PicWall: Photo collage on-the-fly

Photo collage, which constructs a compact and visually appealing representation from a collection of input images, provides the best convenient and impressive user experience. Previous approaches for automatic collage generation are always analogized as optimization problems, in which the researchers are trying to find the best balance between maximizing the visibility of photos´ salient areas as well as compactly arrange the collage canvas layout. However, automatic saliency detection can sometimes be harmful since we cannot guarantee all of the user´s interest areas are well-kept. On the other hand, the rapid development of mobile technology also calls for a robust solution of fast collage generation without any computation-expensive processes such as saliency detection and graph-cut. The PicWall approach proposed in this paper offers real-time collage generation. Given the expected canvas sizes, it tightly packs the input images while keeping their aspect ratios and orientations unchanged. Experiments show that it costs less than 0.5ms for a 100-photo collage generation. Besides, various PicWall-based applications are also demonstrated.