error C2664: “T2A”: 不能将参数 1 从“CString”转换为“LPTSTR”

    Mat srcImage;
    CString m_save_path= hFileDlg.GetPathName();  
    m_save_path.Replace(_T("\\"),_T("\\\\"));  
    USES_CONVERSION;  
    //调用函数，T2A和W2A均支持ATL和MFC中的字符转换  
    std::string saveImage(m_save_path.GetBuffer());

    cvSaveImage(W2A(m_save_path),srcImage);  
    UpdateData(FALSE);  

你的工程字符集是什么，如果不是unicode，你需要调用T2A等来进行转换

 A
 ANSI character string.

W
 Unicode character string.

T
 Generic character string (equivalent to W when _UNICODE is defined, equivalent to A otherwise).

OLE
 OLE character string (equivalent to W).

注意字符的表示。。。