Image Fusion is the process of combining two or more input images into a single image. The main reason for combining the images is to get a more informative output image. In mobile, dual camera Image Fusion comes into play in several ways: The first is related to a dual camera with one color sensor and another monochromatic sensor (with the Bayer filter removed). The monochromatic sensor captures 2.5 times more light, thus reaches better resolution and SNR. By fusing the images coming from both cameras, the output image has better SNR and resolution, especially in low light conditions.
The second is with a zoom dual camera – a wide field-of-view camera coupled with a telephoto narrow field-of-view camera. In this case, Image Fusion will also improve the SNR and resolution from no zoom up to the point the telephoto camera field-of-view is the dominant one. In the following example images it is easy to see the resolution improvement in the fused image vs the standard digital zoom (images were taken with a 3x optical zoom camera).