HTRI: High time range imaging

HDRI (High Dynamic Range Imaging) techniques are used to produce dynamic and well-contrasted images of real-world luminance, by capturing several images of the same scene through exposure bracketing. In the same vein, we have developed a new approach to image fusion from a series of photographs of the same scene taken at different timestamps. When compared with HDRI, exposure bracketing at a single timestamp is replaced by timestamp variation disregarding exposure times. Because of the parallel between these two approaches, this technique is called HTRI (High Time Range Imaging), it aims at capturing ephemeral events occurring over a long time period during which a sequence of images is shot.For each pixel location, the most salient colors are privileged in the series of photographs. The choice of the saliency criterion is based on an analysis of the existing admitted definitions of visual attention. In a second stage, a higher priority is assigned to the pixels with high temporal saliency, i.e., which appear very briefly in the sequence, jointly producing spatial and temporal changes of contrast between two successive frames. The proposed algorithm captures all these salient objects in the final image, without introducing a significant amount of noise, and despite the large illumination changes that may occur in the acquisition conditions from one frame to the next. Experiments evaluate the impact of the method parameters, and confirm benefits of HTRI compared to other fusion techniques.