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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_c C API
52     @defgroup imgcodecs_ios iOS glue
53   @}
54 */
55 
56 //////////////////////////////// image codec ////////////////////////////////
57 namespace cv
58 {
59 
60 //! @addtogroup imgcodecs
61 //! @{
62 
63 //! Imread flags
64 enum ImreadModes {
65        IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped).
66        IMREAD_GRAYSCALE            = 0,  //!< If set, always convert image to the single channel grayscale image (codec internal conversion).
67        IMREAD_COLOR                = 1,  //!< If set, always convert image to the 3 channel BGR color image.
68        IMREAD_ANYDEPTH             = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
69        IMREAD_ANYCOLOR             = 4,  //!< If set, the image is read in any possible color format.
70        IMREAD_LOAD_GDAL            = 8,  //!< If set, use the gdal driver for loading the image.
71        IMREAD_REDUCED_GRAYSCALE_2  = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.
72        IMREAD_REDUCED_COLOR_2      = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.
73        IMREAD_REDUCED_GRAYSCALE_4  = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.
74        IMREAD_REDUCED_COLOR_4      = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.
75        IMREAD_REDUCED_GRAYSCALE_8  = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.
76        IMREAD_REDUCED_COLOR_8      = 65, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.
77        IMREAD_IGNORE_ORIENTATION   = 128 //!< If set, do not rotate the image according to EXIF's orientation flag.
78      };
79 
80 //! Imwrite flags
81 enum ImwriteFlags {
82        IMWRITE_JPEG_QUALITY        = 1,  //!< For JPEG, it can be a quality from 0 to 100 (the higher is the better). Default value is 95.
83        IMWRITE_JPEG_PROGRESSIVE    = 2,  //!< Enable JPEG features, 0 or 1, default is False.
84        IMWRITE_JPEG_OPTIMIZE       = 3,  //!< Enable JPEG features, 0 or 1, default is False.
85        IMWRITE_JPEG_RST_INTERVAL   = 4,  //!< JPEG restart interval, 0 - 65535, default is 0 - no restart.
86        IMWRITE_JPEG_LUMA_QUALITY   = 5,  //!< Separate luma quality level, 0 - 100, default is 0 - don't use.
87        IMWRITE_JPEG_CHROMA_QUALITY = 6,  //!< Separate chroma quality level, 0 - 100, default is 0 - don't use.
88        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).
89        IMWRITE_PNG_STRATEGY        = 17, //!< One of cv::ImwritePNGFlags, default is IMWRITE_PNG_STRATEGY_RLE.
90        IMWRITE_PNG_BILEVEL         = 18, //!< Binary level PNG, 0 or 1, default is 0.
91        IMWRITE_PXM_BINARY          = 32, //!< For PPM, PGM, or PBM, it can be a binary format flag, 0 or 1. Default value is 1.
92        IMWRITE_EXR_TYPE            = (3 << 4) + 0, /* 48 */ //!< override EXR storage type (FLOAT (FP32) is default)
93        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.
94        IMWRITE_PAM_TUPLETYPE       = 128,//!< For PAM, sets the TUPLETYPE field to the corresponding string value that is defined for the format
95        IMWRITE_TIFF_RESUNIT = 256,//!< For TIFF, use to specify which DPI resolution unit to set; see libtiff documentation for valid values
96        IMWRITE_TIFF_XDPI = 257,//!< For TIFF, use to specify the X direction DPI
97        IMWRITE_TIFF_YDPI = 258 //!< For TIFF, use to specify the Y direction DPI
98      };
99 
100 enum ImwriteEXRTypeFlags {
101        /*IMWRITE_EXR_TYPE_UNIT = 0, //!< not supported */
102        IMWRITE_EXR_TYPE_HALF = 1,   //!< store as HALF (FP16)
103        IMWRITE_EXR_TYPE_FLOAT = 2   //!< store as FP32 (default)
104      };
105 
106 //! Imwrite PNG specific flags used to tune the compression algorithm.
107 /** These flags will be modify the way of PNG image compression and will be passed to the underlying zlib processing stage.
108 
109 -   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.
110 -   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.
111 -   The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately.
112 -   IMWRITE_PNG_STRATEGY_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.
113 */
114 enum ImwritePNGFlags {
115        IMWRITE_PNG_STRATEGY_DEFAULT      = 0, //!< Use this value for normal data.
116        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.
117        IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY = 2, //!< Use this value to force Huffman encoding only (no string match).
118        IMWRITE_PNG_STRATEGY_RLE          = 3, //!< Use this value to limit match distances to one (run-length encoding).
119        IMWRITE_PNG_STRATEGY_FIXED        = 4  //!< Using this value prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.
120      };
121 
122 //! Imwrite PAM specific tupletype flags used to define the 'TUPETYPE' field of a PAM file.
123 enum ImwritePAMFlags {
124        IMWRITE_PAM_FORMAT_NULL = 0,
125        IMWRITE_PAM_FORMAT_BLACKANDWHITE = 1,
126        IMWRITE_PAM_FORMAT_GRAYSCALE = 2,
127        IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA = 3,
128        IMWRITE_PAM_FORMAT_RGB = 4,
129        IMWRITE_PAM_FORMAT_RGB_ALPHA = 5,
130      };
131 
132 /** @brief Loads an image from a file.
133 
134 @anchor imread
135 
136 The function imread loads an image from the specified file and returns it. If the image cannot be
137 read (because of missing file, improper permissions, unsupported or invalid format), the function
138 returns an empty matrix ( Mat::data==NULL ).
139 
140 Currently, the following file formats are supported:
141 
142 -   Windows bitmaps - \*.bmp, \*.dib (always supported)
143 -   JPEG files - \*.jpeg, \*.jpg, \*.jpe (see the *Note* section)
144 -   JPEG 2000 files - \*.jp2 (see the *Note* section)
145 -   Portable Network Graphics - \*.png (see the *Note* section)
146 -   WebP - \*.webp (see the *Note* section)
147 -   Portable image format - \*.pbm, \*.pgm, \*.ppm \*.pxm, \*.pnm (always supported)
148 -   Sun rasters - \*.sr, \*.ras (always supported)
149 -   TIFF files - \*.tiff, \*.tif (see the *Note* section)
150 -   OpenEXR Image files - \*.exr (see the *Note* section)
151 -   Radiance HDR - \*.hdr, \*.pic (always supported)
152 -   Raster and Vector geospatial data supported by GDAL (see the *Note* section)
153 
154 @note
155 -   The function determines the type of an image by the content, not by the file extension.
156 -   In the case of color images, the decoded images will have the channels stored in **B G R** order.
157 -   When using IMREAD_GRAYSCALE, the codec's internal grayscale conversion will be used, if available.
158     Results may differ to the output of cvtColor()
159 -   On Microsoft Windows\* OS and MacOSX\*, the codecs shipped with an OpenCV image (libjpeg,
160     libpng, libtiff, and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs,
161     and TIFFs. On MacOSX, there is also an option to use native MacOSX image readers. But beware
162     that currently these native image loaders give images with different pixel values because of
163     the color management embedded into MacOSX.
164 -   On Linux\*, BSD flavors and other Unix-like open-source operating systems, OpenCV looks for
165     codecs supplied with an OS image. Install the relevant packages (do not forget the development
166     files, for example, "libjpeg-dev", in Debian\* and Ubuntu\*) to get the codec support or turn
167     on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
168 -   In the case you set *WITH_GDAL* flag to true in CMake and @ref IMREAD_LOAD_GDAL to load the image,
169     then the [GDAL](http://www.gdal.org) driver will be used in order to decode the image, supporting
170     the following formats: [Raster](http://www.gdal.org/formats_list.html),
171     [Vector](http://www.gdal.org/ogr_formats.html).
172 -   If EXIF information are embedded in the image file, the EXIF orientation will be taken into account
173     and thus the image will be rotated accordingly except if the flag @ref IMREAD_IGNORE_ORIENTATION is passed.
174 -   By default number of pixels must be less than 2^30. Limit can be set using system
175     variable OPENCV_IO_MAX_IMAGE_PIXELS
176 
177 @param filename Name of file to be loaded.
178 @param flags Flag that can take values of cv::ImreadModes
179 */
180 CV_EXPORTS_W Mat imread( const String& filename, int flags = IMREAD_COLOR );
181 
182 /** @brief Loads a multi-page image from a file.
183 
184 The function imreadmulti loads a multi-page image from the specified file into a vector of Mat objects.
185 @param filename Name of file to be loaded.
186 @param flags Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR.
187 @param mats A vector of Mat objects holding each page, if more than one.
188 @sa cv::imread
189 */
190 CV_EXPORTS_W bool imreadmulti(const String& filename, CV_OUT std::vector<Mat>& mats, int flags = IMREAD_ANYCOLOR);
191 
192 /** @brief Saves an image to a specified file.
193 
194 The function imwrite saves the image to the specified file. The image format is chosen based on the
195 filename extension (see cv::imread for the list of extensions). In general, only 8-bit
196 single-channel or 3-channel (with 'BGR' channel order) images
197 can be saved using this function, with these exceptions:
198 
199 - 16-bit unsigned (CV_16U) images can be saved in the case of PNG, JPEG 2000, and TIFF formats
200 - 32-bit float (CV_32F) images can be saved in TIFF, OpenEXR, and Radiance HDR formats; 3-channel
201 (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
202 - PNG images with an alpha channel can be saved using this function. To do this, create
203 8-bit (or 16-bit) 4-channel image BGRA, where the alpha channel goes last. Fully transparent pixels
204 should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535 (see the code sample below).
205 
206 If the format, depth or channel order is different, use
207 Mat::convertTo and cv::cvtColor to convert it before saving. Or, use the universal FileStorage I/O
208 functions to save the image to XML or YAML format.
209 
210 The sample below shows how to create a BGRA image and save it to a PNG file. It also demonstrates how to set custom
211 compression parameters:
212 @include snippets/imgcodecs_imwrite.cpp
213 @param filename Name of the file.
214 @param img Image to be saved.
215 @param params Format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ... .) see cv::ImwriteFlags
216 */
217 CV_EXPORTS_W bool imwrite( const String& filename, InputArray img,
218               const std::vector<int>& params = std::vector<int>());
219 
220 /** @brief Reads an image from a buffer in memory.
221 
222 The function imdecode reads an image from the specified buffer in the memory. If the buffer is too short or
223 contains invalid data, the function returns an empty matrix ( Mat::data==NULL ).
224 
225 See cv::imread for the list of supported formats and flags description.
226 
227 @note In the case of color images, the decoded images will have the channels stored in **B G R** order.
228 @param buf Input array or vector of bytes.
229 @param flags The same flags as in cv::imread, see cv::ImreadModes.
230 */
231 CV_EXPORTS_W Mat imdecode( InputArray buf, int flags );
232 
233 /** @overload
234 @param buf
235 @param flags
236 @param dst The optional output placeholder for the decoded matrix. It can save the image
237 reallocations when the function is called repeatedly for images of the same size.
238 */
239 CV_EXPORTS Mat imdecode( InputArray buf, int flags, Mat* dst);
240 
241 /** @brief Encodes an image into a memory buffer.
242 
243 The function imencode compresses the image and stores it in the memory buffer that is resized to fit the
244 result. See cv::imwrite for the list of supported formats and flags description.
245 
246 @param ext File extension that defines the output format.
247 @param img Image to be written.
248 @param buf Output buffer resized to fit the compressed image.
249 @param params Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.
250 */
251 CV_EXPORTS_W bool imencode( const String& ext, InputArray img,
252                             CV_OUT std::vector<uchar>& buf,
253                             const std::vector<int>& params = std::vector<int>());
254 
255 //! @} imgcodecs
256 
257 } // cv
258 
259 #endif //OPENCV_IMGCODECS_HPP
260