2, 3, ...) that displays the M frame every time the P frame is displayed one time. This method satisfies the 'eye-eye security performance' but does not consider the 'anti-spy security performance', and as m increases, the number of private images is smaller than the masking video, so the 'user visual perception performance' also decreases. It is not effective to cover the private image by generating a simple white flash image with the M frame masking image. Whenever the shutter needs to be opened and closed, it is easy for the spy to intercept the shutter by sending the shutter open / closed signal without encryption.

In IBM's "Asynchronous" method (hereinafter referred to as "IBM method") disclosed in GB 2360414A, P / M data frames and shutter glasses are displayed while P frames and M frames are displayed without matching the frame synchronization of the monitor. I'm motivating. In this method, the display time of the P / M image data frame is variable and encrypted, thereby improving 'security against spoilers'. In addition, by encrypting and transmitting the shutter open / close signal to the shutter under the premise of the timer on the shutter side, the security performance against the spy explorer was enhanced to prevent the spy from intercepting the shutter open / close signal. However, due to the asynchronous of the image frame and the monitor frame, 'user visual performance' is reduced. It is inconvenient for the user to see because the light intensity density varies according to the area of the monitor, and it is inconvenient because image unevenness occurs at the boundary where the P and M images are switched due to the combination of the asynchronous characteristics and the finite response time of the shutter. In addition, the P-display is more likely to be displayed in a specific area (top) of the monitor, thereby degrading 'eye-eye security' and 'anti-spy security'. In addition, since the image data frame repeatedly replaces P and M, the probability that the prober can view the P image through tuning is increased. In addition, since masking image data of M frames is generated as a simple random pattern image, it is not effective to cover a private image. There is also room for improvement in that a timer is required on the receiving side for the encrypted transmission of the shutter open / close signal.

The present invention proposes a private display using an area division image arrangement sequence method for displaying two or more different image frames during one monitor frame period. Monitor Frames Displaying multiple different video frames during one cycle and effectively opening and closing the shutter can make it very difficult for a spy to decipher a private video.

However, the conventional private display has a limitation in displaying and privately viewing two or more different image frames during one period of the monitor frame due to the slow light response of the shutter, difficulty in generating real-time masking images, and light intensity density differences. Accordingly, in the case of the synchronous private display, only one type of image frame is displayed during one monitor frame period. In the IBM method, only one type of image frame is displayed or only two types of image frame are displayed for one period of the monitor frame, but the slow light response of the shutter cannot be compensated for, and the light intensity density difference is generated for each area of the monitor of the image. there was. In particular, since the probability of displaying a P image is increased in a specific area of the monitor (top), the area has a higher light intensity density than other areas.

If a display frame can display two or more different image frames in one cycle and the shutter can be smoothly opened correspondingly, a better private display can be obtained.

It is an object of the present invention to provide a private video output method that can improve security performance against spying by displaying two or more different video frames in one monitor frame period while satisfying user visual perception performance.

In the present invention for achieving the above object, in order to improve the real-time masking image generation, slow light response and light intensity density difference problem of the shutter, integrated generation of original induction image and disturbance image, color table conversion, intermediate shutter opening and closing And it proposes a private display method and system that displays two or more different image frames in one period of the monitor frame through the boundary region processing method of the image frame and the shutter opening and closing accordingly.

The present invention provides a method for outputting a private image using a public monitor, comprising: selecting an arrangement rule of a private image and a masking image such that only a specific area of the monitor is private; and masking the private image and masking according to the arrangement rule. Generating a sequence of an image, generating a signal for opening and closing a shutter device corresponding to the image sequence so that only a specific area of the monitor is private, and generating the private image and the masking image according to the image sequence pattern. And outputting to the monitor and opening and closing the shutter device according to the shutter opening / closing signal.

In another aspect, the present invention provides a method for outputting a private video using a public monitor, comprising the steps of selecting a rule for arranging a private video and a masking video alternately at least two times during one frame of the monitor; Generating a sequence of a private image and a masking image according to the image sequence, generating a signal of opening and closing a shutter device according to the image sequence, and outputting the private image and the masking image to the monitor according to the image sequence. And opening and closing the shutter device according to the shutter opening / closing signal.

In another aspect, the present invention provides a method for outputting a private video using a public monitor, comprising the steps of selecting a rule for arranging a private video and a masking video alternately at least two times during one frame of the monitor; Generating a private video sequence and a masking video sequence; generating a signal for opening and closing a shutter device according to the video sequence; and outputting the private video and the masking video to the monitor according to the video sequence pattern. And opening and closing the shutter device according to the shutter opening / closing signal, wherein a masking image having different characteristics is output for each area of the monitor.

In another aspect, the present invention provides a method for outputting a private video using a public monitor, comprising the steps of selecting a rule for arranging a private video and a masking video alternately at least two times during one frame of the monitor; Generating a private video sequence and a masking video sequence; generating a signal for opening and closing a shutter device according to the video sequence; and outputting the private video and the masking video to the monitor according to the video sequence pattern. And opening and closing the shutter device according to the shutter opening / closing signal, wherein a private image or a connection image is output during the response time of the shutter device.

According to the present invention as described above, it is possible to further improve the security performance against the spy attacker while satisfying the user visual perception performance.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components or signals.

Private displays can be widely used in various monitor display devices such as desktop PCs, notebooks, PDAs, mobile phones, TVs, DVDs, ATM / CD machines, and door lock information input devices. A description will be given of an embodiment of a PC monitor, which is the most typical of these. Those skilled in the art can easily change and apply to other display devices. In general, other display devices have a simpler structure than a PC monitor, and thus may implement a private display without some of the essential components of the PC monitor embodiment.

1 is a basic configuration diagram of an embodiment applied to a notebook PC. As shown, a computer device 104 having a monitor 102, shutter opening and closing means 106 for filtering light, wired and wireless communication means 108 for connecting the computer 104 and the shutter opening and closing means 106. , Private display software (not shown). Computer 104 may include private display software stored in computer readable memory. The computer 104 displays a private image and a masking image for masking the private image on the monitor 102 by the user's request or by itself, and transmits a corresponding shutter opening / closing signal to the shutter opening / closing means 106 to open and close the shutter. Activating the means 106 ensures that only authorized users can view private images. The computer 104 refers to various information devices that display and operate an image on a monitor such as a desktop PC, a notebook, a PDA, a mobile phone, a TV, a DVD, an ATM / CD device, a door lock information input device, and the like.

The shutter opening and closing means 106 may be mechanical or photoelectric such as a liquid crystal shutter. The shutter opening and closing means 106 may be manufactured in various forms such as shutter glasses having one or several shutter lenses, a shutter structure having a support, and a shutter cap. 1 shows shutter opening and closing means in the form of shutter glasses.

When the computer 104 is used in a bright environment, the ambient light reflected from the monitor 104 may be incident on the user's eye, resulting in a low contrast of the monitor image. In one embodiment, an ambient light filter (not shown), such as “3M ^™ Privacy Computer Filters” sold by 3M, is attached to the front of the monitor 102. The ambient light blocking filter is a light filter whose light transmittance depends on the angle of incidence. The ambient light filter consists of a film with a microlouver blocker that functions as a sunscreen window blind, blocking out incident light from above a certain angle. In another embodiment, a brightness enhancement film, such as "Vikuiti ^™ Display Enhancement Films" sold by 3M, is attached to the front of the monitor 102 to improve the brightness of the monitor. When the filter is attached to the front surface of the monitor 102, it is effective to block the ambient light incident and reflected on the monitor 102, but cannot directly block the ambient light incident on the shutter opening and closing means 106. In another embodiment of the present invention, the ambient light blocking filter 202 is attached to the shutter opening and closing means 106 in order to block the ambient light directly incident to the shutter opening and closing means 106. When the ambient light blocking filter 202 is attached, the contrast of the image perceived by the user increases, but the overall brightness decreases slightly. In another embodiment, it is possible to mount the filter 202 in bright places and to detach it in dark places.

In the present specification, the shutter opening and closing sequence state value (state information) is a value quantitatively indicating the opening and closing degree of the shutter, and the shutter opening and closing sequence is a sequence of shutter opening and closing state values corresponding to the image sequence [0, 1, 0, 0, 1 , 0, ...]. The shutter open / close signal is a signal transmitted to control the opening / closing operation of the shutter according to the shutter opening / closing sequence, and generally includes one or several shutter opening / closing sequence state values.

3 is a configuration diagram of a system using a software-based dedicated driver according to an embodiment of the present invention. The software method means that the software implements functions except for the shutter opening and closing means 306 and the transmission / reception interface unit 308. Here, the dedicated driver 310 refers to a driver that accesses the video controller 312 such as a graphics card separately from the graphics driver 314 in the PC 302 to implement a private display in real time.

The private display control block 318 includes a security performance control unit, an encryption unit, a user authentication unit, and a management unit, and authenticates a user from the user interface 320, and displays a display security level according to an authorized user's authentication level and a user's input. Set up and manage. The user authentication method may be authenticated by receiving an identification number (hereinafter referred to as “ID”) and a password input of the user from the user interface 320. In addition, user authentication can be performed by connecting an authorized shutter opening and closing means 306 without inputting an ID and a password. In addition, the user can be authenticated by connecting the permitted shutter opening and closing means 306 and receiving input of the authorized user ID and password. Authorization and activation of the shutter opening and closing means is performed with a serial number of a product embedded in a read only memory (ROM) (not shown) of the shutter opening and closing means 306. The private display control block 318 receives the monitor information from the monitor information obtaining means 328 and generates the image data frame sequence generating means 322, the shutter opening and closing sequence and the shutter opening and closing signal based on the authentication level and the display security level of the user. The control unit 324 controls the masking image generating unit 326. The monitor information obtaining unit 328 reads information such as the resolution of the monitor 304, the refresh cycle time, the vertical sync, the horizontal sync, and the like.

The image data frame sequence generating means 322, the shutter opening and closing sequence and the shutter opening and closing signal generator 324, and the masking image generating means 326 correspond to the image data corresponding to the user's authentication level and display security level and the user's additional selection. A frame sequence, a shutter open / close sequence, a shutter open / close signal, and a masking image are respectively generated. The shutter open / close sequence and shutter open / close signal generation unit 324 generates a shutter open / close sequence in synchronization with the image data frame sequence, and generates a shutter open / close signal at a current time point in accordance with the shutter open / close sequence.

The dedicated driver 310 provides the masking image generated by the masking image generating means 326 to the video memory 340 according to the generated image data frame sequence, or self-masks the image according to the instruction of the masking image generating means 326. To generate the video memory 340 to provide to the video memory 340 or to control the color table in real time. The dedicated driver 310 also controls the image transmission to the monitor 304 by causing the video controller 312 to switch the private image memory block and the masking image memory block according to the generated image sequence.

The transceiver 308 transmits a shutter open / close signal to the shutter open / close means 306. Also, the transceiver 308 may transmit an encrypted shutter open / close signal to an authorized user by using an encryption means (not shown). The transceiver 308 and 336 may be implemented as a wired link such as USB or a serial link or a wireless link such as IR or RF (FM, AM, Bluetooth). The video controller 312, such as a graphics card, includes a video memory 340, and monitors the original private image received from the graphics driver 314 and the masked image received from the dedicated driver 310 according to the image data frame sequence. Display on the screen.

As shown in FIG. 3, the shutter opening / closing means 306 may include a transceiver 336, a decoder / authentication means 330, a shutter controller 332, and a shutter 334. The transceiver 336 receives the encrypted shutter open / close signal transmitted from the transceiver 308 and transmits it to the decoder / authentication means 330. The decoder / authentication means 330 decodes the shutter open / close signal to obtain a shutter open / close sequence state value, and the shutter controller 332 opens or closes the shutter unit 334 completely or in an intermediate state according to the shutter open / close sequence state value. .

The display security level is set to a performance level according to 'eye security' for unlicensed people who do not have shutters, and 'spy security performance' for non-licensed users who have different shutters. In general, the higher the level of display security, the lower the user's visual perception performance, such as user's visual comfort and image clarity. These display security levels can be defined in various ways. As an example, the first level is that an unauthorized person may not even perceive the approximate type of user private image even after viewing the monitor for a long time over a certain time. As the strictest privacy protection, for example, you don't know whether the user is doing a word or watching a video. The second level may be to perceive the approximate type of user image if the unauthorized user views the monitor for a certain time. However, some of the contents of the user image information cannot be grasped. For example, even if a user knows whether to watch a video, it does not know whether it is a movie or a chat. The third level can roughly grasp a portion of the user image information content if the unauthorized user sees the monitor for a certain time. However, most of the contents of the user image information cannot be grasped. For example, you cannot know the content of the word you type. You can tell if the user is watching a movie movie, but not the content. The fourth level can accurately grasp a part of the contents of the user image information if the unauthorized person sees the monitor for a specific time or more. However, most of the contents of the user image information cannot be grasped. For example, you might know a bit of the word you type. You can see a little bit of the content of the movie that the user perceives. The fifth level allows the unauthorized person to grasp a substantial part of the content of the user image information. However, I feel uncomfortable with my visual perception. As another example, an additional figure of merit may be added to this performance level to the extent that user private images and intentionally disturbing masking images can be recognized by an unauthorized person. In this case, various display security levels can be set, such as the performance level.

4 is a block diagram of a video controller 312 shown in FIG. As shown, the private image memory blocks are represented by P1 to Pm, and the masked image memory blocks are represented by M1 to Mn according to the image memory location. P1 to Pm are frames operated by the system, and M1 to Mn are masking frames generated by a dedicated driver 310 which is a kernel driver for masking. Each memory block is selected through a method such as flipping to monitor the image via a color table 402 and a RAMDAC / DVI monitor connection 404 serving as an image value (RGB value) converter. 304). As an example, each of the memory blocks P1 to Pm and M1 to Mm corresponds to one monitor frame size. The dedicated driver 310 creates a thread and sends the image data to the masking image memory blocks M1 to Mn that are arbitrarily held in the video controller 312 whenever there is a spare time in the CPU. Update In addition, the dedicated driver 310 checks the vertical synchronization state Vsync_ST in a polling manner from the vertical synchronization status register 406 of the video controller 312 or is generated in the vertical synchronization signal generating circuit 408 and caught in the system. By hooking the coming vertical sync interrupt (Vsync_INT), one of the video frames P1 to Pm and M1 to Mn is selected in synchronization with the vertical sync signal, and the start address of the frame is set to the frame of the video controller 312. Write to a start address register (not shown) so that the selected picture frame is displayed.

In addition, the selected video frame may be displayed in synchronization with a specific horizontal synchronization signal. In the color table changing method, a private driver may change a color table randomly and convert an arbitrary image value while a private image block is transmitted to a monitor, thereby converting the private image into a masking image. In addition, a filter driver (not shown) may be inserted instead of the dedicated driver 310 of FIG. 3. The filter driver functions like the dedicated driver 310 and works like a filter when the graphics driver 314 approaches the video memory 340. Alternate driver methods can also be used. This method integrates a dedicated driver function into an existing graphics driver and controls it as a driver.

5 is a view for explaining a partial screen private display according to the present invention. One of the simplest embodiments of the monitor frame region segmentation image placement sequence methods of the present invention is a partial screen private display. In order to be limited by the slow response of the monitor pixels or the slow response of the shutter opening and closing means or to reduce the masking image calculation time, it may be advantageous to use only a portion of the monitor screen as a private display. In one embodiment, the P / M image sequence is displayed as shown in FIG. 5A. The second screen shows that the PMP video frame is displayed in one monitor frame period. Each PMP image frame may be displayed in synchronization with a specific monitor Hsync, and may be displayed in synchronization with a monitor and in synchronization with data synchronization. At this time, the shutter opening and closing sequence may be of both types as shown in FIG. 5A. The left shutter opening and closing sequence is opened and closed in synchronization with the monitor vertical synchronization. The right shutter opening and closing sequence is opened and closed in synchronization with the P / M image sequence replacement. However, when the shutter is opened and closed with the right shutter opening and closing sequence, the light intensity density of the upper and lower images is larger than that of the center of the screen.

In another embodiment, a masking image segmentation method is used. In the masking image segmentation method, a masking image Ms with strong masking is generated in a region where the shutter is completely blocked (mainly an intermediate region), and a masking image Mw with weak masking is generated in an region where the shutter is incompletely blocked. Masking images with weak masking include connection images, unclear images, or images that do not include frequencies sensitive to human visual perception. In this case, the MwMsMw video frame is displayed in one monitor frame period.

When the 'eye security' is different for each display area, the user creates a P / M image sequence and a shutter opening / closing sequence when the user wants to move the private display area with high 'eye security' by using a mouse scroll in the user interface. . In another embodiment, the P / M image sequence and the shutter opening / closing sequence are sequentially changed at a preset speed so that the private display area is scrolled and shown to the user sequentially so that the entire screen is displayed.

In another embodiment, the display is displayed as a P / M image sequence as shown in FIG. 5B. The second screen shows that the PMP video frame is displayed in one monitor frame period. Each PMP image frame may be displayed in synchronization with a specific monitor Hsync, and may be displayed in synchronization with a monitor and in synchronization with data synchronization. In the middle region where the M image is displayed, the P image is displayed after the monitor Hsync, and the M image is displayed after a predetermined time elapses, and the P image is displayed again after the predetermined time. At this time, the shutter opening and closing sequence may be of both types as shown in FIG. 5B. The left shutter opening and closing sequence is opened and closed in synchronization with the monitor vertical synchronization. The right shutter opening and closing sequence is opened and closed in synchronization with the P / M image sequence replacement. However, when the shutter is opened and closed with the right shutter opening and closing sequence, the light intensity density of the up, down, left, and right images is larger than that of the center of the screen. The partial screen private display may be implemented in a software (SW) method or a hardware (HW) method.

An embodiment of a private display method of displaying two or more different image frames during a monitor frame period is illustrated in FIG. 6. The region division image arrangement sequence may be displayed in synchronization with the monitor Hsync, and may be displayed in synchronization with the monitor and in synchronization with data synchronization. 6 is an example of a sequence in which an image frame is arranged by dividing the display frame into three regions every monitor frame. In the above embodiment, the P / M image sequence is displayed in the order of (PMP), (PMP), (MPM), and (PMP). In this embodiment, the shutter opening and closing sequence consists of only two shutter states, open and closed. The shutter open / close signal transmission pulse sequence transmits the shutter open / close signal when the shutter state of the shutter open / close sequence changes as shown in Fig. 6C, and further transmits the shutter open / close signal at any instant when the shutter state does not change. In FIG. 6C, the current shutter state maintaining shutter open / close signal that transmits the shutter open / close signal when the shutter state is changed to gray at an arbitrary moment is not displayed in white. Maintaining the current shutter state The shutter open / close signal is a signal for preventing the salt probe from decoding the shutter open / close signal. In another embodiment, the shutter open / close signal is transmitted only when the shutter state of the shutter open / close sequence changes. In another embodiment of the present invention, the shutter opening and closing sequence is made of a multilayered state including an intermediate state shutter state. In FIG. 6A, each P image display cycle time and M image display cycle time are fixed in one embodiment and vary in another embodiment. By varying the P image display cycle time and the M image display cycle time, it is possible to improve the 'stalker counterfeit security performance' for the salt probe.

According to the present invention, the area segmentation image arrangement sequence method displays a plurality of different image frames in one period of the monitor frame, and thus, more various masking image providing methods can be used. In the present invention, a masking image is provided using a primitive induction image method such as reversed phase, a disturbance image method, a mixing method of a primitive induction image and a disturbance image, and the like. In an embodiment, a masking image having different characteristics may be provided for each monitor screen division region. For example, as shown in FIG. 6, in the case of the (PMP), (PMP), (MPM), and (PMP) sequences, the M image of the intermediate region is generated by mixing the original induction image and the disturbance image. The M image of the lower region may be generated using the original induction imaging method. For example, M images of a specific region such as an intermediate region may be quickly updated and provided, and M images of other regions may be slowly updated and provided for effective real-time masking image generation. According to an embodiment of the present invention, a priming induction image and a disturbing image such as dynamic reverse phase are generated and provided to each area in real time using a real-time color table change method.

FIG. 7 is a view for explaining a private image grouping method of a region division image arrangement sequence according to the present invention. If each P / M image display cycle time is changed for 'investigator's security performance,' private images are displayed more frequently in certain parts of the monitor than in other parts. When the user views, the light intensity density of the specific portion is greater than the light intensity density of the other portion, which may cause inconvenience. In order to solve the above light intensity density difference problem, the present invention proposes a closed image grouping method. The private video grouping method is such that m complete private video screens are displayed in grouped units during n monitor frames. In the embodiment as shown in FIG. 7A, P / M images are averaged in a P: M = 1: 1 ratio and one complete private image screen is displayed in grouped units during two monitor frames. When the (PMP) and (MPM) screens are displayed during the grouping unit, one complete private video screen is combined and shown to the user. At this time, the region division image switching boundary point on the (PMP) screen is made to coincide with the region division image switching boundary point on the (MPM) screen. In the embodiment as shown in FIG. 7B, P / M images are averaged in a P: M = 1: 2 ratio and one complete private image screen is displayed in grouped units for three monitor frames. If (PMM) = (PM), (MPM), (MMP) = (MP) screens are displayed during the grouping unit, one complete private video screen is combined and shown to the user. At this time, the region division image switching boundary points on each screen are matched. In another embodiment, m complete private video screens are displayed in grouped units during n monitor frames in general, such as two complete private video screens are displayed in grouped units during five monitor frames. In another embodiment, when private image grouping is performed, a specific region may be subtracted and grouped without completely grouping m private image screens for n monitor frames. There is no great inconvenience for the user's visual perception unless the group is consistently subtracted from the same area.

8 is a view for explaining a private video grouping variable according to the present invention. In one embodiment of the present invention, the private video grouping is changed to improve the security against counterinvestigators. An embodiment of a closed image grouping variable is illustrated in FIG. 8. In the embodiment as shown in FIG. 8A, the grouping unit is varied in such a manner that the grouping of one complete private video screen for two monitor frames is performed in the method of grouping one complete private video screen for three monitor frames. do. The spy detector cannot cope with the variable, thereby improving security. In the embodiment as shown in FIG. 8B, the grouping is varied in such a manner that the number of screen area divisions is changed from three to four while the grouping unit is fixed to group one complete private video screen during two monitor frames.

FIG. 9 is a diagram for explaining a maximum repetition period sequencing method of a region division image arrangement sequence according to the present invention. FIG. In one embodiment of the present invention, a maximum repetition cycle sequence method of inserting aperiodicity into a region division image arrangement sequence is used to improve 'anti-detector security performance.' Whether or not the P / M image sequence is repeated or not is determined based on the monitor frame in each area of the monitor whether it is repetitive in time or non-repeating. As an example, FIG. 9A illustrates an embodiment in which aperiodicity is inserted at the same time point in all areas of the monitor. (PMP), (MPM), (PMP), (MPM), (MPM), (PMP), (MPM)... As shown, aperiodicity is inserted in the fifth monitor frame. The upper and lower areas of the monitor are displayed in the PMPMMPM sequence and the middle area is displayed in the MPMPPMP sequence. In another embodiment, as shown in FIG. 9B, aperiodicity may be inserted at different points in time for each area of the monitor. In this case, (PMP), (MPM), (PMP), (MPM), (MPP), (PMM), (MPM). Is displayed as The upper region of the monitor is a PMPMMPM sequence, the middle region is displayed as an MPMPPMP sequence, and the aperiodicity is inserted into the fifth monitor frame, but the lower region is displayed as a PMPMPMM sequence and the aperiodicity is inserted into the seventh monitor frame. In an embodiment of the present invention, the shutter opening and closing sequence may be generated using the intermediate state shutter opening and closing.

10 is a view for explaining the sequence of the private image and the masking image, the shutter opening and closing sequence, the shutter opening and closing sequence optical response according to the present invention. In the closed display displaying two or more different image frames in one period of the monitor frame of the present invention, it is necessary to solve the light intensity density difference problem due to the slow light response of the shutter opening and closing means. To this end, the present invention proposes a boundary region processing method of an image frame. 10 illustrates the shutter opening and closing sequence and the optical response of the shutter opening and closing sequence according to the P / M image sequence. Ideally, the fast shutter opening and closing means should follow the shutter opening and closing sequence of FIG. 10B at an infinite speed, but exhibits a relative light transmittance characteristic of the type shown in FIG. 10C due to the finite light response characteristics of the shutter opening and closing means. Due to the finite optical response of the shutter opening and closing means, in the boundary area where the P / M image is replaced, the user sees the masking image to be blocked or darkens the private image to be seen. It is a serious problem for the user to see the masked image to be blocked and should be avoided if possible.

In the present invention, as shown in FIG. 11, the shutter response time for the shutter opening / closing sequence is calculated to allow the user to watch a connected image Mb image such as a P image or a blank image during the shutter response time. As shown in FIG. 11A, a private image (P image) or Mb image is provided and displayed during the shutter response time in the boundary area to which the P / M image is switched. This prevents the user from seeing the masking image that should be blocked.

In addition, in order to solve the problem of light intensity density difference due to finite shutter response time, the present invention applies the P image grouping method and the boundary area processing method in an integrated manner. As an example, FIG. 12 illustrates a method for processing a shutter opening and closing sequence optical response and boundary region processing according to region division image arrangement for monitor frames 1 and 2 which are private image grouping units. In the above, all boundary regions were P images. The upper boundary area of the monitor is viewed by the user while the shutter is opened in monitor frame 1 and by the user in the shutter frame closed in monitor frame 2, and the average viewing effect of viewing a single private video with the maximum open shutter Occurs. In this way, the problem of light intensity density difference is solved. The boundary area under the monitor is compensated in the same way.

As another embodiment, FIG. 13 illustrates a shutter response sequence optical response and a boundary region processing method according to region division image arrangement for monitor frames 1 and 2 which are private image grouping units. In the above, all of the boundary regions were connected images Mb images. As indicated by the arrow in the figure, exactly match the start and end positions of the P image on the monitor frames 1,2. In this way, the problem of light intensity density difference is solved. This method is excellent in terms of 'user viewing performance' but is less secure in the area of displaying the connected image Mb, so this area should provide enough masking images in other monitor frames. When the method using the Mb image is used, in one embodiment, a region division image arrangement sequence in which a boundary region is continuously changed is generated and displayed.

Here, the described embodiments are only intended to enable those skilled in the art to easily understand and practice the present invention, and are not intended to limit the scope of the present invention. Therefore, those skilled in the art should note that various modifications or changes are possible within the scope of the present invention. The scope of the invention is defined in principle by the claims that follow.

According to the present invention as described above, it is possible to further improve the security performance against the spy attacker while satisfying the user visual perception performance.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining a connection relationship between a closed video output device and a shutter device to which the present invention is applied.

2 is a block diagram of a shutter device according to an embodiment of the present invention.

3 is a block diagram showing the configuration of a private video output device and a shutter device according to the present invention;

4 is a block diagram showing the configuration of the video controller shown in FIG.

5 is a view for explaining a partial screen closed display according to the present invention.

6 is a view for explaining a region division image arrangement sequence method according to the present invention;

FIG. 7 is a view for explaining a private image grouping method of region division image arrangement sequence according to the present invention; FIG.

8 is a view for explaining a private video grouping variable according to the present invention.

FIG. 9 is a diagram for explaining a maximum repetition period sequencing method of a region division image arrangement sequence according to the present invention; FIG.

10 is a view for explaining a sequence of a closed image and a masking image, a shutter opening and closing sequence, a shutter opening and closing sequence optical response according to the present invention;

FIG. 11 is a diagram illustrating boundary region processing between a closed image and a masking image according to a shutter opening and closing sequence photoresponse according to the present invention; FIG.

12 is a view for explaining an example of the boundary region processing of a closed image and a masking image for light intensity density difference compensation according to the present invention;

FIG. 13 is a view for explaining another example of boundary region processing of a closed image and a masking image for light intensity density difference compensation according to the present invention; FIG.

Claims (20)

delete delete In the method for outputting a private video using a public monitor, Selecting a rule for alternately arranging a private image and a masking image at least two times during one frame of the monitor; Generating a sequence of private images and masking images according to the placement rule; Generating a signal for opening and closing the shutter device in accordance with the image sequence; Outputting the private image and the masking image to the monitor according to the image sequence; Opening and closing the shutter device according to the shutter opening / closing signal Include, The disposition rule selecting step may cause the M private images smaller than N to be grouped during N frames of the monitor. delete The method of claim 3, wherein The swapping of the private image and the masking image is synchronized with the vertical or horizontal synchronization of the monitor. The method of claim 3, wherein The swapping of the private video and the masking video is asynchronous with the monitor and synchronized with data synchronization. The method of claim 3, wherein And the shutter opening and closing sequence is synchronized with the replacement of the video sequence. The method of claim 3, wherein And a cycle time of the private image and the masking image is variable according to time. The method of claim 3, wherein And a grouping unit consisting of the N monitor frames and the M private images is variable over time. The method of claim 3, wherein The grouping unit consisting of the N monitor frames and the M private images is fixed, and the number of the private images and the masking images arranged during one frame of the monitor is variable. The method of claim 10, And a region dividing boundary point formed by disposing the private image and the masking image during one frame of the monitor, coinciding with the grouping units. In the method for outputting a private video using a public monitor, Selecting a rule for alternately arranging a private image and a masking image at least two times during one frame of the monitor; Generating a sequence of private images and masking images according to the placement rule; Generating a signal for opening and closing the shutter device in accordance with the image sequence; Outputting the private image and the masking image to the monitor according to the image sequence pattern; Opening and closing the shutter device according to the shutter opening / closing signal, A masking image having different characteristics for each region of the monitor is output. The disposition rule selecting step may cause the M private images smaller than N to be grouped during N frames of the monitor. delete The method of claim 12, The arranging rule selecting step includes disposing the masked image and the masked image to output a masking image having a strong masking effect in the middle region of the monitor and to output a masking image having a weak masking effect in the upper and lower regions of the monitor. The private video output method. The method of claim 14, The selecting of the arrangement rule may include outputting a mixed image of a circular guide image and a disturbing image to an intermediate region of the monitor, and outputting a circular guide image to the upper and lower regions of the monitor. The method of claim 12, The image output step may include outputting a masking image that is quickly updated in the middle region of the monitor, and outputting a masking image that is relatively slowly updated in the upper and lower regions of the monitor. In the method for outputting a private video using a public monitor, Selecting a rule for alternately arranging a private image and a masking image at least two times during one frame of the monitor; Generating a sequence of private images and masking images according to the placement rule; Generating a signal for opening and closing the shutter device in accordance with the image sequence; Outputting the private image and the masking image to the monitor according to the image sequence pattern; Opening and closing the shutter device according to the shutter opening / closing signal, During the response time of the shutter device, a private video or a connected video is output. The disposition rule selecting step may cause the M private images smaller than N to be grouped during N frames of the monitor. delete The method of claim 17, And a start position and an end position of a shutter response time between the monitor frames in which the private images are grouped, and a private image is output during the response time of the shutter device. The method of claim 17, Between the monitor frames in which the private images are grouped, the end position of the shutter response time in the odd-numbered monitor frame and the start position of the shutter response time in the even-numbered monitor frame, and the shutter response time in the odd-numbered monitor frame. And a start position of the same position as an end position of the shutter response time in the even-numbered monitor frame, and a connection image is output during the response time of the shutter device.