在opencv的环境下，测试图像预处理结果，亮点是测试了对灰度图先进行形态学处理再阈值分割和先阈值分割再形态学的区别。-Opencv environment in the test image pre-processing the results, highlight the first test for morphological processing of gray-scale thresholding and then thresholding again before morpholog

创建一个程序读入并显示一幅图像，运行用户在图像中选择一个矩形区域，然后通过按住鼠标按键画一个矩形，当鼠标键放开，高亮显示矩形框。-Create a program that reads and displays an image, run user select a rectangular area in the image, and then hold down the mouse button, draw a rectangle, release the mouse button, the