Subjectively optimised multi-exposure and multi-focus image fusion with compensation for camera shake

Multi-exposure image fusion algorithms are used for enhancing the perceptual quality of an image captured by sensors of limited dynamic range. This is achieved by rendering a single scene based on multiple images captured at different exposure times. Similarly, multi-focus image fusion is used when the limited depth of focus on a selected focus setting of a camera results in parts of an image being out of focus. The solution adopted is to fuse together a number of multi-focus images to create an image that is focused throughout. In this paper we propose a single algorithm that can perform both multi-focus and multi-exposure image fusion. This algorithm is a novel approach in which a set of unregistered multiexposure/focus images is first registered before being fused. The registration of images is done via identifying matching key points in constituent images using Scale Invariant Feature Transforms (SIFT). The RANdom SAmple Consensus (RANSAC) algorithm is used to identify inliers of SIFT key points removing outliers that can cause errors in the registration process. Finally we use the Coherent Point Drift algorithm to register the images, preparing them to be fused in the subsequent fusion stage. For the fusion of images, a novel approach based on an improved version of a Wavelet Based Contourlet Transform (WBCT) is used. The experimental results as follows prove that the proposed algorithm is capable of producing HDR, or multi-focus images by registering and fusing a set of multi-exposure or multi-focus images taken in the presence of camera shake.