多光谱成像系统将光分成多个光谱通道, 对不同的通道进行单独成像后合成一幅多光谱图像。不同通道的光折射率不同, 造成聚焦清晰位置也不同, 需要对每个通道分别调焦。为解决调焦耗时的问题, 本文基于不同通道间清晰度曲线的相似性, 提出一种快速的自动调焦方法。先选定一个基准通道调焦, 得到清晰度曲线, 对其余通道, 利用清晰度曲线的相似性只需采集少量图像就能求出清晰调焦位置。实验表明, 该算法能快速准确的完成对各个通道的调焦, 效率明显优于已有算法。

A multispectral imaging system acquires spectral color images by splitting the light spectrum into multiple bands. Due to the different refractive index for individual wavelength, the focus positions of the channels are different, and thus each channel should be adjusted to obtain sharp image. We propose a fast autofocus method based on the similarity of focus measure distributions, which is suitable to multispectral imaging. In the proposed method, we first obtain the focus measure distribution of a reference channel using traditional autofocus method. Then, the clear focus positions of other channels are located according to the distribution similarity between individual channels. As only a few images are needed, the autofocus for these channels is quite fast. Experimental results validate that the proposed method performs better than the traditional techniques.