Package org.opencv.imgcodecs

## Class Imgcodecs

- java.lang.Object
- - org.opencv.imgcodecs.Imgcodecs

-     public class Imgcodecs
      extends java.lang.Object

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `static int` | `IMREAD_ANYCOLOR` |
    `static int` | `IMREAD_ANYDEPTH` |
    `static int` | `IMREAD_COLOR` |
    `static int` | `IMREAD_GRAYSCALE` |
    `static int` | `IMREAD_IGNORE_ORIENTATION` |
    `static int` | `IMREAD_LOAD_GDAL` |
    `static int` | `IMREAD_REDUCED_COLOR_2` |
    `static int` | `IMREAD_REDUCED_COLOR_4` |
    `static int` | `IMREAD_REDUCED_COLOR_8` |
    `static int` | `IMREAD_REDUCED_GRAYSCALE_2` |
    `static int` | `IMREAD_REDUCED_GRAYSCALE_4` |
    `static int` | `IMREAD_REDUCED_GRAYSCALE_8` |
    `static int` | `IMREAD_UNCHANGED` |
    `static int` | `IMWRITE_EXR_TYPE` |
    `static int` | `IMWRITE_EXR_TYPE_FLOAT` |
    `static int` | `IMWRITE_EXR_TYPE_HALF` |
    `static int` | `IMWRITE_JPEG_CHROMA_QUALITY` |
    `static int` | `IMWRITE_JPEG_LUMA_QUALITY` |
    `static int` | `IMWRITE_JPEG_OPTIMIZE` |
    `static int` | `IMWRITE_JPEG_PROGRESSIVE` |
    `static int` | `IMWRITE_JPEG_QUALITY` |
    `static int` | `IMWRITE_JPEG_RST_INTERVAL` |
    `static int` | `IMWRITE_JPEG2000_COMPRESSION_X1000` |
    `static int` | `IMWRITE_PAM_FORMAT_BLACKANDWHITE` |
    `static int` | `IMWRITE_PAM_FORMAT_GRAYSCALE` |
    `static int` | `IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA` |
    `static int` | `IMWRITE_PAM_FORMAT_NULL` |
    `static int` | `IMWRITE_PAM_FORMAT_RGB` |
    `static int` | `IMWRITE_PAM_FORMAT_RGB_ALPHA` |
    `static int` | `IMWRITE_PAM_TUPLETYPE` |
    `static int` | `IMWRITE_PNG_BILEVEL` |
    `static int` | `IMWRITE_PNG_COMPRESSION` |
    `static int` | `IMWRITE_PNG_STRATEGY` |
    `static int` | `IMWRITE_PNG_STRATEGY_DEFAULT` |
    `static int` | `IMWRITE_PNG_STRATEGY_FILTERED` |
    `static int` | `IMWRITE_PNG_STRATEGY_FIXED` |
    `static int` | `IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY` |
    `static int` | `IMWRITE_PNG_STRATEGY_RLE` |
    `static int` | `IMWRITE_PXM_BINARY` |
    `static int` | `IMWRITE_TIFF_COMPRESSION` |
    `static int` | `IMWRITE_TIFF_RESUNIT` |
    `static int` | `IMWRITE_TIFF_XDPI` |
    `static int` | `IMWRITE_TIFF_YDPI` |
    `static int` | `IMWRITE_WEBP_QUALITY` |

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `Imgcodecs()` |

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `static boolean` | `haveImageReader​(java.lang.String filename)` | Returns true if the specified image can be decoded by OpenCV
    `static boolean` | `haveImageWriter​(java.lang.String filename)` | Returns true if an image with the specified filename can be encoded by OpenCV
    `static Mat` | `imdecode​(Mat buf, int flags)` | Reads an image from a buffer in memory.
    `static boolean` | `imencode​(java.lang.String ext, Mat img, MatOfByte buf)` | Encodes an image into a memory buffer.
    `static boolean` | `imencode​(java.lang.String ext, Mat img, MatOfByte buf, MatOfInt params)` | Encodes an image into a memory buffer.
    `static Mat` | `imread​(java.lang.String filename)` | Loads an image from a file.
    `static Mat` | `imread​(java.lang.String filename, int flags)` | Loads an image from a file.
    `static boolean` | `imreadmulti​(java.lang.String filename, java.util.List<Mat> mats)` | Loads a multi-page image from a file.
    `static boolean` | `imreadmulti​(java.lang.String filename, java.util.List<Mat> mats, int flags)` | Loads a multi-page image from a file.
    `static boolean` | `imwrite​(java.lang.String filename, Mat img)` | Saves an image to a specified file.
    `static boolean` | `imwrite​(java.lang.String filename, Mat img, MatOfInt params)` | Saves an image to a specified file.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### IMWRITE_PAM_FORMAT_NULL

          public static final int IMWRITE_PAM_FORMAT_NULL

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_FORMAT_BLACKANDWHITE

          public static final int IMWRITE_PAM_FORMAT_BLACKANDWHITE

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_FORMAT_GRAYSCALE

          public static final int IMWRITE_PAM_FORMAT_GRAYSCALE

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA

          public static final int IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_FORMAT_RGB

          public static final int IMWRITE_PAM_FORMAT_RGB

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_FORMAT_RGB_ALPHA

          public static final int IMWRITE_PAM_FORMAT_RGB_ALPHA

      See Also:
        Constant Field Values

    - #### IMREAD_UNCHANGED

          public static final int IMREAD_UNCHANGED

      See Also:
        Constant Field Values

    - #### IMREAD_GRAYSCALE

          public static final int IMREAD_GRAYSCALE

      See Also:
        Constant Field Values

    - #### IMREAD_COLOR

          public static final int IMREAD_COLOR

      See Also:
        Constant Field Values

    - #### IMREAD_ANYDEPTH

          public static final int IMREAD_ANYDEPTH

      See Also:
        Constant Field Values

    - #### IMREAD_ANYCOLOR

          public static final int IMREAD_ANYCOLOR

      See Also:
        Constant Field Values

    - #### IMREAD_LOAD_GDAL

          public static final int IMREAD_LOAD_GDAL

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_GRAYSCALE_2

          public static final int IMREAD_REDUCED_GRAYSCALE_2

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_COLOR_2

          public static final int IMREAD_REDUCED_COLOR_2

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_GRAYSCALE_4

          public static final int IMREAD_REDUCED_GRAYSCALE_4

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_COLOR_4

          public static final int IMREAD_REDUCED_COLOR_4

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_GRAYSCALE_8

          public static final int IMREAD_REDUCED_GRAYSCALE_8

      See Also:
        Constant Field Values

    - #### IMREAD_REDUCED_COLOR_8

          public static final int IMREAD_REDUCED_COLOR_8

      See Also:
        Constant Field Values

    - #### IMREAD_IGNORE_ORIENTATION

          public static final int IMREAD_IGNORE_ORIENTATION

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_QUALITY

          public static final int IMWRITE_JPEG_QUALITY

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_PROGRESSIVE

          public static final int IMWRITE_JPEG_PROGRESSIVE

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_OPTIMIZE

          public static final int IMWRITE_JPEG_OPTIMIZE

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_RST_INTERVAL

          public static final int IMWRITE_JPEG_RST_INTERVAL

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_LUMA_QUALITY

          public static final int IMWRITE_JPEG_LUMA_QUALITY

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG_CHROMA_QUALITY

          public static final int IMWRITE_JPEG_CHROMA_QUALITY

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_COMPRESSION

          public static final int IMWRITE_PNG_COMPRESSION

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY

          public static final int IMWRITE_PNG_STRATEGY

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_BILEVEL

          public static final int IMWRITE_PNG_BILEVEL

      See Also:
        Constant Field Values

    - #### IMWRITE_PXM_BINARY

          public static final int IMWRITE_PXM_BINARY

      See Also:
        Constant Field Values

    - #### IMWRITE_EXR_TYPE

          public static final int IMWRITE_EXR_TYPE

      See Also:
        Constant Field Values

    - #### IMWRITE_WEBP_QUALITY

          public static final int IMWRITE_WEBP_QUALITY

      See Also:
        Constant Field Values

    - #### IMWRITE_PAM_TUPLETYPE

          public static final int IMWRITE_PAM_TUPLETYPE

      See Also:
        Constant Field Values

    - #### IMWRITE_TIFF_RESUNIT

          public static final int IMWRITE_TIFF_RESUNIT

      See Also:
        Constant Field Values

    - #### IMWRITE_TIFF_XDPI

          public static final int IMWRITE_TIFF_XDPI

      See Also:
        Constant Field Values

    - #### IMWRITE_TIFF_YDPI

          public static final int IMWRITE_TIFF_YDPI

      See Also:
        Constant Field Values

    - #### IMWRITE_TIFF_COMPRESSION

          public static final int IMWRITE_TIFF_COMPRESSION

      See Also:
        Constant Field Values

    - #### IMWRITE_JPEG2000_COMPRESSION_X1000

          public static final int IMWRITE_JPEG2000_COMPRESSION_X1000

      See Also:
        Constant Field Values

    - #### IMWRITE_EXR_TYPE_HALF

          public static final int IMWRITE_EXR_TYPE_HALF

      See Also:
        Constant Field Values

    - #### IMWRITE_EXR_TYPE_FLOAT

          public static final int IMWRITE_EXR_TYPE_FLOAT

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY_DEFAULT

          public static final int IMWRITE_PNG_STRATEGY_DEFAULT

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY_FILTERED

          public static final int IMWRITE_PNG_STRATEGY_FILTERED

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY

          public static final int IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY_RLE

          public static final int IMWRITE_PNG_STRATEGY_RLE

      See Also:
        Constant Field Values

    - #### IMWRITE_PNG_STRATEGY_FIXED

          public static final int IMWRITE_PNG_STRATEGY_FIXED

      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### Imgcodecs

          public Imgcodecs()

  - ### Method Detail

    - #### imdecode

          public static Mat imdecode​(Mat buf,
                                     int flags)

      Reads an image from a buffer in memory. The function imdecode reads an image from the specified buffer in the memory. If the buffer is too short or contains invalid data, the function returns an empty matrix ( Mat::data==NULL ). See cv::imread for the list of supported formats and flags description. Note: In the case of color images, the decoded images will have the channels stored in B G R order.
      Parameters:
        `buf` - Input array or vector of bytes.
        `flags` - The same flags as in cv::imread, see cv::ImreadModes.
      Returns:
        automatically generated

    - #### imread

          public static Mat imread​(java.lang.String filename,
                                   int flags)

      Loads an image from a file. imread The function imread loads an image from the specified file and returns it. If the image cannot be read (because of missing file, improper permissions, unsupported or invalid format), the function returns an empty matrix ( Mat::data==NULL ). Currently, the following file formats are supported:
      - Windows bitmaps - \*.bmp, \*.dib (always supported)
      - JPEG files - \*.jpeg, \*.jpg, \*.jpe (see the *Note* section)
      - JPEG 2000 files - \*.jp2 (see the *Note* section)
      - Portable Network Graphics - \*.png (see the *Note* section)
      - WebP - \*.webp (see the *Note* section)
      - Portable image format - \*.pbm, \*.pgm, \*.ppm \*.pxm, \*.pnm (always supported)
      - PFM files - \*.pfm (see the *Note* section)
      - Sun rasters - \*.sr, \*.ras (always supported)
      - TIFF files - \*.tiff, \*.tif (see the *Note* section)
      - OpenEXR Image files - \*.exr (see the *Note* section)
      - Radiance HDR - \*.hdr, \*.pic (always supported)
      - Raster and Vector geospatial data supported by GDAL (see the *Note* section)
      Note:
      - The function determines the type of an image by the content, not by the file extension.
      - In the case of color images, the decoded images will have the channels stored in B G R order.
      - When using IMREAD_GRAYSCALE, the codec's internal grayscale conversion will be used, if available. Results may differ to the output of cvtColor()
      - On Microsoft Windows\* OS and MacOSX\*, the codecs shipped with an OpenCV image (libjpeg, libpng, libtiff, and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs, and TIFFs. On MacOSX, there is also an option to use native MacOSX image readers. But beware that currently these native image loaders give images with different pixel values because of the color management embedded into MacOSX.
      - On Linux\*, BSD flavors and other Unix-like open-source operating systems, OpenCV looks for codecs supplied with an OS image. Install the relevant packages (do not forget the development files, for example, "libjpeg-dev", in Debian\* and Ubuntu\*) to get the codec support or turn on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
      - In the case you set *WITH_GDAL* flag to true in CMake and REF: IMREAD_LOAD_GDAL to load the image, then the [GDAL](http://www.gdal.org) driver will be used in order to decode the image, supporting the following formats: [Raster](http://www.gdal.org/formats_list.html), [Vector](http://www.gdal.org/ogr_formats.html).
      - If EXIF information is embedded in the image file, the EXIF orientation will be taken into account and thus the image will be rotated accordingly except if the flags REF: IMREAD_IGNORE_ORIENTATION or REF: IMREAD_UNCHANGED are passed.
      - Use the IMREAD_UNCHANGED flag to keep the floating point values from PFM image.
      - By default number of pixels must be less than 2^30. Limit can be set using system variable OPENCV_IO_MAX_IMAGE_PIXELS
      Parameters:
        `filename` - Name of file to be loaded.
        `flags` - Flag that can take values of cv::ImreadModes
      Returns:
        automatically generated

    - #### imread

          public static Mat imread​(java.lang.String filename)

      Loads an image from a file. imread The function imread loads an image from the specified file and returns it. If the image cannot be read (because of missing file, improper permissions, unsupported or invalid format), the function returns an empty matrix ( Mat::data==NULL ). Currently, the following file formats are supported:
      - Windows bitmaps - \*.bmp, \*.dib (always supported)
      - JPEG files - \*.jpeg, \*.jpg, \*.jpe (see the *Note* section)
      - JPEG 2000 files - \*.jp2 (see the *Note* section)
      - Portable Network Graphics - \*.png (see the *Note* section)
      - WebP - \*.webp (see the *Note* section)
      - Portable image format - \*.pbm, \*.pgm, \*.ppm \*.pxm, \*.pnm (always supported)
      - PFM files - \*.pfm (see the *Note* section)
      - Sun rasters - \*.sr, \*.ras (always supported)
      - TIFF files - \*.tiff, \*.tif (see the *Note* section)
      - OpenEXR Image files - \*.exr (see the *Note* section)
      - Radiance HDR - \*.hdr, \*.pic (always supported)
      - Raster and Vector geospatial data supported by GDAL (see the *Note* section)
      Note:
      - The function determines the type of an image by the content, not by the file extension.
      - In the case of color images, the decoded images will have the channels stored in B G R order.
      - When using IMREAD_GRAYSCALE, the codec's internal grayscale conversion will be used, if available. Results may differ to the output of cvtColor()
      - On Microsoft Windows\* OS and MacOSX\*, the codecs shipped with an OpenCV image (libjpeg, libpng, libtiff, and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs, and TIFFs. On MacOSX, there is also an option to use native MacOSX image readers. But beware that currently these native image loaders give images with different pixel values because of the color management embedded into MacOSX.
      - On Linux\*, BSD flavors and other Unix-like open-source operating systems, OpenCV looks for codecs supplied with an OS image. Install the relevant packages (do not forget the development files, for example, "libjpeg-dev", in Debian\* and Ubuntu\*) to get the codec support or turn on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
      - In the case you set *WITH_GDAL* flag to true in CMake and REF: IMREAD_LOAD_GDAL to load the image, then the [GDAL](http://www.gdal.org) driver will be used in order to decode the image, supporting the following formats: [Raster](http://www.gdal.org/formats_list.html), [Vector](http://www.gdal.org/ogr_formats.html).
      - If EXIF information is embedded in the image file, the EXIF orientation will be taken into account and thus the image will be rotated accordingly except if the flags REF: IMREAD_IGNORE_ORIENTATION or REF: IMREAD_UNCHANGED are passed.
      - Use the IMREAD_UNCHANGED flag to keep the floating point values from PFM image.
      - By default number of pixels must be less than 2^30. Limit can be set using system variable OPENCV_IO_MAX_IMAGE_PIXELS
      Parameters:
        `filename` - Name of file to be loaded.
      Returns:
        automatically generated

    - #### haveImageReader

          public static boolean haveImageReader​(java.lang.String filename)

      Returns true if the specified image can be decoded by OpenCV
      Parameters:
        `filename` - File name of the image
      Returns:
        automatically generated

    - #### haveImageWriter

          public static boolean haveImageWriter​(java.lang.String filename)

      Returns true if an image with the specified filename can be encoded by OpenCV
      Parameters:
        `filename` - File name of the image
      Returns:
        automatically generated

    - #### imencode

          public static boolean imencode​(java.lang.String ext,
                                         Mat img,
                                         MatOfByte buf,
                                         MatOfInt params)

      Encodes an image into a memory buffer. The function imencode compresses the image and stores it in the memory buffer that is resized to fit the result. See cv::imwrite for the list of supported formats and flags description.
      Parameters:
        `ext` - File extension that defines the output format.
        `img` - Image to be written.
        `buf` - Output buffer resized to fit the compressed image.
        `params` - Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.
      Returns:
        automatically generated

    - #### imencode

          public static boolean imencode​(java.lang.String ext,
                                         Mat img,
                                         MatOfByte buf)

      Encodes an image into a memory buffer. The function imencode compresses the image and stores it in the memory buffer that is resized to fit the result. See cv::imwrite for the list of supported formats and flags description.
      Parameters:
        `ext` - File extension that defines the output format.
        `img` - Image to be written.
        `buf` - Output buffer resized to fit the compressed image.
      Returns:
        automatically generated

    - #### imreadmulti

          public static boolean imreadmulti​(java.lang.String filename,
                                            java.util.List<Mat> mats,
                                            int flags)

      Loads a multi-page image from a file. The function imreadmulti loads a multi-page image from the specified file into a vector of Mat objects.
      Parameters:
        `filename` - Name of file to be loaded.
        `flags` - Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR.
        `mats` - A vector of Mat objects holding each page, if more than one. SEE: cv::imread
      Returns:
        automatically generated

    - #### imreadmulti

          public static boolean imreadmulti​(java.lang.String filename,
                                            java.util.List<Mat> mats)

      Loads a multi-page image from a file. The function imreadmulti loads a multi-page image from the specified file into a vector of Mat objects.
      Parameters:
        `filename` - Name of file to be loaded.
        `mats` - A vector of Mat objects holding each page, if more than one. SEE: cv::imread
      Returns:
        automatically generated

    - #### imwrite

          public static boolean imwrite​(java.lang.String filename,
                                        Mat img,
                                        MatOfInt params)

      Saves an image to a specified file. The function imwrite saves the image to the specified file. The image format is chosen based on the filename extension (see cv::imread for the list of extensions). In general, only 8-bit single-channel or 3-channel (with 'BGR' channel order) images can be saved using this function, with these exceptions:
      - 16-bit unsigned (CV_16U) images can be saved in the case of PNG, JPEG 2000, and TIFF formats
      - 32-bit float (CV_32F) images can be saved in PFM, TIFF, OpenEXR, and Radiance HDR formats; 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
      - PNG images with an alpha channel can be saved using this function. To do this, create 8-bit (or 16-bit) 4-channel image BGRA, where the alpha channel goes last. Fully transparent pixels should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535 (see the code sample below).
      If the format, depth or channel order is different, use Mat::convertTo and cv::cvtColor to convert it before saving. Or, use the universal FileStorage I/O functions to save the image to XML or YAML format. The sample below shows how to create a BGRA image and save it to a PNG file. It also demonstrates how to set custom compression parameters: INCLUDE: snippets/imgcodecs_imwrite.cpp
      Parameters:
        `filename` - Name of the file.
        `img` - Image to be saved.
        `params` - Format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ... .) see cv::ImwriteFlags
      Returns:
        automatically generated

    - #### imwrite

          public static boolean imwrite​(java.lang.String filename,
                                        Mat img)

      Saves an image to a specified file. The function imwrite saves the image to the specified file. The image format is chosen based on the filename extension (see cv::imread for the list of extensions). In general, only 8-bit single-channel or 3-channel (with 'BGR' channel order) images can be saved using this function, with these exceptions:
      - 16-bit unsigned (CV_16U) images can be saved in the case of PNG, JPEG 2000, and TIFF formats
      - 32-bit float (CV_32F) images can be saved in PFM, TIFF, OpenEXR, and Radiance HDR formats; 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
      - PNG images with an alpha channel can be saved using this function. To do this, create 8-bit (or 16-bit) 4-channel image BGRA, where the alpha channel goes last. Fully transparent pixels should have alpha set to 0, fully opaque pixels should have alpha set to 255/65535 (see the code sample below).
      If the format, depth or channel order is different, use Mat::convertTo and cv::cvtColor to convert it before saving. Or, use the universal FileStorage I/O functions to save the image to XML or YAML format. The sample below shows how to create a BGRA image and save it to a PNG file. It also demonstrates how to set custom compression parameters: INCLUDE: snippets/imgcodecs_imwrite.cpp
      Parameters:
        `filename` - Name of the file.
        `img` - Image to be saved.
      Returns:
        automatically generated