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42
43#ifndef OPENCV_IMGCODECS_HPP
44#define OPENCV_IMGCODECS_HPP
45
46#include "opencv2/core.hpp"
47
48/**
49 @defgroup imgcodecs Image file reading and writing
50 @{
51 @defgroup imgcodecs_flags Flags used for image file reading and writing
52 @defgroup imgcodecs_ios iOS glue
53 @defgroup imgcodecs_macosx MacOS(OSX) glue
54 @}
55*/
56
57//////////////////////////////// image codec ////////////////////////////////
58namespace cv
59{
60
61//! @addtogroup imgcodecs
62//! @{
63
64//! @addtogroup imgcodecs_flags
65//! @{
66
67//! Imread flags
68enum ImreadModes {
69 IMREAD_UNCHANGED = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped). Ignore EXIF orientation.
70 IMREAD_GRAYSCALE = 0, //!< If set, always convert image to the single channel grayscale image (codec internal conversion).
71 IMREAD_COLOR_BGR = 1, //!< If set, always convert image to the 3 channel BGR color image.
72 IMREAD_COLOR = 1, //!< Same as IMREAD_COLOR_BGR.
73 IMREAD_ANYDEPTH = 2, //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
74 IMREAD_ANYCOLOR = 4, //!< If set, the image is read in any possible color format.
75 IMREAD_LOAD_GDAL = 8, //!< If set, use the gdal driver for loading the image.
76 IMREAD_REDUCED_GRAYSCALE_2 = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.
77 IMREAD_REDUCED_COLOR_2 = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.
78 IMREAD_REDUCED_GRAYSCALE_4 = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.
79 IMREAD_REDUCED_COLOR_4 = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.
80 IMREAD_REDUCED_GRAYSCALE_8 = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.
81 IMREAD_REDUCED_COLOR_8 = 65, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.
82 IMREAD_IGNORE_ORIENTATION = 128, //!< If set, do not rotate the image according to EXIF's orientation flag.
83 IMREAD_COLOR_RGB = 256, //!< If set, always convert image to the 3 channel RGB color image.
84 };
85
86//! Imwrite flags
87enum ImwriteFlags {
88 IMWRITE_JPEG_QUALITY = 1, //!< For JPEG, it can be a quality from 0 to 100 (the higher is the better). Default value is 95.
89 IMWRITE_JPEG_PROGRESSIVE = 2, //!< Enable JPEG features, 0 or 1, default is False.
90 IMWRITE_JPEG_OPTIMIZE = 3, //!< Enable JPEG features, 0 or 1, default is False.
91 IMWRITE_JPEG_RST_INTERVAL = 4, //!< JPEG restart interval, 0 - 65535, default is 0 - no restart.
92 IMWRITE_JPEG_LUMA_QUALITY = 5, //!< Separate luma quality level, 0 - 100, default is -1 - don't use. If JPEG_LIB_VERSION < 70, Not supported.
93 IMWRITE_JPEG_CHROMA_QUALITY = 6, //!< Separate chroma quality level, 0 - 100, default is -1 - don't use. If JPEG_LIB_VERSION < 70, Not supported.
94 IMWRITE_JPEG_SAMPLING_FACTOR = 7, //!< For JPEG, set sampling factor. See cv::ImwriteJPEGSamplingFactorParams.
95 IMWRITE_PNG_COMPRESSION = 16, //!< 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).
96 IMWRITE_PNG_STRATEGY = 17, //!< One of cv::ImwritePNGFlags, default is IMWRITE_PNG_STRATEGY_RLE.
97 IMWRITE_PNG_BILEVEL = 18, //!< Binary level PNG, 0 or 1, default is 0.
98 IMWRITE_PXM_BINARY = 32, //!< For PPM, PGM, or PBM, it can be a binary format flag, 0 or 1. Default value is 1.
99 IMWRITE_EXR_TYPE = (3 << 4) + 0 /* 48 */, //!< override EXR storage type (FLOAT (FP32) is default)
100 IMWRITE_EXR_COMPRESSION = (3 << 4) + 1 /* 49 */, //!< override EXR compression type (ZIP_COMPRESSION = 3 is default)
101 IMWRITE_EXR_DWA_COMPRESSION_LEVEL = (3 << 4) + 2 /* 50 */, //!< override EXR DWA compression level (45 is default)
102 IMWRITE_WEBP_QUALITY = 64, //!< 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.
103 IMWRITE_HDR_COMPRESSION = (5 << 4) + 0 /* 80 */, //!< specify HDR compression
104 IMWRITE_PAM_TUPLETYPE = 128,//!< For PAM, sets the TUPLETYPE field to the corresponding string value that is defined for the format
105 IMWRITE_TIFF_RESUNIT = 256,//!< For TIFF, use to specify which DPI resolution unit to set; see libtiff documentation for valid values
106 IMWRITE_TIFF_XDPI = 257,//!< For TIFF, use to specify the X direction DPI
107 IMWRITE_TIFF_YDPI = 258,//!< For TIFF, use to specify the Y direction DPI
108 IMWRITE_TIFF_COMPRESSION = 259,//!< For TIFF, use to specify the image compression scheme. See cv::ImwriteTiffCompressionFlags. 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.
109 IMWRITE_TIFF_ROWSPERSTRIP = 278,//!< For TIFF, use to specify the number of rows per strip.
110 IMWRITE_TIFF_PREDICTOR = 317,//!< For TIFF, use to specify predictor. See cv::ImwriteTiffPredictorFlags.
111 IMWRITE_JPEG2000_COMPRESSION_X1000 = 272,//!< For JPEG2000, use to specify the target compression rate (multiplied by 1000). The value can be from 0 to 1000. Default is 1000.
112 IMWRITE_AVIF_QUALITY = 512,//!< For AVIF, it can be a quality between 0 and 100 (the higher the better). Default is 95.
113 IMWRITE_AVIF_DEPTH = 513,//!< For AVIF, it can be 8, 10 or 12. If >8, it is stored/read as CV_32F. Default is 8.
114 IMWRITE_AVIF_SPEED = 514,//!< For AVIF, it is between 0 (slowest) and (fastest). Default is 9.
115 IMWRITE_JPEGXL_QUALITY = 640,//!< For JPEG XL, it can be a quality from 0 to 100 (the higher is the better). Default value is 95. If set, distance parameter is re-calicurated from quality level automatically. This parameter request libjxl v0.10 or later.
116 IMWRITE_JPEGXL_EFFORT = 641,//!< For JPEG XL, encoder effort/speed level without affecting decoding speed; it is between 1 (fastest) and 10 (slowest). Default is 7.
117 IMWRITE_JPEGXL_DISTANCE = 642,//!< For JPEG XL, distance level for lossy compression: target max butteraugli distance, lower = higher quality, 0 = lossless; range: 0 .. 25. Default is 1.
118 IMWRITE_JPEGXL_DECODING_SPEED = 643,//!< For JPEG XL, decoding speed tier for the provided options; minimum is 0 (slowest to decode, best quality/density), and maximum is 4 (fastest to decode, at the cost of some quality/density). Default is 0.
119 IMWRITE_GIF_LOOP = 1024,//!< For GIF, it can be a loop flag from 0 to 65535. Default is 0 - loop forever.
120 IMWRITE_GIF_SPEED = 1025,//!< For GIF, it is between 1 (slowest) and 100 (fastest). Default is 96.
121 IMWRITE_GIF_QUALITY = 1026, //!< For GIF, it can be a quality from 1 to 8. Default is 2. See cv::ImwriteGifCompressionFlags.
122 IMWRITE_GIF_DITHER = 1027, //!< For GIF, it can be a quality from -1(most dither) to 3(no dither). Default is 0.
123 IMWRITE_GIF_TRANSPARENCY = 1028, //!< For GIF, the alpha channel lower than this will be set to transparent. Default is 1.
124 IMWRITE_GIF_COLORTABLE = 1029 //!< For GIF, 0 means global color table is used, 1 means local color table is used. Default is 0.
125};
126
127enum ImwriteJPEGSamplingFactorParams {
128 IMWRITE_JPEG_SAMPLING_FACTOR_411 = 0x411111, //!< 4x1,1x1,1x1
129 IMWRITE_JPEG_SAMPLING_FACTOR_420 = 0x221111, //!< 2x2,1x1,1x1(Default)
130 IMWRITE_JPEG_SAMPLING_FACTOR_422 = 0x211111, //!< 2x1,1x1,1x1
131 IMWRITE_JPEG_SAMPLING_FACTOR_440 = 0x121111, //!< 1x2,1x1,1x1
132 IMWRITE_JPEG_SAMPLING_FACTOR_444 = 0x111111 //!< 1x1,1x1,1x1(No subsampling)
133 };
134
135enum ImwriteTiffCompressionFlags {
136 IMWRITE_TIFF_COMPRESSION_NONE = 1, //!< dump mode
137 IMWRITE_TIFF_COMPRESSION_CCITTRLE = 2, //!< CCITT modified Huffman RLE
138 IMWRITE_TIFF_COMPRESSION_CCITTFAX3 = 3, //!< CCITT Group 3 fax encoding
139 IMWRITE_TIFF_COMPRESSION_CCITT_T4 = 3, //!< CCITT T.4 (TIFF 6 name)
140 IMWRITE_TIFF_COMPRESSION_CCITTFAX4 = 4, //!< CCITT Group 4 fax encoding
141 IMWRITE_TIFF_COMPRESSION_CCITT_T6 = 4, //!< CCITT T.6 (TIFF 6 name)
142 IMWRITE_TIFF_COMPRESSION_LZW = 5, //!< Lempel-Ziv & Welch
143 IMWRITE_TIFF_COMPRESSION_OJPEG = 6, //!< !6.0 JPEG
144 IMWRITE_TIFF_COMPRESSION_JPEG = 7, //!< %JPEG DCT compression
145 IMWRITE_TIFF_COMPRESSION_T85 = 9, //!< !TIFF/FX T.85 JBIG compression
146 IMWRITE_TIFF_COMPRESSION_T43 = 10, //!< !TIFF/FX T.43 colour by layered JBIG compression
147 IMWRITE_TIFF_COMPRESSION_NEXT = 32766, //!< NeXT 2-bit RLE
148 IMWRITE_TIFF_COMPRESSION_CCITTRLEW = 32771, //!< #1 w/ word alignment
149 IMWRITE_TIFF_COMPRESSION_PACKBITS = 32773, //!< Macintosh RLE
150 IMWRITE_TIFF_COMPRESSION_THUNDERSCAN = 32809, //!< ThunderScan RLE
151 IMWRITE_TIFF_COMPRESSION_IT8CTPAD = 32895, //!< IT8 CT w/padding
152 IMWRITE_TIFF_COMPRESSION_IT8LW = 32896, //!< IT8 Linework RLE
153 IMWRITE_TIFF_COMPRESSION_IT8MP = 32897, //!< IT8 Monochrome picture
154 IMWRITE_TIFF_COMPRESSION_IT8BL = 32898, //!< IT8 Binary line art
155 IMWRITE_TIFF_COMPRESSION_PIXARFILM = 32908, //!< Pixar companded 10bit LZW
156 IMWRITE_TIFF_COMPRESSION_PIXARLOG = 32909, //!< Pixar companded 11bit ZIP
157 IMWRITE_TIFF_COMPRESSION_DEFLATE = 32946, //!< Deflate compression, legacy tag
158 IMWRITE_TIFF_COMPRESSION_ADOBE_DEFLATE = 8, //!< Deflate compression, as recognized by Adobe
159 IMWRITE_TIFF_COMPRESSION_DCS = 32947, //!< Kodak DCS encoding
160 IMWRITE_TIFF_COMPRESSION_JBIG = 34661, //!< ISO JBIG
161 IMWRITE_TIFF_COMPRESSION_SGILOG = 34676, //!< SGI Log Luminance RLE
162 IMWRITE_TIFF_COMPRESSION_SGILOG24 = 34677, //!< SGI Log 24-bit packed
163 IMWRITE_TIFF_COMPRESSION_JP2000 = 34712, //!< Leadtools JPEG2000
164 IMWRITE_TIFF_COMPRESSION_LERC = 34887, //!< ESRI Lerc codec: https://github.com/Esri/lerc
165 IMWRITE_TIFF_COMPRESSION_LZMA = 34925, //!< LZMA2
166 IMWRITE_TIFF_COMPRESSION_ZSTD = 50000, //!< ZSTD: WARNING not registered in Adobe-maintained registry
167 IMWRITE_TIFF_COMPRESSION_WEBP = 50001, //!< WEBP: WARNING not registered in Adobe-maintained registry
168 IMWRITE_TIFF_COMPRESSION_JXL = 50002 //!< JPEGXL: WARNING not registered in Adobe-maintained registry
169};
170
171enum ImwriteTiffPredictorFlags {
172 IMWRITE_TIFF_PREDICTOR_NONE = 1, //!< no prediction scheme used
173 IMWRITE_TIFF_PREDICTOR_HORIZONTAL = 2, //!< horizontal differencing
174 IMWRITE_TIFF_PREDICTOR_FLOATINGPOINT = 3 //!< floating point predictor
175
176};
177
178enum ImwriteEXRTypeFlags {
179 /*IMWRITE_EXR_TYPE_UNIT = 0, //!< not supported */
180 IMWRITE_EXR_TYPE_HALF = 1, //!< store as HALF (FP16)
181 IMWRITE_EXR_TYPE_FLOAT = 2 //!< store as FP32 (default)
182 };
183
184enum ImwriteEXRCompressionFlags {
185 IMWRITE_EXR_COMPRESSION_NO = 0, //!< no compression
186 IMWRITE_EXR_COMPRESSION_RLE = 1, //!< run length encoding
187 IMWRITE_EXR_COMPRESSION_ZIPS = 2, //!< zlib compression, one scan line at a time
188 IMWRITE_EXR_COMPRESSION_ZIP = 3, //!< zlib compression, in blocks of 16 scan lines
189 IMWRITE_EXR_COMPRESSION_PIZ = 4, //!< piz-based wavelet compression
190 IMWRITE_EXR_COMPRESSION_PXR24 = 5, //!< lossy 24-bit float compression
191 IMWRITE_EXR_COMPRESSION_B44 = 6, //!< lossy 4-by-4 pixel block compression, fixed compression rate
192 IMWRITE_EXR_COMPRESSION_B44A = 7, //!< lossy 4-by-4 pixel block compression, flat fields are compressed more
193 IMWRITE_EXR_COMPRESSION_DWAA = 8, //!< lossy DCT based compression, in blocks of 32 scanlines. More efficient for partial buffer access. Supported since OpenEXR 2.2.0.
194 IMWRITE_EXR_COMPRESSION_DWAB = 9, //!< 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.
195 };
196
197//! Imwrite PNG specific flags used to tune the compression algorithm.
198/** These flags will be modify the way of PNG image compression and will be passed to the underlying zlib processing stage.
199
200- 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.
201- 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.
202- The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately.
203- IMWRITE_PNG_STRATEGY_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.
204*/
205enum ImwritePNGFlags {
206 IMWRITE_PNG_STRATEGY_DEFAULT = 0, //!< Use this value for normal data.
207 IMWRITE_PNG_STRATEGY_FILTERED = 1, //!< 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.
208 IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY = 2, //!< Use this value to force Huffman encoding only (no string match).
209 IMWRITE_PNG_STRATEGY_RLE = 3, //!< Use this value to limit match distances to one (run-length encoding).
210 IMWRITE_PNG_STRATEGY_FIXED = 4 //!< Using this value prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.
211 };
212
213//! Imwrite PAM specific tupletype flags used to define the 'TUPLETYPE' field of a PAM file.
214enum ImwritePAMFlags {
215 IMWRITE_PAM_FORMAT_NULL = 0,
216 IMWRITE_PAM_FORMAT_BLACKANDWHITE = 1,
217 IMWRITE_PAM_FORMAT_GRAYSCALE = 2,
218 IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA = 3,
219 IMWRITE_PAM_FORMAT_RGB = 4,
220 IMWRITE_PAM_FORMAT_RGB_ALPHA = 5
221 };
222
223//! Imwrite HDR specific values for IMWRITE_HDR_COMPRESSION parameter key
224enum ImwriteHDRCompressionFlags {
225 IMWRITE_HDR_COMPRESSION_NONE = 0,
226 IMWRITE_HDR_COMPRESSION_RLE = 1
227};
228
229//! Imwrite GIF specific values for IMWRITE_GIF_QUALITY parameter key, if larger than 3, then its related to the size of the color table.
230enum ImwriteGIFCompressionFlags {
231 IMWRITE_GIF_FAST_NO_DITHER = 1,
232 IMWRITE_GIF_FAST_FLOYD_DITHER = 2,
233 IMWRITE_GIF_COLORTABLE_SIZE_8 = 3,
234 IMWRITE_GIF_COLORTABLE_SIZE_16 = 4,
235 IMWRITE_GIF_COLORTABLE_SIZE_32 = 5,
236 IMWRITE_GIF_COLORTABLE_SIZE_64 = 6,
237 IMWRITE_GIF_COLORTABLE_SIZE_128 = 7,
238 IMWRITE_GIF_COLORTABLE_SIZE_256 = 8
239};
240
241//! @} imgcodecs_flags
242
243/** @brief Represents an animation with multiple frames.
244The `Animation` struct is designed to store and manage data for animated sequences such as those from animated formats (e.g., GIF, AVIF, APNG, WebP).
245It provides support for looping, background color settings, frame timing, and frame storage.
246*/
247struct CV_EXPORTS_W_SIMPLE Animation
248{
249 //! Number of times the animation should loop. 0 means infinite looping.
250 CV_PROP_RW int loop_count;
251 //! Background color of the animation in BGRA format.
252 CV_PROP_RW Scalar bgcolor;
253 //! Duration for each frame in milliseconds.
254 CV_PROP_RW std::vector<int> durations;
255 //! Vector of frames, where each Mat represents a single frame.
256 CV_PROP_RW std::vector<Mat> frames;
257
258 /** @brief Constructs an Animation object with optional loop count and background color.
259
260 @param loopCount An integer representing the number of times the animation should loop:
261 - `0` (default) indicates infinite looping, meaning the animation will replay continuously.
262 - Positive values denote finite repeat counts, allowing the animation to play a limited number of times.
263 - If a negative value or a value beyond the maximum of `0xffff` (65535) is provided, it is reset to `0`
264 (infinite looping) to maintain valid bounds.
265
266 @param bgColor A `Scalar` object representing the background color in BGRA format:
267 - Defaults to `Scalar()`, indicating an empty color (usually transparent if supported).
268 - This background color provides a solid fill behind frames that have transparency, ensuring a consistent display appearance.
269 */
270 Animation(int loopCount = 0, Scalar bgColor = Scalar());
271};
272
273/** @brief Loads an image from a file.
274
275@anchor imread
276
277The `imread` function loads an image from the specified file and returns OpenCV matrix. If the image cannot be
278read (because of a missing file, improper permissions, or unsupported/invalid format), the function
279returns an empty matrix.
280
281Currently, the following file formats are supported:
282
283- Windows bitmaps - \*.bmp, \*.dib (always supported)
284- GIF files - \*.gif (always supported)
285- JPEG files - \*.jpeg, \*.jpg, \*.jpe (see the *Note* section)
286- JPEG 2000 files - \*.jp2 (see the *Note* section)
287- Portable Network Graphics - \*.png (see the *Note* section)
288- WebP - \*.webp (see the *Note* section)
289- AVIF - \*.avif (see the *Note* section)
290- Portable image format - \*.pbm, \*.pgm, \*.ppm, \*.pxm, \*.pnm (always supported)
291- PFM files - \*.pfm (see the *Note* section)
292- Sun rasters - \*.sr, \*.ras (always supported)
293- TIFF files - \*.tiff, \*.tif (see the *Note* section)
294- OpenEXR Image files - \*.exr (see the *Note* section)
295- Radiance HDR - \*.hdr, \*.pic (always supported)
296- Raster and Vector geospatial data supported by GDAL (see the *Note* section)
297
298@note
299- The function determines the type of an image by its content, not by the file extension.
300- In the case of color images, the decoded images will have the channels stored in **B G R** order.
301- When using IMREAD_GRAYSCALE, the codec's internal grayscale conversion will be used, if available.
302 Results may differ from the output of cvtColor().
303- On Microsoft Windows\* and Mac OS\*, the codecs shipped with OpenCV (libjpeg, libpng, libtiff,
304 and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs, and TIFFs. On Mac OS,
305 there is also an option to use native Mac OS image readers. However, beware that currently these
306 native image loaders give images with different pixel values because of the color management embedded
307 into Mac OS.
308- On Linux\*, BSD flavors, and other Unix-like open-source operating systems, OpenCV looks for
309 codecs supplied with the OS. Ensure the relevant packages are installed (including development
310 files, such as "libjpeg-dev" in Debian\* and Ubuntu\*) to get codec support, or turn
311 on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
312- If the *WITH_GDAL* flag is set to true in CMake and @ref IMREAD_LOAD_GDAL is used to load the image,
313 the [GDAL](http://www.gdal.org) driver will be used to decode the image, supporting
314 [Raster](http://www.gdal.org/formats_list.html) and [Vector](http://www.gdal.org/ogr_formats.html) formats.
315- If EXIF information is embedded in the image file, the EXIF orientation will be taken into account,
316 and thus the image will be rotated accordingly unless the flags @ref IMREAD_IGNORE_ORIENTATION
317 or @ref IMREAD_UNCHANGED are passed.
318- Use the IMREAD_UNCHANGED flag to preserve the floating-point values from PFM images.
319- By default, the number of pixels must be less than 2^30. This limit can be changed by setting
320 the environment variable `OPENCV_IO_MAX_IMAGE_PIXELS`. See @ref tutorial_env_reference.
321
322@param filename Name of the file to be loaded.
323@param flags Flag that can take values of `cv::ImreadModes`.
324*/
325CV_EXPORTS_W Mat imread( const String& filename, int flags = IMREAD_COLOR_BGR );
326
327/** @brief Loads an image from a file.
328
329This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts and the return value.
330@param filename Name of file to be loaded.
331@param dst object in which the image will be loaded.
332@param flags Flag that can take values of cv::ImreadModes
333@note
334The image passing through the img parameter can be pre-allocated. The memory is reused if the shape and the type match with the load image.
335 */
336CV_EXPORTS_W void imread( const String& filename, OutputArray dst, int flags = IMREAD_COLOR_BGR );
337
338/** @brief Loads a multi-page image from a file.
339
340The function imreadmulti loads a multi-page image from the specified file into a vector of Mat objects.
341@param filename Name of file to be loaded.
342@param mats A vector of Mat objects holding each page.
343@param flags Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR.
344@sa cv::imread
345*/
346CV_EXPORTS_W bool imreadmulti(const String& filename, CV_OUT std::vector<Mat>& mats, int flags = IMREAD_ANYCOLOR);
347
348/** @brief Loads images of a multi-page image from a file.
349
350The function imreadmulti loads a specified range from a multi-page image from the specified file into a vector of Mat objects.
351@param filename Name of file to be loaded.
352@param mats A vector of Mat objects holding each page.
353@param start Start index of the image to load
354@param count Count number of images to load
355@param flags Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR.
356@sa cv::imread
357*/
358CV_EXPORTS_W bool imreadmulti(const String& filename, CV_OUT std::vector<Mat>& mats, int start, int count, int flags = IMREAD_ANYCOLOR);
359
360/** @example samples/cpp/tutorial_code/imgcodecs/animations.cpp
361An example to show usage of cv::imreadanimation and cv::imwriteanimation functions.
362Check @ref tutorial_animations "the corresponding tutorial" for more details
363*/
364
365/** @brief Loads frames from an animated image file into an Animation structure.
366
367The function imreadanimation loads frames from an animated image file (e.g., GIF, AVIF, APNG, WEBP) into the provided Animation struct.
368
369@param filename A string containing the path to the file.
370@param animation A reference to an Animation structure where the loaded frames will be stored. It should be initialized before the function is called.
371@param start The index of the first frame to load. This is optional and defaults to 0.
372@param count The number of frames to load. This is optional and defaults to 32767.
373
374@return Returns true if the file was successfully loaded and frames were extracted; returns false otherwise.
375*/
376CV_EXPORTS_W bool imreadanimation(const String& filename, CV_OUT Animation& animation, int start = 0, int count = INT16_MAX);
377
378/** @brief Saves an Animation to a specified file.
379
380The function imwriteanimation saves the provided Animation data to the specified file in an animated format.
381Supported formats depend on the implementation and may include formats like GIF, AVIF, APNG, or WEBP.
382
383@param filename The name of the file where the animation will be saved. The file extension determines the format.
384@param animation A constant reference to an Animation struct containing the frames and metadata to be saved.
385@param params Optional format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ...).
386These parameters are used to specify additional options for the encoding process. Refer to `cv::ImwriteFlags` for details on possible parameters.
387
388@return Returns true if the animation was successfully saved; returns false otherwise.
389*/
390CV_EXPORTS_W bool imwriteanimation(const String& filename, const Animation& animation, const std::vector<int>& params = std::vector<int>());
391
392/** @brief Returns the number of images inside the given file
393
394The function imcount returns the number of pages in a multi-page image (e.g. TIFF), the number of frames in an animation (e.g. AVIF), and 1 otherwise.
395If the image cannot be decoded, 0 is returned.
396@param filename Name of file to be loaded.
397@param flags Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR.
398@todo when cv::IMREAD_LOAD_GDAL flag used the return value will be 0 or 1 because OpenCV's GDAL decoder doesn't support multi-page reading yet.
399*/
400CV_EXPORTS_W size_t imcount(const String& filename, int flags = IMREAD_ANYCOLOR);
401
402/** @brief Saves an image to a specified file.
403
404The function imwrite saves the image to the specified file. The image format is chosen based on the
405filename extension (see cv::imread for the list of extensions). In general, only 8-bit unsigned (CV_8U)
406single-channel or 3-channel (with 'BGR' channel order) images
407can be saved using this function, with these exceptions:
408
409- With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
410 - 8-bit unsigned (CV_8U) images are not supported.
411- With Radiance HDR encoder, non 64-bit float (CV_64F) images can be saved.
412 - All images will be converted to 32-bit float (CV_32F).
413- With JPEG 2000 encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
414- With JPEG XL encoder, 8-bit unsigned (CV_8U), 16-bit unsigned (CV_16U) and 32-bit float(CV_32F) images can be saved.
415 - JPEG XL images with an alpha channel can be saved using this function.
416 To do this, create 8-bit (or 16-bit, 32-bit float) 4-channel image BGRA, where the alpha channel goes last.
417 Fully transparent pixels should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535/1.0.
418- With PAM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
419- With PNG encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
420 - PNG images with an alpha channel can be saved using this function. To do this, create
421 8-bit (or 16-bit) 4-channel image BGRA, where the alpha channel goes last. Fully transparent pixels
422 should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535 (see the code sample below).
423- With PGM/PPM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
424- With TIFF encoder, 8-bit unsigned (CV_8U), 8-bit signed (CV_8S),
425 16-bit unsigned (CV_16U), 16-bit signed (CV_16S),
426 32-bit signed (CV_32S),
427 32-bit float (CV_32F) and 64-bit float (CV_64F) images can be saved.
428 - Multiple images (vector of Mat) can be saved in TIFF format (see the code sample below).
429 - 32-bit float 3-channel (CV_32FC3) TIFF images will be saved
430 using the LogLuv high dynamic range encoding (4 bytes per pixel)
431
432If the image format is not supported, the image will be converted to 8-bit unsigned (CV_8U) and saved that way.
433
434If the format, depth or channel order is different, use
435Mat::convertTo and cv::cvtColor to convert it before saving. Or, use the universal FileStorage I/O
436functions to save the image to XML or YAML format.
437
438The sample below shows how to create a BGRA image, how to set custom compression parameters and save it to a PNG file.
439It also demonstrates how to save multiple images in a TIFF file:
440@include snippets/imgcodecs_imwrite.cpp
441@param filename Name of the file.
442@param img (Mat or vector of Mat) Image or Images to be saved.
443@param params Format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ... .) see cv::ImwriteFlags
444*/
445CV_EXPORTS_W bool imwrite( const String& filename, InputArray img,
446 const std::vector<int>& params = std::vector<int>());
447
448//! @brief multi-image overload for bindings
449CV_WRAP static inline
450bool imwritemulti(const String& filename, InputArrayOfArrays img,
451 const std::vector<int>& params = std::vector<int>())
452{
453 return imwrite(filename, img, params);
454}
455
456/** @brief Reads an image from a buffer in memory.
457
458The function imdecode reads an image from the specified buffer in the memory. If the buffer is too short or
459contains invalid data, the function returns an empty matrix ( Mat::data==NULL ).
460
461See cv::imread for the list of supported formats and flags description.
462
463@note In the case of color images, the decoded images will have the channels stored in **B G R** order.
464@param buf Input array or vector of bytes.
465@param flags The same flags as in cv::imread, see cv::ImreadModes.
466*/
467CV_EXPORTS_W Mat imdecode( InputArray buf, int flags );
468
469/** @overload
470@param buf Input array or vector of bytes.
471@param flags The same flags as in cv::imread, see cv::ImreadModes.
472@param dst The optional output placeholder for the decoded matrix. It can save the image
473reallocations when the function is called repeatedly for images of the same size. In case of decoder
474failure the function returns empty cv::Mat object, but does not release user-provided dst buffer.
475*/
476CV_EXPORTS Mat imdecode( InputArray buf, int flags, Mat* dst);
477
478/** @brief Reads a multi-page image from a buffer in memory.
479
480The function imdecodemulti reads a multi-page image from the specified buffer in the memory. If the buffer is too short or
481contains invalid data, the function returns false.
482
483See cv::imreadmulti for the list of supported formats and flags description.
484
485@note In the case of color images, the decoded images will have the channels stored in **B G R** order.
486@param buf Input array or vector of bytes.
487@param flags The same flags as in cv::imread, see cv::ImreadModes.
488@param mats A vector of Mat objects holding each page, if more than one.
489@param range A continuous selection of pages.
490*/
491CV_EXPORTS_W bool imdecodemulti(InputArray buf, int flags, CV_OUT std::vector<Mat>& mats, const cv::Range& range = Range::all());
492
493/** @brief Encodes an image into a memory buffer.
494
495The function imencode compresses the image and stores it in the memory buffer that is resized to fit the
496result. See cv::imwrite for the list of supported formats and flags description.
497
498@param ext File extension that defines the output format. Must include a leading period.
499@param img Image to be compressed.
500@param buf Output buffer resized to fit the compressed image.
501@param params Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.
502*/
503CV_EXPORTS_W bool imencode( const String& ext, InputArray img,
504 CV_OUT std::vector<uchar>& buf,
505 const std::vector<int>& params = std::vector<int>());
506
507/** @brief Encodes array of images into a memory buffer.
508
509The function is analog to cv::imencode for in-memory multi-page image compression.
510See cv::imwrite for the list of supported formats and flags description.
511
512@param ext File extension that defines the output format. Must include a leading period.
513@param imgs Vector of images to be written.
514@param buf Output buffer resized to fit the compressed data.
515@param params Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.
516*/
517CV_EXPORTS_W bool imencodemulti( const String& ext, InputArrayOfArrays imgs,
518 CV_OUT std::vector<uchar>& buf,
519 const std::vector<int>& params = std::vector<int>());
520
521/** @brief Checks if the specified image file can be decoded by OpenCV.
522
523The function haveImageReader checks if OpenCV is capable of reading the specified file.
524This can be useful for verifying support for a given image format before attempting to load an image.
525
526@param filename The name of the file to be checked.
527@return true if an image reader for the specified file is available and the file can be opened, false otherwise.
528
529@note The function checks the availability of image codecs that are either built into OpenCV or dynamically loaded.
530It does not check for the actual existence of the file but rather the ability to read the specified file type.
531If the file cannot be opened or the format is unsupported, the function will return false.
532
533@sa cv::haveImageWriter, cv::imread, cv::imdecode
534*/
535CV_EXPORTS_W bool haveImageReader( const String& filename );
536
537/** @brief Checks if the specified image file or specified file extension can be encoded by OpenCV.
538
539The function haveImageWriter checks if OpenCV is capable of writing images with the specified file extension.
540This can be useful for verifying support for a given image format before attempting to save an image.
541
542@param filename The name of the file or the file extension (e.g., ".jpg", ".png").
543It is recommended to provide the file extension rather than the full file name.
544@return true if an image writer for the specified extension is available, false otherwise.
545
546@note The function checks the availability of image codecs that are either built into OpenCV or dynamically loaded.
547It does not check for the actual existence of the file but rather the ability to write files of the given type.
548
549@sa cv::haveImageReader, cv::imwrite, cv::imencode
550*/
551CV_EXPORTS_W bool haveImageWriter( const String& filename );
552
553/** @brief To read multi-page images on demand
554
555The ImageCollection class provides iterator API to read multi-page images on demand. Create iterator
556to the collection of the images and iterate over the collection. Decode the necessary page with operator*.
557
558The performance of page decoding is O(1) if collection is increment sequentially. If the user wants to access random page,
559then the time Complexity is O(n) because the collection has to be reinitialized every time in order to go to the correct page.
560However, the intermediate pages are not decoded during the process, so typically it's quite fast.
561This is required because multi-page codecs does not support going backwards.
562After decoding the one page, it is stored inside the collection cache. Hence, trying to get Mat object from already decoded page is O(1).
563If you need memory, you can use .releaseCache() method to release cached index.
564The space complexity is O(n) if all pages are decoded into memory. The user is able to decode and release images on demand.
565*/
566class CV_EXPORTS ImageCollection {
567public:
568 struct CV_EXPORTS iterator {
569 iterator(ImageCollection* col);
570 iterator(ImageCollection* col, int end);
571 Mat& operator*();
572 Mat* operator->();
573 iterator& operator++();
574 iterator operator++(int);
575 friend bool operator== (const iterator& a, const iterator& b) { return a.m_curr == b.m_curr; }
576 friend bool operator!= (const iterator& a, const iterator& b) { return a.m_curr != b.m_curr; }
577
578 private:
579 ImageCollection* m_pCollection;
580 int m_curr;
581 };
582
583 ImageCollection();
584 ImageCollection(const String& filename, int flags);
585 void init(const String& img, int flags);
586 size_t size() const;
587 const Mat& at(int index);
588 const Mat& operator[](int index);
589 void releaseCache(int index);
590 iterator begin();
591 iterator end();
592
593 class Impl;
594 Ptr<Impl> getImpl();
595protected:
596 Ptr<Impl> pImpl;
597};
598
599//! @} imgcodecs
600
601} // cv
602
603#endif //OPENCV_IMGCODECS_HPP
604

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source code of opencv/modules/imgcodecs/include/opencv2/imgcodecs.hpp