SECURITY DISPLAY SYSTEM Linnet Tomy*1, Namitha

ISSN 2277-2685 IJESR/December 2014/ Vol-4/Issue-12/989-991 Linnet Tomy et al./ International Journal of Engineering & Science Research

SECURITY DISPLAY SYSTEM Linnet Tomy* 1, Namitha TN 1 1Dept. of Computer Science, Jyothi Engineering College, Jyothi Hills, Panjal Road, Vettikkattiri, Cheruthuruthy, Thrissur, Kerala, India. ABSTRACT A information display system based on temporal psychovisual modulation(tpvm) using the interplay of signal processing, optoelectronics and psychophysics. TPVM differs fundamentally, in principle, design, user experience and cost effectiveness, from head-mounted display technology .The system contains high speed display device and a viewing device that are synchronized and interacting with a human visual system. There are two kinds of viewers, those authorized viewers with the viewing devices who can see the secret information and those unauthorized viewers (bystanders) without the viewing devices who only see mask/disguise images. The prototype is built on a 120 Hz LCD screen with synchronized LC shutter glasses that were originally developed for stereoscopic display.

Keywords: Temporal psychovisual modulation, non-negative matrix factorization, Liquid crystal. 1. INTRODUCTION The amount of secret information need to be protected is increasing day by day .But the information displayed on screens from reaching the eyes of unauthorized viewers are less protected. A better solution to information security display using the technology of temporal psychovisual modulation. Since the human visual system cannot detect quick temporal changes above the flicker fusion frequency (about 60 Hz) and yet modern display technologies offer much higher refresh rates. The display device broadcasts out a set of images called atom frames [7]. The atom frames are then weighted by LC shutter based viewing devices that are synchronized with the display before entering the human visual system and integrating into some desired visual signals. Therefore, through different viewing devices, people can see different contents on the same display. 2. SCIENTIFIC PRINCIPLE OF TPVM TPVM exploits a well known phenomenon in psychophysics of vision: the human visual system (HSV) cannot detect quick temporal changes beyond flicker fusion frequency (around 60 Hz ) [5]. The modern digital displays can run at much higher refresh rates, e.g. 120 Hz, 240Hz and beyond. For example, the new light modulators such as the deformable mirror devices and grating light valve devices can lead to very high refresh rate (up to 88k Hz) and spatial resolution for digital projectors; the main stream LCD/ LED technology also achieves 120Hz or 240Hz refresh rate, as demanded by emerging applications of 3D video playback. If the refresh rate of a digital display exceeds the limit of temporal resolution of HSV, then it is possible for HVS to “render” or perceive different images by fusing differently weighed consecutive frames (called atom frames) emitted from the same display. 2.1 Liquid Crystal Shutter Glasses An active shutter 3D system (alternate frrames sequencing,alternate image, AI,alternating field, field sequential or eclipse method) is a technique of displaying stereoscopic 3D images. It works by only presenting the image intended for the left eye while blocking the right eye's view, then presenting the right-eye image while blocking the left eye, and repeating this so rapidly that the interruptions do not interfere with the perceived fusion of the two images into a single 3D image. Modern active shutter 3D systems generally use liquid crystal shutter glasses (also called "LC shutter glasses" or "active shutter glasses"). Each eye's glass contains a liquid crystal layer which has the property of becoming

*Corresponding Author www.ijesr.org 989

Linnet Tomy et al./ International Journal of Engineering & Science Research

opaque when voltage is applied, being otherwise transparent. The glasses are controlled by a timing signal that allows the glasses to alternately block one eye, and then the other, in synchronization with the refresh rate of the screen. The timing synchronization to the video equipment may be achieved via a wired signal, or wirelessly by either an infrared or radio frequency (e.g. Bluetooth, DLP link) transmitter. Active shutter 3D systems are used to present 3D films in some theaters, and they can be used to present 3D images on CRT, plasma, LCD, projectors and other types of video displays[6]. 2.1.1. Active Shutter Glasses This technology has been adopted by most consumer electronics firms like LG, Samsung, Panasonic, etc. With this technology, an HDTV will display one image to your left eye and one image to your right eye. Since the effective frame rate is halved, these HDTVs need to have double the refresh rate of HDTVs (60 Hz). 2.1.2.Passive (OR Polarized) Glasses The display shows two overlapping images and the glasses have polarized lenses. Each lens is polarized so that it can see only one of the two overlapping images. The only drawback is that viewers will need to sit directly in front of the display to get the full 3D effect. If the viewer is sitting on the side, the 3D effects will be less pronounced 2.2 Psychovisual Signal Processing Operations Fig.1 illustrates the principle of temporal psychovisual modulation. A high refresh rate display device broadcasts a set of atomframes. These atom frames ,after being amplitude modulated by the active liguid crystal glasses and obtain the target image [3]. Suppose that y1, y2… yk are the K images to be formed by HSV. These K target images constitute an N *K matrix Y with column k being image yk of N pixels. The signal decomposition Y = XW has to be a non-negative matrix factorization (NMF) [2], where X is an N *M matrix whose columns are M atom frames x1, x2… xmof N pixels to be cyclically displayed at frequency fd , and W is an M *K modulation weighting matrix.

Fig 1: Image formation via temporal psychovisual modulation in visible spectrum 3. DESIGN OF THE SYSTEM Fig.2 shows the diagram of the proposed system. 3D Vision is a stereoscopic gaming kit from Nvidia which consists of liquid crystal shutter glasses and driver software with various degrees of compatibility. It provides the basic environment for the system.Direct3D can [4] control display process. The aim of Direct 3D is to abstract the communication between a graphics application and the graphics hardware drivers [3]. DirectShow provides a common interface for media across various programming languages, and a framework that can render or record media files on demand at the request of the user or developer . MuPDF is a PDF and XPS parsing and rendering engine to be used in the PDF reader application. Crazy Eddie's GUI (CEGUI) system [1] is a graphical user interface C++ library. File selector is a file management system for the applications of image viewer, ebook reader, video player and PDF reader. Texture mapping is a method for adding detail, surface texture or color to a computergenerated graphic or 3D model. The human computer interaction through mouse, keyboard and Kinect are supported.

Linnet Tomy et al./ International Journal of Engineering & Science Research

Fig 2: Diagram of the system 3.1 Glasses And Glasses-Free View The critical flicker frequency is 60 Hz, then the 120 Hz display is able to emit a set of atom frames without causing flashing feeling of the HVS. The view through the LC glasses[4] that is synchronized with the display is called glasses view and the one who view directly on the screen is called the glasses-free view view. Let the display emit the target image frame I in odd time slot and an auxilary signal I’ in even time slot alternatively, the authorized viewers can access the image signal I with the synchronized LC glasses. While, the unauthorized people without the LC glasses will see a mixed signal of I and I’, denoted as M = I+I’. To prevent those unauthorized viewer to get any useful information from the display, we can set the mixed signal as a blank image, e.g. a constant grey screen M = C. Then, the auxiliary signal can then be computed as I’ = M -I = C – I. 3.2 Texture Mapping Texture mapping is the important technology for the implementation of applications of image viewer, video player and PDF reader.. First we create four vertexes to make a rectangle, and calculate the aspect ratio of which is equal to that of the image we want to show. And then we adjust the camera ,so that the rectangle just fills full of the display’s screen. Finally, we will load the image as a texture to the rectangle so as to present the image to the display 4. RESULTS TPVM was proposed as a new information display technology using the interplay of signal processing, optoelectronics and psychophysics. As a new technology of information display, TPVM is a important solution for information security display. The information security display system includes six applications note pad, puzzle game, image viewer, ebook reader, video player and PDF reader. In these applications, unauthorized viewers cannot see the original information being displayed on the screen. While,the unauthorized viewers cannot see the actual information. REFERENCES [1] Crazy eddie’s gui system, [Online]. Available:http://static.cegui.org.uk/docs/current [2] Direct3d,[Online].Available:http://msdn.microsoft.com/enus/library/windows/desktop/bb219837 (v=vs.85). aspx [3] Luna FD. Introduction to 3D Game Programming with Directx 9.0. Wordware Publishing Inc. 2003. [4] Singh J. Software Glass LCD Driver Based on MSP430 MCU. 2013. [5] Patent Application Publication May, 2014. [6] Sim on Baker. 3D Display Technologies. 2012. [7] Wu X, Zhai G. Temporal psychovisual modulation:A new paradigm of information display, Signal Processing Magazine, IEEE 2013;30(1):136–141.