filename     : p_Cot04a.pdf
entry        : inproceedings
conference	 : Third IEEE and ACM International Symposium on Mixed and Augmented Reality (ISMAR'04), November 02 - 05, 2004, Arlington, VA, USA 
pages        : 100-109
year         : 2004
month        : June
title        : Embedding Imperceptible Patterns into Projected Images for Simultaneous Acquisition and Display
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author       : D. Cotting, M. Naef, M. Gross, H. Fuchs
booktitle    : Proceedings of International Symposium on Mixed and Augmented Reality 2004
ISSN/ISBN    : 0-7695-2191-6
editor       : 
publisher    : IEEE Computer Society Press
publ.place   :
volume       :
issue        :
language     : english
keywords     : 
abstract     : We introduce a method to imperceptibly embed arbitrary binary patterns into ordinary color images displayed by unmodified off-the-shelf Digital Light Processing (DLP) projectors. The encoded images are visible only to cameras synchronized with the projectors and exposed for a short interval, while the original images appear only minimally degraded to the human eye. To achieve this goal, we analyze and exploit the micro-mirror modulation pattern used by the projection technology to generate intensity levels for each pixel and color channel. Our real-time embedding process maps the user’s original color image values to the nearest values whose camera-perceived intensities are the ones desired by the binary image to be embedded. The color differences caused by this mapping process are compensated by error-diffusion dithering. The non-intrusive nature of our novel approach allows simultaneous (immersive) display and acquisition under controlled lighting conditions, as defined on a pixel level by the binary patterns. We therefore introduce structured light techniques into human-inhabited mixed and augmented reality environments, where they previously often were too intrusive.