Quick Response (QR) codes are widely used for encoding information accessible via mobile devices. However, since QR codes appear as a complex pattern of black and white modules, it is difficult for users to detect tampering. In this study, we propose a camouflaged QR code attack method utilizing high refresh rate displays. This method rapidly alternates two QR codes above the critical flicker fusion frequency of human vision, so humans perceive a single fused image, whereas cameras may capture either code. Preliminary experiments using LCD displays confirmed that the attack is feasible, but revealed a constraint on module modification due to LCD characteristics. To overcome this limitation, we applied the method to off-the-shelf LED displays and confirmed that the LCD-related constraint was resolved, enabling more flexible code modification with QR codes.

We propose a new telecommunication system using a flexible screen to display head motion gesture. Previous video-based telecommunication systems with a movable display used a flat and solid screen, and their presence was abiotic. On the other hand, traditional animation techniques provide the art of making solid objects appear to "animate". One of the most important principles of the animation techniques is "squash and stretch" that deforms the shape of the object. This technique inspired the proposed system: we employed a flexible screen and deformed it by using four servo motors to represent biotic motion.

We present our new interaction technique for tabletop system and video game application using it. This technique is for recognizing a pinching gesture performed with the thumb and forefinger and tapping gestures with them by a ceiling camera above the table. The positions and orientations of multiple gestures are recognized at 200Hz, and the users around the table are tracked by their arm positions. This technique is useful for large-sized tabletop system for multiple users because it does not require any additional equipments to them nor registration process before using the system. Some pilot studies demonstrated the robustness and accuracy of the proposed technique with displaying appropriate guide on the display. We also developed a video game application called "Pac-pac". A player can shoot a bullet along the orientation of his hand by tapping, from any side of the table. We exhibited Pac-pac several time and well-received.

Tabletop systems are currently being focused on and many applications using these systems are being developed. In such tabletop systems, how to recognize real objects on the table is an essential and important issue. In existing tabletop systems, 2-D markers have been often used. However, their black-and-white pattern, which means nothing to humans, spoils the appearance of the object. We developed transparent markers on a liquid crystal display (LCD) tabletop system by using the polarization features of the LCD and optical lms. In particular, through experiments with various kinds of optical films, we found that two halfwave plates make the markers rotation invariant. By using the transparent markers, tangible transparent Magic Lenses(TM) applications were developed.

PhotoelasticTouch is a novel tabletop system designed to intuitively facilitate touch-based interaction via real objects made from transparent elastic material. The system utilizes vision-based recognition techniques and the photoelastic properties of the transparent rubber to recognize deformed regions of the elastic material. Our system works with elastic materials over a wide variety of shapes and does not require any explicit visual markers. Compared to traditional interactive surfaces, our 2.5 dimensional interface system enables direct touch interaction and soft tactile feedback. In this paper we present our force sensing technique using photoelasticity and describe the implementation of our prototype system. We also present three practical applications of PhotoelasticTouch, a force-sensitive touch panel, a tangible face application, and a paint application.

We introduce an inexpensive position input device called the FieldMouse, with which a computer can tell the position of the device on paper or any flat surface without using special input tablets or position detection devices. A FieldMouse is a combination of an ID recognizer like a barcode reader and a mouse which detects relative movement of the device. Using a FieldMouse, a user first detects an ID on paper by using the barcode reader, and then drags it from the ID using the mouse. If the location of the ID is known, the location of the dragged FieldMouse can also be calculated by adding the amount of movement from the ID to the position of the FieldMouse. Using a FieldMouse in this way, any flat surface can work as a pointing device that supports absolute position input, just by putting an ID tag somewhere on the surface. A FieldMouse can also be used for enabling a graphical user interface (GUI) on paper or on any flat surface by analyzing the direction and the amount of mouse movement after detecting an ID. In this paper, we introduce how a FieldMouse can be used in various situations to enable computing in real-world environments.