The hand vein image tends to be of low contrast, which affects the recognition accuracy of the whole hand vein recognition system. The effective area of the hand vein image was extracted firstly and then the Histogram Equalization (HE) algorithm and its improved versions were employed to enhance the contrast of the extracted hand vein image. The results-indicate that the Partially Overlapped Sub-block Histogram Equalization (POSHE) can enhance not only the overall contrast but also the detailed one. Meanwhile, its high efficiency is suitable to the hand vein image contrast enhancement.%手背静脉图像对比度往往较低,这将影响整个手背静脉识别系统的识别准确率.首先提取手背静脉图像中的有效区域,然后利用直方图均衡化(HE)及其各种改进算法对提取的手背静脉图像进行对比度增强处理.实验结果表明,子块部分重叠局部直方图均衡化算法(POSHE)不但能够增强图像的整体对比度,而且图像中细节与背景之间的对比度也得到了增强,同时该算法效率较高,适合于手背静脉图像的对比度增强处理.
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