Image Render-Capture Applications

May 25, 2010
Bob Ulichney | HP Labs

Two very different applications that use a render-capture paradigm will be presented; the first is a projector-camera system and the second uses a print-scan process.

In anticipation of the proliferation of micro-projectors on handheld imaging devices, we designed and tested a projector-camera system that allows a distant user to point into a remote 3D environment with a projector. The solution involves a means for locating a projected dot, and for adjusting its location to correspond to a position indicted by a remote user viewing the scene through a camera. While many projector-camera systems require a calibration phase, our solution allows calibration-free operation. The tracking algorithm is implemented with a modified 2D gradient decent method that performs even in the presence of spatial discontinuities. Our prototype performs real-time and accurate tracking across irregularly shaped and colored surfaces. Tests with Inter-continental separations of client and server suffered no loss of responsiveness.

An alternative to unsightly barcodes is a new method for embedding data into an image halftone. The process takes as input any image and a payload of data to be encoded and produces a bitonal clustered-dot halftone of that image with selected halftone clusters shifted to carry varying number of bits from the payload. The resulting data-bearing steganographic halftone is referred to as a “Stegatone”. Because of the small size and large number of clustered-dot cells in printed halftones the bit density is quite high. Scans of printed Stegatones from a number of printers support the robustness of the method with high data recovery rates.

Speaker Details

Robert Ulichney received a Ph.D. from MIT in electrical engineering and computer science. His research career began at Digital Equipment Corp. where he focused on image and video implementations for both hard copy and display products. From 1998-2002 he was with Compaq’s Cambridge Research Lab where he led a number of research efforts in video and image processing. Bob is currently a Distinguished Technologist with HP Labs where research activities have included image enhancement, photo red-eye correction, and steganographic halftoning. His publications and patents can be downloaded from ulichney.org.