The Research On Methods Of Multi-focus Image Fusion

With the development of imaging sensors, more and more digital image processing technologies are applied to some fields. It is difficult or impossible to make all the objects focused in the same scene. How to fuse the objects in order to make all the objects focused in the fused image becomes imminent. Firstly, the fundamental concept, methods and applications of image fusion are introduced and the objective evaluation of the fusion results also discussed in this paper.Then the thesis concentrated on the algorithms of multi-focus image fusion. Firstly the multi-focus image fusion algorithm using adaptive blocking is proposed. Two spatially registered images with different focuses are divided into several blocks. Then the clarity level of every block is calculated. Finally blocks are fused and adaptive divided according to some rule. This method can also get good results even the source images haven't registered or the object moved or the image sensor moved.The fusion method based discrete wavelet transform (DWT) is also discussed. DWT is sensitivity to shift variant signal which means that a simple integer shift of the input signal will usually result in a nontrivial modification of the decomposed coefficients. Thus an image fusion scheme based on the discrete wavelet transform will also be shift dependent, which is undesirable in practical image fusion process. Discrete wavelet frame transform (DWFT) are used to multi-focus image fusion. The fusion process such as activity level measurement, coefficient combination methods and decomposition depth are discussed in detail. Experimental results show that the fusion method using DWFT is better than DWT based.