https://docs.huihoo.com/opencv/3.0/d4/da8/group__imgcodecs.html

Enumerations
enum  	cv::ImreadModes {
    
    
  cv::IMREAD_UNCHANGED = -1,
  cv::IMREAD_GRAYSCALE = 0,
  cv::IMREAD_COLOR = 1,
  cv::IMREAD_ANYDEPTH = 2,
  cv::IMREAD_ANYCOLOR = 4,
  cv::IMREAD_LOAD_GDAL = 8,
  cv::IMREAD_REDUCED_GRAYSCALE_2 = 16,
  cv::IMREAD_REDUCED_COLOR_2 = 17,
  cv::IMREAD_REDUCED_GRAYSCALE_4 = 32,
  cv::IMREAD_REDUCED_COLOR_4 = 33,
  cv::IMREAD_REDUCED_GRAYSCALE_8 = 64,
  cv::IMREAD_REDUCED_COLOR_8 = 65
}
 	Imread flags. More...
 
enum  	cv::ImwriteFlags {
    
    
  cv::IMWRITE_JPEG_QUALITY = 1,
  cv::IMWRITE_JPEG_PROGRESSIVE = 2,
  cv::IMWRITE_JPEG_OPTIMIZE = 3,
  cv::IMWRITE_JPEG_RST_INTERVAL = 4,
  cv::IMWRITE_JPEG_LUMA_QUALITY = 5,
  cv::IMWRITE_JPEG_CHROMA_QUALITY = 6,
  cv::IMWRITE_PNG_COMPRESSION = 16,
  cv::IMWRITE_PNG_STRATEGY = 17,
  cv::IMWRITE_PNG_BILEVEL = 18,
  cv::IMWRITE_PXM_BINARY = 32,
  cv::IMWRITE_WEBP_QUALITY = 64
}
 	Imwrite flags. More...
 
enum  	cv::ImwritePNGFlags {
    
    
  cv::IMWRITE_PNG_STRATEGY_DEFAULT = 0,
  cv::IMWRITE_PNG_STRATEGY_FILTERED = 1,
  cv::IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY = 2,
  cv::IMWRITE_PNG_STRATEGY_RLE = 3,
  cv::IMWRITE_PNG_STRATEGY_FIXED = 4
}
 	Imwrite PNG specific flags used to tune the compression algorithm. More...