3,235 research outputs found

    Discovering salient objects from videos using spatiotemporal salient region detection

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    Detecting salient objects from images and videos has many useful applications in computer vision. In this paper, a novel spatiotemporal salient region detection approach is proposed. The proposed approach computes spatiotemporal saliency by estimating spatial and temporal saliencies separately. The spatial saliency of an image is computed by estimating the color contrast cue and color distribution cue. The estimations of these cues exploit the patch level and region level image abstractions in a unified way. The aforementioned cues are fused to compute an initial spatial saliency map, which is further refined to emphasize saliencies of objects uniformly, and to suppress saliencies of background noises. The final spatial saliency map is computed by integrating the refined saliency map with center prior map. The temporal saliency is computed based on local and global temporal saliencies estimations using patch level optical flow abstractions. Both local and global temporal saliencies are fused to compute the temporal saliency. Finally, spatial and temporal saliencies are integrated to generate a spatiotemporal saliency map. The proposed temporal and spatiotemporal salient region detection approaches are extensively experimented on challenging salient object detection video datasets. The experimental results show that the proposed approaches achieve an improved performance than several state-of-the-art saliency detection approaches. In order to compensate different needs in respect of the speed/accuracy tradeoff, faster variants of the spatial, temporal and spatiotemporal salient region detection approaches are also presented in this paper

    Excitation Backprop for RNNs

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    Deep models are state-of-the-art for many vision tasks including video action recognition and video captioning. Models are trained to caption or classify activity in videos, but little is known about the evidence used to make such decisions. Grounding decisions made by deep networks has been studied in spatial visual content, giving more insight into model predictions for images. However, such studies are relatively lacking for models of spatiotemporal visual content - videos. In this work, we devise a formulation that simultaneously grounds evidence in space and time, in a single pass, using top-down saliency. We visualize the spatiotemporal cues that contribute to a deep model's classification/captioning output using the model's internal representation. Based on these spatiotemporal cues, we are able to localize segments within a video that correspond with a specific action, or phrase from a caption, without explicitly optimizing/training for these tasks.Comment: CVPR 2018 Camera Ready Versio
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