编写实现最优阈值方法。假设目标和背景的分布为高斯分布。程序的输入参数根据公式要求而定。将得到的值作为程序输入的参数，对图像进行分割。-Preparation methods to achieve the optimal threshold. The assumption that the distribution of the target and background for the Gaussian distribution. Procedures in accordance with th