中文说明：双峰法是一种简单的阈值分割方法，即如果灰度级直方图呈现明显的双峰状，则选双峰之间的谷底所对应的灰度级作为阈值分割。
English Description：
Bimodal method is a simple threshold segmentation method, that is, if the gray level histogram presents obvious bimodal shape, the gray level corresponding to the valley bottom between the bimodal is selected as the threshold segmentation.