在矩阵中使用的数据类型是double。因此可以通过语句I2=im2double(I1) 把图像数组I1转换成double精度类型；如果不转换，在对uint8进行加减时会产生溢出，可能提示的错误为：Function * is not defined for values of class uint8 -The data used in the matrix type is double. So you can statement I2 = im2double (I1)　converting the image into an array of double precision type I1　if you do not convert on uint8 addition and subtraction will produce an overflow, possibly suggesting that the error is: Function ' *'　is not defined for values ​ ​ of class ' uint8'