功能：读入图像文件，做图像反转，然后显示图像在屏幕上-Function: read into the image file, making the image reversal, and then displays the image on the screen

1.图像反转 2.灰度线性变换 3.非线性变换 4.直方图均衡化 5.线性平滑滤波器 6.中值滤波器 8.梯度算子检测边缘 9.LOG算子检测边缘 10.Canny算子检测边缘 11.边界跟踪（bwtraceboundary函数） -Image reversal. Grayscale linear transform 3. Nonlinear transformation 4. Histogram equalization 5 linear smoothi