1.absdiff用法
absdiff函数用于计算两个输入图像之间每个像素的差异，并返回结果图像。
void cv::absdiff ( InputArray src1,
InputArray src2,
OutputArray dst
)
//eg：比较两图像的差异
/*
cv::Mat diff;
cv::absdiff(depLeft32, imDepth, diff);
*/2.ERROR:
terminate called after throwing an instance of 'cv::Exception'
what(): OpenCV(4.2.0) ../modules/core/src/arithm.cpp:666: error: (-209:Sizes of input arguments do not match) The operation is neither 'array op array' (where arrays have the same size and the same number of channels), nor 'array op scalar', nor 'scalar op array' in function 'arithm_op'
错误提示输入的两个矩阵应该有同样的大小和通道，所以把图像的大小打印出来。
cout << "depLeft32 info :" << depLeft32.rows << " " << depLeft32.cols << " " << depLeft32.channels() << endl;
cout << "imDepth info :" << imDepth.rows << " " << imDepth.cols << " " << imDepth.channels() << endl;
//.rows是输出图像的行，.cols是输出图像的列，.channels是输出图像的通道
发现图像大小是一样的，但是通道数不一样，使用cv::cvtColor()将通道数转换为一样
//将三通道转换为单通道
cv::cvtColor(depLeft, depLeft, cv::COLOR_BGR2GRAY);
//将单通道转换为三通道则使用GRAY2BGR、GRAY2RGB、、、
