Boundary finding based multi-focus image fusion through multi-scale morphological focus-measure

Multi-focus image fusion aims to extract the focused regions from multiple partially focused images of the same scene and then combine them together to produce a completely focused image. Detecting the focused regions from multiple images is key for multi-focus image fusion. In this paper, we propose a novel boundary finding based multi-focus image fusion algorithm, in which the task of detecting the focused regions is treated as finding the boundaries between the focused and defocused regions from the source images. According to the found boundaries, the source images could be naturally separated into regions with the same focus conditions, i.e., each region is fully focused or defocused. Then, the focused regions can be found out by selecting the regions with greater focus-measures from each pair of regions. To improve the precision of boundary detection and focused region detection, we also present a multi-scale morphological focus-measure, effectiveness of which has been verified by using some quantitative evaluations. Different from the general multi-focus image fusion algorithms, our algorithm fuses the boundary regions and non-boundary regions of the source images respectively, which helps produce a fusion image with good visual quality. Moreover, the experimental results validate that the proposed algorithm outperforms some state-of-the-art image fusion algorithms in both qualitative and quantitative evaluations.