2x3D: Real-Time Shader for Simultaneous 2D/3D Hybrid Theater Wataru FUJIMURA * Yukua KOIDE Robert SONGER † Takahiro HAYAKAWA Akihiko SHIRAI ‡ Kazuhisa YANAKA Kanagawa Institute of Technology Abstract 2x3D is a simultaneous 2D/3D hybrid theater and its real-time shader for image hiding. In this project, 2x3D concealment pro- cessing is performed using a pixel shader to support the hiding of dynamic motion pictures in real time. In this way, multiplex-hidden images are possible with multiple videos in real-time and stereo- scopic 3D can be achieved. 2x3D method does not require any electronic devices such as active shutter glasses for viewers’ side, and it reduces the number of required screens and cost of glasses overall. As an experiment, a stereoscopic 3D left-eye image is shown as the 2D image for viewing with the naked eye while the right-eye image can be seen through a polarized filter. In this way, audience members can experience a stereoscopic effect by placing a filter over the right eye only. A difference in brightness exists between the two images, but this is not a problem for depth per- ception as in the anaglyph method. Not only is this 2D/3D hybrid theater cost-effective for cinemas, it can provide a universal design that accounts for the hazards posed by stereoscopic 3D glasses for children, the stereo blind, and people whose eyes fatigue easily or who already wear glasses. CR Categories: I.3.3 [Computer Graphics]: Picture/Image Generation—Display Algorithms I.3.1 [Computer Graphics]: Hardware Architecture—Parallel processing, Three-dimensional displays; Keywords: stereoscopic 3D, multiplex, hidden imaging 1 Motivation In recent years, stereoscopic displays paired with glasses that make 3D movies possible are a popular research topic and continue to become widespread. These stereoscopic displays can create the ap- pearance of three-dimensional images by simply wearing a pair of special glasses; however, when seen with the naked eye, the images for the left and right eyes can be seen overlapping. Therefore, a method has been developed for viewing both 2D and 3D images simultaneously on one screen, called “2x3D Real-Time Shader”. With this technique, it is no longer necessary to screen 2D and 3D movies separately, reducing the number of required screens overall. Figure 1: ”2x3D” is a 2D/3D Hybrid Theater and glasses. A par- allax effect results from both glasses and the naked eye (left). Some techniques already exist for the given context. “Thirdeye” ∗ e-mail:2x3d@shirai.la † Kanazawa Technical College ‡ e-mail:shirai@mail.com [Mistry 2009] enabled multiple viewers to see different content on a single display using shutter glasses. A similar idea has also been produced by SONY as “SimulView”. These techniques are differ- ent from ours because they produce a doubled image when the user views the displays without glasses. “Snared Illumination” [McDowall et al. 2004] seems to be a pi- oneer of the display in which both an image for naked eyes and a hidden image can be provided simultaneously by using glasses with active shutters. Although this idea might be applicabe to our 2D/3D compatible display, glasses which are lighter, more inexpensive and batteryless are more desirable for our application. 2 Core Technologies 2.1 Past Research: ScritterH A system for projecting multiple images on a single screen through multiplexing, called ”Scritter”, has been developed by Nagano and Utsugi and associates [Koki. N. and N. 2010] [Nagano et al. 2011]. ScritterH uses two projectors to compose a naked-eye image (im- age A) through the polarized projection of a hidden image (image B) and its difference with the naked-eye image (image C) onto a screen. Image A is visible with the naked eye while image B is vis- ible only to users wearing polarized glasses. However, gamma values should be taken into account in order to achieve full concealment. Additionally, the ScritterH technique did not have support for dynamic images. Although a method was pro- posed for viewing both 2D and 3D images simultaneously on one screen [Shirai Akihiko 2012], only an experimental system which can treat only still images was made. 2.2 Gamma Correction Algorithm A concealment processing technique has been developed to support the hiding of dynamic images using a pixel shader. First, arbitrary images A and B (with respective pixel luminance values a and b) are defined where A is the naked-eye image and B is the hidden image. Here the respective pixel luminance for the naked-eye image and hidden image a and b are given values in the range of 0 - 255. a ′ = a × 255 - a min 255 + a min (1) b ′ = b × a min 255 (2) Where a min is the minimum value of a ′ , which is set to 128 as the middle value of a 256 gradient in the case that gamma is not taken into consideration, or in the case that gamma is taken into consider- ation, it can be used for contrast reduction of the same levels as A and B by setting it to the middle value of the output luminance. c = ( a ′γ - b ′γ ) 1 γ (3) γ is the gamma value for the projector and is set to 2.2 by default.