  In this paper, we present a fast yet effective method for pixel-level
scale-invariant image fusion in spatial domain based on the scale-space theory.
Specifically, we propose a scale-invariant structure saliency selection scheme
based on the difference-of-Gaussian (DoG) pyramid of images to build the
weights or activity map. Due to the scale-invariant structure saliency
selection, our method can keep both details of small size objects and the
integrity information of large size objects in images. In addition, our method
is very efficient since there are no complex operation involved and easy to be
implemented and therefore can be used for fast high resolution images fusion.
Experimental results demonstrate the proposed method yields competitive or even
better results comparing to state-of-the-art image fusion methods both in terms
of visual quality and objective evaluation metrics. Furthermore, the proposed
method is very fast and can be used to fuse the high resolution images in
real-time. Code is available at https://github.com/yiqingmy/Fusion.
