Full-color holographic waveguide display usually adopts a single-plate display structure, and although the structure is simple and light, the field of view is small. As to this problem, a full-color holographic waveguide display with double-layer grating and double-plate structure is proposed. This configuration consists of four gratings to realize the light input and output, and expension of the exit pupil.To display the RGB color with a better uniformity in the wider field of view, with the Rigorous Coupled-wave Analysis(RCWA), the shape of grating and grating films are designed and optimized.
Waveguide holograms’ diffraction properties include peak-wavelength and diffraction efficiency, which play important role in determine their display performance. Based on the record and reconstruction theory of reflection waveguide holograms, a novel experimental method for testing diffraction properties is introduced and analyzed in this paper. An experiment is implemented and the result indicated that the measured value corresponds well with the designed value.
To overcome the difficulty in segmenting moving objects from a video sequence taken by a freely moving camera, we propose a new segmentation cue based on a joint spatial-color representation for the foreground and background appearances. Given the segmentation result in the previous frame, two sample sets can be extracted for foreground and background, respectively. We transform the spatial locations of the samples in the two sets towards the current frame, then use these transformed samples to evaluate the foreground and background likelihood maps, and combine these maps to form a likelihood ratio map which is further exploited as a segmentation cue and integrated into a conditional random field energy function. The total conditional random field energy is minimized by the graph cut, leading to a binary mask of moving objects for each video frame. We validate the proposed segmentation cue using several video sequences taken by hand-held cameras in outdoor urban scenes and the results show the effiency of the segmentation cue.