图像阈值分割的C++实现，能够自动计算图像阈值，没有图片大小的限制。并且封装位子函数类型，可直接调用。测试性能优秀。(Automatically calculate the image threshold on the C++ platform, and there is no limit of the size of the image. And encapsulate the type of the bit function, which can be called directly. The test performance is excellent.)