Flags used for image file reading and writing

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 ,   cv::IMREAD_IGNORE_ORIENTATION = 128 }
	Imread flags. More...
enum	cv::ImwriteEXRCompressionFlags {   cv::IMWRITE_EXR_COMPRESSION_NO = 0 ,   cv::IMWRITE_EXR_COMPRESSION_RLE = 1 ,   cv::IMWRITE_EXR_COMPRESSION_ZIPS = 2 ,   cv::IMWRITE_EXR_COMPRESSION_ZIP = 3 ,   cv::IMWRITE_EXR_COMPRESSION_PIZ = 4 ,   cv::IMWRITE_EXR_COMPRESSION_PXR24 = 5 ,   cv::IMWRITE_EXR_COMPRESSION_B44 = 6 ,   cv::IMWRITE_EXR_COMPRESSION_B44A = 7 ,   cv::IMWRITE_EXR_COMPRESSION_DWAA = 8 ,   cv::IMWRITE_EXR_COMPRESSION_DWAB = 9 }
enum	cv::ImwriteEXRTypeFlags {   cv::IMWRITE_EXR_TYPE_HALF = 1 ,   cv::IMWRITE_EXR_TYPE_FLOAT = 2 }
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_JPEG_SAMPLING_FACTOR = 7 ,   cv::IMWRITE_PNG_COMPRESSION = 16 ,   cv::IMWRITE_PNG_STRATEGY = 17 ,   cv::IMWRITE_PNG_BILEVEL = 18 ,   cv::IMWRITE_PXM_BINARY = 32 ,   cv::IMWRITE_EXR_TYPE = (3 << 4) + 0 ,   cv::IMWRITE_EXR_COMPRESSION = (3 << 4) + 1 ,   cv::IMWRITE_EXR_DWA_COMPRESSION_LEVEL = (3 << 4) + 2 ,   cv::IMWRITE_WEBP_QUALITY = 64 ,   cv::IMWRITE_HDR_COMPRESSION = (5 << 4) + 0 ,   cv::IMWRITE_PAM_TUPLETYPE = 128 ,   cv::IMWRITE_TIFF_RESUNIT = 256 ,   cv::IMWRITE_TIFF_XDPI = 257 ,   cv::IMWRITE_TIFF_YDPI = 258 ,   cv::IMWRITE_TIFF_COMPRESSION = 259 ,   cv::IMWRITE_JPEG2000_COMPRESSION_X1000 = 272 ,   cv::IMWRITE_AVIF_QUALITY = 512 ,   cv::IMWRITE_AVIF_DEPTH = 513 ,   cv::IMWRITE_AVIF_SPEED = 514 }
	Imwrite flags. More...
enum	cv::ImwriteHDRCompressionFlags {   cv::IMWRITE_HDR_COMPRESSION_NONE = 0 ,   cv::IMWRITE_HDR_COMPRESSION_RLE = 1 }
	Imwrite HDR specific values for IMWRITE_HDR_COMPRESSION parameter key. More...
enum	cv::ImwriteJPEGSamplingFactorParams {   cv::IMWRITE_JPEG_SAMPLING_FACTOR_411 = 0x411111 ,   cv::IMWRITE_JPEG_SAMPLING_FACTOR_420 = 0x221111 ,   cv::IMWRITE_JPEG_SAMPLING_FACTOR_422 = 0x211111 ,   cv::IMWRITE_JPEG_SAMPLING_FACTOR_440 = 0x121111 ,   cv::IMWRITE_JPEG_SAMPLING_FACTOR_444 = 0x111111 }
enum	cv::ImwritePAMFlags {   cv::IMWRITE_PAM_FORMAT_NULL = 0 ,   cv::IMWRITE_PAM_FORMAT_BLACKANDWHITE = 1 ,   cv::IMWRITE_PAM_FORMAT_GRAYSCALE = 2 ,   cv::IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA = 3 ,   cv::IMWRITE_PAM_FORMAT_RGB = 4 ,   cv::IMWRITE_PAM_FORMAT_RGB_ALPHA = 5 }
	Imwrite PAM specific tupletype flags used to define the 'TUPLETYPE' field of a PAM file. 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...

Detailed Description

Enumeration Type Documentation

ImreadModes

enum cv::ImreadModes

#include <opencv2/imgcodecs.hpp>

Imread flags.

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

ImwriteEXRCompressionFlags

enum cv::ImwriteEXRCompressionFlags

#include <opencv2/imgcodecs.hpp>

Enumerator
IMWRITE_EXR_COMPRESSION_NO	no compression
IMWRITE_EXR_COMPRESSION_RLE	run length encoding
IMWRITE_EXR_COMPRESSION_ZIPS	zlib compression, one scan line at a time
IMWRITE_EXR_COMPRESSION_ZIP	zlib compression, in blocks of 16 scan lines
IMWRITE_EXR_COMPRESSION_PIZ	piz-based wavelet compression
IMWRITE_EXR_COMPRESSION_PXR24	lossy 24-bit float compression
IMWRITE_EXR_COMPRESSION_B44	lossy 4-by-4 pixel block compression, fixed compression rate
IMWRITE_EXR_COMPRESSION_B44A	lossy 4-by-4 pixel block compression, flat fields are compressed more
IMWRITE_EXR_COMPRESSION_DWAA	lossy DCT based compression, in blocks of 32 scanlines. More efficient for partial buffer access. Supported since OpenEXR 2.2.0.
IMWRITE_EXR_COMPRESSION_DWAB	lossy DCT based compression, in blocks of 256 scanlines. More efficient space wise and faster to decode full frames than DWAA_COMPRESSION. Supported since OpenEXR 2.2.0.

ImwriteEXRTypeFlags

enum cv::ImwriteEXRTypeFlags

#include <opencv2/imgcodecs.hpp>

Enumerator
IMWRITE_EXR_TYPE_HALF	store as HALF (FP16)
IMWRITE_EXR_TYPE_FLOAT	store as FP32 (default)

ImwriteFlags

enum cv::ImwriteFlags

#include <opencv2/imgcodecs.hpp>

Imwrite flags.

Enumerator
IMWRITE_JPEG_QUALITY	For JPEG, it can be a quality from 0 to 100 (the higher is the better). Default value is 95.
IMWRITE_JPEG_PROGRESSIVE	Enable JPEG features, 0 or 1, default is False.
IMWRITE_JPEG_OPTIMIZE	Enable JPEG features, 0 or 1, default is False.
IMWRITE_JPEG_RST_INTERVAL	JPEG restart interval, 0 - 65535, default is 0 - no restart.
IMWRITE_JPEG_LUMA_QUALITY	Separate luma quality level, 0 - 100, default is -1 - don't use.
IMWRITE_JPEG_CHROMA_QUALITY	Separate chroma quality level, 0 - 100, default is -1 - don't use.
IMWRITE_JPEG_SAMPLING_FACTOR	For JPEG, set sampling factor. See cv::ImwriteJPEGSamplingFactorParams.
IMWRITE_PNG_COMPRESSION	For PNG, it can be the compression level from 0 to 9. A higher value means a smaller size and longer compression time. If specified, strategy is changed to IMWRITE_PNG_STRATEGY_DEFAULT (Z_DEFAULT_STRATEGY). Default value is 1 (best speed setting).
IMWRITE_PNG_STRATEGY	One of cv::ImwritePNGFlags, default is IMWRITE_PNG_STRATEGY_RLE.
IMWRITE_PNG_BILEVEL	Binary level PNG, 0 or 1, default is 0.
IMWRITE_PXM_BINARY	For PPM, PGM, or PBM, it can be a binary format flag, 0 or 1. Default value is 1.
IMWRITE_EXR_TYPE	override EXR storage type (FLOAT (FP32) is default)
IMWRITE_EXR_COMPRESSION	override EXR compression type (ZIP_COMPRESSION = 3 is default)
IMWRITE_EXR_DWA_COMPRESSION_LEVEL	override EXR DWA compression level (45 is default)
IMWRITE_WEBP_QUALITY	For WEBP, it can be a quality from 1 to 100 (the higher is the better). By default (without any parameter) and for quality above 100 the lossless compression is used.
IMWRITE_HDR_COMPRESSION	specify HDR compression
IMWRITE_PAM_TUPLETYPE	For PAM, sets the TUPLETYPE field to the corresponding string value that is defined for the format.
IMWRITE_TIFF_RESUNIT	For TIFF, use to specify which DPI resolution unit to set; see libtiff documentation for valid values.
IMWRITE_TIFF_XDPI	For TIFF, use to specify the X direction DPI.
IMWRITE_TIFF_YDPI	For TIFF, use to specify the Y direction DPI.
IMWRITE_TIFF_COMPRESSION	For TIFF, use to specify the image compression scheme. See libtiff for integer constants corresponding to compression formats. Note, for images whose depth is CV_32F, only libtiff's SGILOG compression scheme is used. For other supported depths, the compression scheme can be specified by this flag; LZW compression is the default.
IMWRITE_JPEG2000_COMPRESSION_X1000	For JPEG2000, use to specify the target compression rate (multiplied by 1000). The value can be from 0 to 1000. Default is 1000.
IMWRITE_AVIF_QUALITY	For AVIF, it can be a quality between 0 and 100 (the higher the better). Default is 95.
IMWRITE_AVIF_DEPTH	For AVIF, it can be 8, 10 or 12. If >8, it is stored/read as CV_32F. Default is 8.
IMWRITE_AVIF_SPEED	For AVIF, it is between 0 (slowest) and (fastest). Default is 9.

ImwriteHDRCompressionFlags

enum cv::ImwriteHDRCompressionFlags

#include <opencv2/imgcodecs.hpp>

Imwrite HDR specific values for IMWRITE_HDR_COMPRESSION parameter key.

Enumerator
IMWRITE_HDR_COMPRESSION_NONE
IMWRITE_HDR_COMPRESSION_RLE

ImwriteJPEGSamplingFactorParams

enum cv::ImwriteJPEGSamplingFactorParams

#include <opencv2/imgcodecs.hpp>

Enumerator
IMWRITE_JPEG_SAMPLING_FACTOR_411	4x1,1x1,1x1
IMWRITE_JPEG_SAMPLING_FACTOR_420	2x2,1x1,1x1(Default)
IMWRITE_JPEG_SAMPLING_FACTOR_422	2x1,1x1,1x1
IMWRITE_JPEG_SAMPLING_FACTOR_440	1x2,1x1,1x1
IMWRITE_JPEG_SAMPLING_FACTOR_444	1x1,1x1,1x1(No subsampling)

ImwritePAMFlags

enum cv::ImwritePAMFlags

#include <opencv2/imgcodecs.hpp>

Imwrite PAM specific tupletype flags used to define the 'TUPLETYPE' field of a PAM file.

Enumerator
IMWRITE_PAM_FORMAT_NULL
IMWRITE_PAM_FORMAT_BLACKANDWHITE
IMWRITE_PAM_FORMAT_GRAYSCALE
IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA
IMWRITE_PAM_FORMAT_RGB
IMWRITE_PAM_FORMAT_RGB_ALPHA

ImwritePNGFlags

enum cv::ImwritePNGFlags

#include <opencv2/imgcodecs.hpp>

Imwrite PNG specific flags used to tune the compression algorithm.

These flags will be modify the way of PNG image compression and will be passed to the underlying zlib processing stage.

• The effect of IMWRITE_PNG_STRATEGY_FILTERED is to force more Huffman coding and less string matching; it is somewhat intermediate between IMWRITE_PNG_STRATEGY_DEFAULT and IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY.
• IMWRITE_PNG_STRATEGY_RLE is designed to be almost as fast as IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY, but give better compression for PNG image data.
• The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately.
• IMWRITE_PNG_STRATEGY_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.

Enumerator
IMWRITE_PNG_STRATEGY_DEFAULT	Use this value for normal data.
IMWRITE_PNG_STRATEGY_FILTERED	Use this value for data produced by a filter (or predictor).Filtered data consists mostly of small values with a somewhat random distribution. In this case, the compression algorithm is tuned to compress them better.
IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY	Use this value to force Huffman encoding only (no string match).
IMWRITE_PNG_STRATEGY_RLE	Use this value to limit match distances to one (run-length encoding).
IMWRITE_PNG_STRATEGY_FIXED	Using this value prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.