opencv基础操作
- 图像读取显示

opencv基础操作

图像读取显示

读取图像

Mat imread( const String& filename, int flags = IMREAD_COLOR ):读取图像，返回Mat实例参数：

flags:图像读取模式,

 enum ImreadModes {
 IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped). Ignore EXIF orientation.
 IMREAD_GRAYSCALE            = 0,  //!< If set, always convert image to the single channel grayscale image (codec internal conversion).
 IMREAD_COLOR                = 1,  //!< If set, always convert image to the 3 channel BGR color image.
 IMREAD_ANYDEPTH             = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
 IMREAD_ANYCOLOR             = 4,  //!< If set, the image is read in any possible color format.
 IMREAD_LOAD_GDAL            = 8,  //!< If set, use the gdal driver for loading the image.
 IMREAD_REDUCED_GRAYSCALE_2  = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.
 IMREAD_REDUCED_COLOR_2      = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.
 IMREAD_REDUCED_GRAYSCALE_4  = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.
 IMREAD_REDUCED_COLOR_4      = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.
 IMREAD_REDUCED_GRAYSCALE_8  = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.
 IMREAD_REDUCED_COLOR_8      = 65, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.
 IMREAD_IGNORE_ORIENTATION   = 128 //!< If set, do not rotate the image according to EXIF's orientation flag.
  };

显示图像

void imshow(const String& winname, InputArray mat):显示图像
- winname:窗口标题
- mat:要显示的图像

创建窗口

namedWindow(const String& winname, int flags = WINDOW_AUTOSIZE):创建一个命名窗口

winname:窗口标题

flags:创建窗口的类型

enum WindowFlags {
  WINDOW_NORMAL     = 0x00000000, //!< the user can resize the window (no constraint) / also use to switch a fullscreen window to a normal size.
  WINDOW_AUTOSIZE   = 0x00000001, //!< the user cannot resize the window, the size is constrainted by the image displayed.
  WINDOW_OPENGL     = 0x00001000, //!< window with opengl support.

  WINDOW_FULLSCREEN = 1,          //!< change the window to fullscreen.
  WINDOW_FREERATIO  = 0x00000100, //!< the image expends as much as it can (no ratio constraint).
  WINDOW_KEEPRATIO  = 0x00000000, //!< the ratio of the image is respected.
  WINDOW_GUI_EXPANDED=0x00000000, //!< status bar and tool bar
  WINDOW_GUI_NORMAL = 0x00000010, //!< old fashious way
 };

写入图片到文件

bool imwrite( const String& filename, InputArray img,const std::vector<int>& params = std::vector<int>())：写入图片到文件
- filename:图片路径
- img：要写入的图片
- params:特定格式的参数
  - jpg: params代表0-100的图像质量（CV_IMWRITE_JPEG_QUALITY），默认值是95
  - png: params代表压缩级别，从0-9（CV_IMWRITE_PNG_COMPRESSION），较高的值代表更小的尺寸和更长的压缩时间，默认值是3

opencv基础操作

opencv基础操作

图像读取显示

Comments