Flexible Image Blending for Image Mosaicing with Reduced Artifacts

Image mosaicing involves geometric alignment among video frames and image compositing or blending. For dynamic mosaicing, image mosaics are constructed dynamically along with incoming video frames. Consequently, dynamic mosaicing demands efficient operations for both alignment and blending in order to achieve real-time performance. In this paper, we focus on efficient image blending methods that create good-quality image mosaics from any number of overlapping frames. One of the driving forces for efficient image processing is the huge market of mobile devices such as cell phones, PDAs that have image sensors and processors. In particular, we show that it is possible to have efficient sequential implementations of blending methods that simultaneously involve all accumulated video frames. The choices of image blending include traditional averaging, overlapping and flexible ones that take into consideration temporal order of video frames and user control inputs. In addition, we show that artifacts due to mis-alignment, image intensity difference can be significantly reduced by efficiently applying weighting functions when blending video frames. These weighting functions are based on pixel locations in a frame, view perspective and temporal order of this frame. One interesting application of flexible blending is to visualize moving objects on a mosaiced stationary background. Finally, to correct for significant exposure difference in video frames, we propose a pyramid extension based on intensity matching of aligned images at the coarsest resolution. Our experiments with real image sequences demonstrate the advantages of the proposed methods.