Abstract: To address the problem of edge blurring in traditional space domain fusion of multi-focus images, a multi-focus image fusion method based on Guided Filtering (GF) and difference image was proposed. Firstly, the source images were filtered by GF in different levels, and the difference was performed to the filtered images, so as to obtain the focused feature map. Secondly, the Energy of Gradient (EOG) of the focused feature map was used to obtain initial decision map. And to remove the noisy pixels caused by similar HOG, the spatial consistency verification and morphological operation were performed to initial decision map. Thirdly, to avoid sudden change of image feature, the initial decision map was optimized by GF. Finally, weighted fusion was performed to source images based on the optimized decision map, so as to obtain the fusion image. Three sets of classic multi-focus images were selected as experimental images, and the results obtained by the proposed method and other 9 multi-focus image fusion methods were compared. The subjective visual effects showed that the proposed method was able to better preserve the detailed information of multi-focus images, and four objective evaluation indicators of images processed by the proposed method were significantly better than those of the images processed by comparison methods. Experimental results show that the proposed method can achieve high-quality fusion image, well preserve information in source images, effectively solve edge blurring problem of traditional multi-focus image fusion.

Key words: multi-focus image fusion, Guided Filter (GF), difference image, decision map, spatial consistency

摘要： 针对传统的多聚焦图像的空间域融合容易出现边缘模糊的问题，提出了一种基于引导滤波（GF）和差分图像的多聚焦图像融合方法。首先，将源图像进行不同水平的GF，并对滤波后图像进行差分，从而获得聚焦特征图像；随后，利用聚焦特征图像的梯度能量（EOG）信息获得初始决策图，对初始决策图进行空间一致性检查以及形态学操作以消除因EOG相近而造成的噪点；然后，对初始决策图进行GF以得到优化后决策图，从而避免融合后的图像存在边缘骤变的问题；最后，基于优化后决策图对源图像进行加权融合，以得到融合图像。选取3组经典的多聚焦图像作为实验图像，将所提方法与其他9种多聚焦图像融合方法得到的结果进行比较。主观视觉效果显示，所提方法能更好地将多聚焦图像的细节信息保存下来，另外，经该方法处理后的图像的4项客观评价指标均显著优于对比方法。结果表明，所提方法能够获得高质量的融合图像，较好地保留原始图像信息，有效解决传统多聚焦图像融合出现的边缘模糊问题。

关键词: 多聚焦图像融合, 引导滤波, 差分图像, 决策图, 空间一致性