对子图像进行局部直方图计算，由最大方差比例阈

值确定方法计算出子图像的最佳阈值。根据局部直方图中波峰数决定是否增强子图像中被最佳

阈值划分出的低灰度区域和高灰度区的对比度。然后对已经选择性对比增强的图像进行边缘检

测。实验证明图像的区域层次更清楚，提取的边缘细节也更丰富。自适应算法则最大限度地突

出了边缘而同时保持了图像中相近灰度级的平滑性和连续性。-Image pairs local histogram calculation by the maximum variance ratio method to calculate the threshold to determine the optimal threshold value sub-image. According to several local histogram peak to decide whether the image enhancer the best threshold value was divided into low and high gray level contrast of gray areas. Then, contrast-enhanced images have been selective edge detection. Experimental results show more clearly the image of the regional level, the edge extraction details are richer. Adaptive algorithm is to maximize the prominence of the edges while maintaining a similar gray-level image smoothness and continuity.