Package org.opencv.imgcodecs
Class Imgcodecs
- java.lang.Object
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- org.opencv.imgcodecs.Imgcodecs
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public class Imgcodecs extends java.lang.Object
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Field Summary
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Constructor Summary
Constructors Constructor Description Imgcodecs()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static boolean
haveImageReader(java.lang.String filename)
Checks if the specified image file can be decoded by OpenCV.static boolean
haveImageWriter(java.lang.String filename)
Checks if the specified image file or specified file extension can be encoded by OpenCV.static long
imcount(java.lang.String filename)
Returns the number of images inside the given file The function imcount returns the number of pages in a multi-page image (e.g.static long
imcount(java.lang.String filename, int flags)
Returns the number of images inside the given file The function imcount returns the number of pages in a multi-page image (e.g.static Mat
imdecode(Mat buf, int flags)
Reads an image from a buffer in memory.static boolean
imdecodemulti(Mat buf, int flags, java.util.List<Mat> mats)
Reads a multi-page image from a buffer in memory.static boolean
imdecodemulti(Mat buf, int flags, java.util.List<Mat> mats, Range range)
Reads a multi-page 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 boolean
imencodemulti(java.lang.String ext, java.util.List<Mat> imgs, MatOfByte buf)
Encodes array of images into a memory buffer.static boolean
imencodemulti(java.lang.String ext, java.util.List<Mat> imgs, MatOfByte buf, MatOfInt params)
Encodes array of images 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 void
imread(java.lang.String filename, Mat dst)
Loads an image from a file.static void
imread(java.lang.String filename, Mat dst, 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
imreadmulti(java.lang.String filename, java.util.List<Mat> mats, int start, int count)
Loads images of a multi-page image from a file.static boolean
imreadmulti(java.lang.String filename, java.util.List<Mat> mats, int start, int count, int flags)
Loads images of 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.static boolean
imwritemulti(java.lang.String filename, java.util.List<Mat> img)
static boolean
imwritemulti(java.lang.String filename, java.util.List<Mat> img, MatOfInt params)
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Field Detail
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IMREAD_UNCHANGED
public static final int IMREAD_UNCHANGED
- See Also:
- Constant Field Values
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IMREAD_GRAYSCALE
public static final int IMREAD_GRAYSCALE
- See Also:
- Constant Field Values
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IMREAD_COLOR_BGR
public static final int IMREAD_COLOR_BGR
- See Also:
- Constant Field Values
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IMREAD_COLOR
public static final int IMREAD_COLOR
- See Also:
- Constant Field Values
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IMREAD_ANYDEPTH
public static final int IMREAD_ANYDEPTH
- See Also:
- Constant Field Values
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IMREAD_ANYCOLOR
public static final int IMREAD_ANYCOLOR
- See Also:
- Constant Field Values
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IMREAD_LOAD_GDAL
public static final int IMREAD_LOAD_GDAL
- See Also:
- Constant Field Values
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IMREAD_REDUCED_GRAYSCALE_2
public static final int IMREAD_REDUCED_GRAYSCALE_2
- See Also:
- Constant Field Values
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IMREAD_REDUCED_COLOR_2
public static final int IMREAD_REDUCED_COLOR_2
- See Also:
- Constant Field Values
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IMREAD_REDUCED_GRAYSCALE_4
public static final int IMREAD_REDUCED_GRAYSCALE_4
- See Also:
- Constant Field Values
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IMREAD_REDUCED_COLOR_4
public static final int IMREAD_REDUCED_COLOR_4
- See Also:
- Constant Field Values
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IMREAD_REDUCED_GRAYSCALE_8
public static final int IMREAD_REDUCED_GRAYSCALE_8
- See Also:
- Constant Field Values
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IMREAD_REDUCED_COLOR_8
public static final int IMREAD_REDUCED_COLOR_8
- See Also:
- Constant Field Values
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IMREAD_IGNORE_ORIENTATION
public static final int IMREAD_IGNORE_ORIENTATION
- See Also:
- Constant Field Values
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IMREAD_COLOR_RGB
public static final int IMREAD_COLOR_RGB
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_NO
public static final int IMWRITE_EXR_COMPRESSION_NO
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_RLE
public static final int IMWRITE_EXR_COMPRESSION_RLE
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_ZIPS
public static final int IMWRITE_EXR_COMPRESSION_ZIPS
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_ZIP
public static final int IMWRITE_EXR_COMPRESSION_ZIP
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_PIZ
public static final int IMWRITE_EXR_COMPRESSION_PIZ
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_PXR24
public static final int IMWRITE_EXR_COMPRESSION_PXR24
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- Constant Field Values
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IMWRITE_EXR_COMPRESSION_B44
public static final int IMWRITE_EXR_COMPRESSION_B44
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_B44A
public static final int IMWRITE_EXR_COMPRESSION_B44A
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_DWAA
public static final int IMWRITE_EXR_COMPRESSION_DWAA
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION_DWAB
public static final int IMWRITE_EXR_COMPRESSION_DWAB
- See Also:
- Constant Field Values
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IMWRITE_EXR_TYPE_HALF
public static final int IMWRITE_EXR_TYPE_HALF
- See Also:
- Constant Field Values
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IMWRITE_EXR_TYPE_FLOAT
public static final int IMWRITE_EXR_TYPE_FLOAT
- See Also:
- Constant Field Values
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IMWRITE_JPEG_QUALITY
public static final int IMWRITE_JPEG_QUALITY
- See Also:
- Constant Field Values
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IMWRITE_JPEG_PROGRESSIVE
public static final int IMWRITE_JPEG_PROGRESSIVE
- See Also:
- Constant Field Values
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IMWRITE_JPEG_OPTIMIZE
public static final int IMWRITE_JPEG_OPTIMIZE
- See Also:
- Constant Field Values
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IMWRITE_JPEG_RST_INTERVAL
public static final int IMWRITE_JPEG_RST_INTERVAL
- See Also:
- Constant Field Values
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IMWRITE_JPEG_LUMA_QUALITY
public static final int IMWRITE_JPEG_LUMA_QUALITY
- See Also:
- Constant Field Values
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IMWRITE_JPEG_CHROMA_QUALITY
public static final int IMWRITE_JPEG_CHROMA_QUALITY
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR
public static final int IMWRITE_JPEG_SAMPLING_FACTOR
- See Also:
- Constant Field Values
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IMWRITE_PNG_COMPRESSION
public static final int IMWRITE_PNG_COMPRESSION
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY
public static final int IMWRITE_PNG_STRATEGY
- See Also:
- Constant Field Values
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IMWRITE_PNG_BILEVEL
public static final int IMWRITE_PNG_BILEVEL
- See Also:
- Constant Field Values
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IMWRITE_PXM_BINARY
public static final int IMWRITE_PXM_BINARY
- See Also:
- Constant Field Values
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IMWRITE_EXR_TYPE
public static final int IMWRITE_EXR_TYPE
- See Also:
- Constant Field Values
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IMWRITE_EXR_COMPRESSION
public static final int IMWRITE_EXR_COMPRESSION
- See Also:
- Constant Field Values
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IMWRITE_EXR_DWA_COMPRESSION_LEVEL
public static final int IMWRITE_EXR_DWA_COMPRESSION_LEVEL
- See Also:
- Constant Field Values
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IMWRITE_WEBP_QUALITY
public static final int IMWRITE_WEBP_QUALITY
- See Also:
- Constant Field Values
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IMWRITE_HDR_COMPRESSION
public static final int IMWRITE_HDR_COMPRESSION
- See Also:
- Constant Field Values
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IMWRITE_PAM_TUPLETYPE
public static final int IMWRITE_PAM_TUPLETYPE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_RESUNIT
public static final int IMWRITE_TIFF_RESUNIT
- See Also:
- Constant Field Values
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IMWRITE_TIFF_XDPI
public static final int IMWRITE_TIFF_XDPI
- See Also:
- Constant Field Values
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IMWRITE_TIFF_YDPI
public static final int IMWRITE_TIFF_YDPI
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION
public static final int IMWRITE_TIFF_COMPRESSION
- See Also:
- Constant Field Values
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IMWRITE_TIFF_ROWSPERSTRIP
public static final int IMWRITE_TIFF_ROWSPERSTRIP
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- Constant Field Values
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IMWRITE_TIFF_PREDICTOR
public static final int IMWRITE_TIFF_PREDICTOR
- See Also:
- Constant Field Values
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IMWRITE_JPEG2000_COMPRESSION_X1000
public static final int IMWRITE_JPEG2000_COMPRESSION_X1000
- See Also:
- Constant Field Values
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IMWRITE_AVIF_QUALITY
public static final int IMWRITE_AVIF_QUALITY
- See Also:
- Constant Field Values
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IMWRITE_AVIF_DEPTH
public static final int IMWRITE_AVIF_DEPTH
- See Also:
- Constant Field Values
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IMWRITE_AVIF_SPEED
public static final int IMWRITE_AVIF_SPEED
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- Constant Field Values
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IMWRITE_HDR_COMPRESSION_NONE
public static final int IMWRITE_HDR_COMPRESSION_NONE
- See Also:
- Constant Field Values
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IMWRITE_HDR_COMPRESSION_RLE
public static final int IMWRITE_HDR_COMPRESSION_RLE
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR_411
public static final int IMWRITE_JPEG_SAMPLING_FACTOR_411
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR_420
public static final int IMWRITE_JPEG_SAMPLING_FACTOR_420
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR_422
public static final int IMWRITE_JPEG_SAMPLING_FACTOR_422
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR_440
public static final int IMWRITE_JPEG_SAMPLING_FACTOR_440
- See Also:
- Constant Field Values
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IMWRITE_JPEG_SAMPLING_FACTOR_444
public static final int IMWRITE_JPEG_SAMPLING_FACTOR_444
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_NULL
public static final int IMWRITE_PAM_FORMAT_NULL
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_BLACKANDWHITE
public static final int IMWRITE_PAM_FORMAT_BLACKANDWHITE
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_GRAYSCALE
public static final int IMWRITE_PAM_FORMAT_GRAYSCALE
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA
public static final int IMWRITE_PAM_FORMAT_GRAYSCALE_ALPHA
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_RGB
public static final int IMWRITE_PAM_FORMAT_RGB
- See Also:
- Constant Field Values
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IMWRITE_PAM_FORMAT_RGB_ALPHA
public static final int IMWRITE_PAM_FORMAT_RGB_ALPHA
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY_DEFAULT
public static final int IMWRITE_PNG_STRATEGY_DEFAULT
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY_FILTERED
public static final int IMWRITE_PNG_STRATEGY_FILTERED
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY
public static final int IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY_RLE
public static final int IMWRITE_PNG_STRATEGY_RLE
- See Also:
- Constant Field Values
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IMWRITE_PNG_STRATEGY_FIXED
public static final int IMWRITE_PNG_STRATEGY_FIXED
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_NONE
public static final int IMWRITE_TIFF_COMPRESSION_NONE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITTRLE
public static final int IMWRITE_TIFF_COMPRESSION_CCITTRLE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITTFAX3
public static final int IMWRITE_TIFF_COMPRESSION_CCITTFAX3
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- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITT_T4
public static final int IMWRITE_TIFF_COMPRESSION_CCITT_T4
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- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITTFAX4
public static final int IMWRITE_TIFF_COMPRESSION_CCITTFAX4
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITT_T6
public static final int IMWRITE_TIFF_COMPRESSION_CCITT_T6
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_LZW
public static final int IMWRITE_TIFF_COMPRESSION_LZW
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_OJPEG
public static final int IMWRITE_TIFF_COMPRESSION_OJPEG
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_JPEG
public static final int IMWRITE_TIFF_COMPRESSION_JPEG
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_T85
public static final int IMWRITE_TIFF_COMPRESSION_T85
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_T43
public static final int IMWRITE_TIFF_COMPRESSION_T43
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_NEXT
public static final int IMWRITE_TIFF_COMPRESSION_NEXT
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_CCITTRLEW
public static final int IMWRITE_TIFF_COMPRESSION_CCITTRLEW
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_PACKBITS
public static final int IMWRITE_TIFF_COMPRESSION_PACKBITS
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_THUNDERSCAN
public static final int IMWRITE_TIFF_COMPRESSION_THUNDERSCAN
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_IT8CTPAD
public static final int IMWRITE_TIFF_COMPRESSION_IT8CTPAD
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_IT8LW
public static final int IMWRITE_TIFF_COMPRESSION_IT8LW
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_IT8MP
public static final int IMWRITE_TIFF_COMPRESSION_IT8MP
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_IT8BL
public static final int IMWRITE_TIFF_COMPRESSION_IT8BL
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_PIXARFILM
public static final int IMWRITE_TIFF_COMPRESSION_PIXARFILM
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_PIXARLOG
public static final int IMWRITE_TIFF_COMPRESSION_PIXARLOG
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_DEFLATE
public static final int IMWRITE_TIFF_COMPRESSION_DEFLATE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_ADOBE_DEFLATE
public static final int IMWRITE_TIFF_COMPRESSION_ADOBE_DEFLATE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_DCS
public static final int IMWRITE_TIFF_COMPRESSION_DCS
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_JBIG
public static final int IMWRITE_TIFF_COMPRESSION_JBIG
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_SGILOG
public static final int IMWRITE_TIFF_COMPRESSION_SGILOG
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_SGILOG24
public static final int IMWRITE_TIFF_COMPRESSION_SGILOG24
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_JP2000
public static final int IMWRITE_TIFF_COMPRESSION_JP2000
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_LERC
public static final int IMWRITE_TIFF_COMPRESSION_LERC
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_LZMA
public static final int IMWRITE_TIFF_COMPRESSION_LZMA
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_ZSTD
public static final int IMWRITE_TIFF_COMPRESSION_ZSTD
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_WEBP
public static final int IMWRITE_TIFF_COMPRESSION_WEBP
- See Also:
- Constant Field Values
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IMWRITE_TIFF_COMPRESSION_JXL
public static final int IMWRITE_TIFF_COMPRESSION_JXL
- See Also:
- Constant Field Values
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IMWRITE_TIFF_PREDICTOR_NONE
public static final int IMWRITE_TIFF_PREDICTOR_NONE
- See Also:
- Constant Field Values
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IMWRITE_TIFF_PREDICTOR_HORIZONTAL
public static final int IMWRITE_TIFF_PREDICTOR_HORIZONTAL
- See Also:
- Constant Field Values
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IMWRITE_TIFF_PREDICTOR_FLOATINGPOINT
public static final int IMWRITE_TIFF_PREDICTOR_FLOATINGPOINT
- See Also:
- Constant Field Values
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Method Detail
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imread
public static Mat imread(java.lang.String filename, int flags)
Loads an image from a file. imread Theimread
function loads an image from the specified file and returns OpenCV matrix. If the image cannot be read (because of a missing file, improper permissions, or unsupported/invalid format), the function returns an empty matrix. 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)
- AVIF - \*.avif (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)
- The function determines the type of an image by its 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 from the output of cvtColor().
- On Microsoft Windows\* and Mac OS\*, the codecs shipped with OpenCV (libjpeg, libpng, libtiff, and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs, and TIFFs. On Mac OS, there is also an option to use native Mac OS image readers. However, beware that currently these native image loaders give images with different pixel values because of the color management embedded into Mac OS.
- On Linux\*, BSD flavors, and other Unix-like open-source operating systems, OpenCV looks for codecs supplied with the OS. Ensure the relevant packages are installed (including development files, such as "libjpeg-dev" in Debian\* and Ubuntu\*) to get codec support, or turn on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
- If the *WITH_GDAL* flag is set to true in CMake and REF: IMREAD_LOAD_GDAL is used to load the image, the [GDAL](http://www.gdal.org) driver will be used to decode the image, supporting [Raster](http://www.gdal.org/formats_list.html) and [Vector](http://www.gdal.org/ogr_formats.html) formats.
- 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 unless the flags REF: IMREAD_IGNORE_ORIENTATION or REF: IMREAD_UNCHANGED are passed.
- Use the IMREAD_UNCHANGED flag to preserve the floating-point values from PFM images.
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By default, the number of pixels must be less than 2^30. This limit can be changed by setting
the environment variable
OPENCV_IO_MAX_IMAGE_PIXELS
. See REF: tutorial_env_reference.
- Parameters:
filename
- Name of the file to be loaded.flags
- Flag that can take values ofcv::ImreadModes
.- Returns:
- automatically generated
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imread
public static Mat imread(java.lang.String filename)
Loads an image from a file. imread Theimread
function loads an image from the specified file and returns OpenCV matrix. If the image cannot be read (because of a missing file, improper permissions, or unsupported/invalid format), the function returns an empty matrix. 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)
- AVIF - \*.avif (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)
- The function determines the type of an image by its 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 from the output of cvtColor().
- On Microsoft Windows\* and Mac OS\*, the codecs shipped with OpenCV (libjpeg, libpng, libtiff, and libjasper) are used by default. So, OpenCV can always read JPEGs, PNGs, and TIFFs. On Mac OS, there is also an option to use native Mac OS image readers. However, beware that currently these native image loaders give images with different pixel values because of the color management embedded into Mac OS.
- On Linux\*, BSD flavors, and other Unix-like open-source operating systems, OpenCV looks for codecs supplied with the OS. Ensure the relevant packages are installed (including development files, such as "libjpeg-dev" in Debian\* and Ubuntu\*) to get codec support, or turn on the OPENCV_BUILD_3RDPARTY_LIBS flag in CMake.
- If the *WITH_GDAL* flag is set to true in CMake and REF: IMREAD_LOAD_GDAL is used to load the image, the [GDAL](http://www.gdal.org) driver will be used to decode the image, supporting [Raster](http://www.gdal.org/formats_list.html) and [Vector](http://www.gdal.org/ogr_formats.html) formats.
- 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 unless the flags REF: IMREAD_IGNORE_ORIENTATION or REF: IMREAD_UNCHANGED are passed.
- Use the IMREAD_UNCHANGED flag to preserve the floating-point values from PFM images.
-
By default, the number of pixels must be less than 2^30. This limit can be changed by setting
the environment variable
OPENCV_IO_MAX_IMAGE_PIXELS
. See REF: tutorial_env_reference.
- Parameters:
filename
- Name of the file to be loaded.- Returns:
- automatically generated
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imread
public static void imread(java.lang.String filename, Mat dst, int flags)
Loads an image from a file. This 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.- Parameters:
filename
- Name of file to be loaded.dst
- object in which the image will be loaded.flags
- Flag that can take values of cv::ImreadModes Note: The 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.
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imread
public static void imread(java.lang.String filename, Mat dst)
Loads an image from a file. This 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.- Parameters:
filename
- Name of file to be loaded.dst
- object in which the image will be loaded. Note: The 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.
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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.mats
- A vector of Mat objects holding each page.flags
- Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR. SEE: cv::imread- Returns:
- automatically generated
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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. SEE: cv::imread- Returns:
- automatically generated
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imreadmulti
public static boolean imreadmulti(java.lang.String filename, java.util.List<Mat> mats, int start, int count, int flags)
Loads images of a multi-page image from a file. The function imreadmulti loads a specified range from 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.start
- Start index of the image to loadcount
- Count number of images to loadflags
- Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR. SEE: cv::imread- Returns:
- automatically generated
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imreadmulti
public static boolean imreadmulti(java.lang.String filename, java.util.List<Mat> mats, int start, int count)
Loads images of a multi-page image from a file. The function imreadmulti loads a specified range from 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.start
- Start index of the image to loadcount
- Count number of images to load SEE: cv::imread- Returns:
- automatically generated
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imcount
public static long imcount(java.lang.String filename, int flags)
Returns the number of images inside the given file The 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. If the image cannot be decoded, 0 is returned.- Parameters:
filename
- Name of file to be loaded.flags
- Flag that can take values of cv::ImreadModes, default with cv::IMREAD_ANYCOLOR. 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.- Returns:
- automatically generated
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imcount
public static long imcount(java.lang.String filename)
Returns the number of images inside the given file The 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. If the image cannot be decoded, 0 is returned.- Parameters:
filename
- Name of file to be loaded. 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.- Returns:
- automatically generated
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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 unsigned (CV_8U) single-channel or 3-channel (with 'BGR' channel order) images can be saved using this function, with these exceptions:-
With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
- 8-bit unsigned (CV_8U) images are not supported.
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With Radiance HDR encoder, non 64-bit float (CV_64F) images can be saved.
- All images will be converted to 32-bit float (CV_32F).
- With JPEG 2000 encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- With PAM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
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With PNG encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- 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).
- With PGM/PPM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
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With TIFF encoder, 8-bit unsigned (CV_8U), 16-bit unsigned (CV_16U),
32-bit float (CV_32F) and 64-bit float (CV_64F) images can be saved.
- Multiple images (vector of Mat) can be saved in TIFF format (see the code sample below).
- 32-bit float 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
- Parameters:
filename
- Name of the file.img
- (Mat or vector of Mat) Image or Images to be saved.params
- Format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ... .) see cv::ImwriteFlags- Returns:
- automatically generated
-
With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
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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 unsigned (CV_8U) single-channel or 3-channel (with 'BGR' channel order) images can be saved using this function, with these exceptions:-
With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
- 8-bit unsigned (CV_8U) images are not supported.
-
With Radiance HDR encoder, non 64-bit float (CV_64F) images can be saved.
- All images will be converted to 32-bit float (CV_32F).
- With JPEG 2000 encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- With PAM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
-
With PNG encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- 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).
- With PGM/PPM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
-
With TIFF encoder, 8-bit unsigned (CV_8U), 16-bit unsigned (CV_16U),
32-bit float (CV_32F) and 64-bit float (CV_64F) images can be saved.
- Multiple images (vector of Mat) can be saved in TIFF format (see the code sample below).
- 32-bit float 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
- Parameters:
filename
- Name of the file.img
- (Mat or vector of Mat) Image or Images to be saved.- Returns:
- automatically generated
-
With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
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imwritemulti
public static boolean imwritemulti(java.lang.String filename, java.util.List<Mat> img, MatOfInt params)
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imwritemulti
public static boolean imwritemulti(java.lang.String filename, java.util.List<Mat> img)
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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
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imdecodemulti
public static boolean imdecodemulti(Mat buf, int flags, java.util.List<Mat> mats, Range range)
Reads a multi-page image from a buffer in memory. The function imdecodemulti reads a multi-page image from the specified buffer in the memory. If the buffer is too short or contains invalid data, the function returns false. See cv::imreadmulti 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.mats
- A vector of Mat objects holding each page, if more than one.range
- A continuous selection of pages.- Returns:
- automatically generated
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imdecodemulti
public static boolean imdecodemulti(Mat buf, int flags, java.util.List<Mat> mats)
Reads a multi-page image from a buffer in memory. The function imdecodemulti reads a multi-page image from the specified buffer in the memory. If the buffer is too short or contains invalid data, the function returns false. See cv::imreadmulti 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.mats
- A vector of Mat objects holding each page, if more than one.- Returns:
- automatically generated
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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. Must include a leading period.img
- Image to be compressed.buf
- Output buffer resized to fit the compressed image.params
- Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.- Returns:
- automatically generated
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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. Must include a leading period.img
- Image to be compressed.buf
- Output buffer resized to fit the compressed image.- Returns:
- automatically generated
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imencodemulti
public static boolean imencodemulti(java.lang.String ext, java.util.List<Mat> imgs, MatOfByte buf, MatOfInt params)
Encodes array of images into a memory buffer. The function is analog to cv::imencode for in-memory multi-page image compression. See cv::imwrite for the list of supported formats and flags description.- Parameters:
ext
- File extension that defines the output format. Must include a leading period.imgs
- Vector of images to be written.buf
- Output buffer resized to fit the compressed data.params
- Format-specific parameters. See cv::imwrite and cv::ImwriteFlags.- Returns:
- automatically generated
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imencodemulti
public static boolean imencodemulti(java.lang.String ext, java.util.List<Mat> imgs, MatOfByte buf)
Encodes array of images into a memory buffer. The function is analog to cv::imencode for in-memory multi-page image compression. See cv::imwrite for the list of supported formats and flags description.- Parameters:
ext
- File extension that defines the output format. Must include a leading period.imgs
- Vector of images to be written.buf
- Output buffer resized to fit the compressed data.- Returns:
- automatically generated
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haveImageReader
public static boolean haveImageReader(java.lang.String filename)
Checks if the specified image file can be decoded by OpenCV. The function haveImageReader checks if OpenCV is capable of reading the specified file. This can be useful for verifying support for a given image format before attempting to load an image.- Parameters:
filename
- The name of the file to be checked.- Returns:
- true if an image reader for the specified file is available and the file can be opened, false otherwise. Note: The function checks the availability of image codecs that are either built into OpenCV or dynamically loaded. It does not check for the actual existence of the file but rather the ability to read the specified file type. If the file cannot be opened or the format is unsupported, the function will return false. SEE: cv::haveImageWriter, cv::imread, cv::imdecode
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haveImageWriter
public static boolean haveImageWriter(java.lang.String filename)
Checks if the specified image file or specified file extension can be encoded by OpenCV. The function haveImageWriter checks if OpenCV is capable of writing images with the specified file extension. This can be useful for verifying support for a given image format before attempting to save an image.- Parameters:
filename
- The name of the file or the file extension (e.g., ".jpg", ".png"). It is recommended to provide the file extension rather than the full file name.- Returns:
- true if an image writer for the specified extension is available, false otherwise. Note: The function checks the availability of image codecs that are either built into OpenCV or dynamically loaded. It does not check for the actual existence of the file but rather the ability to write files of the given type. SEE: cv::haveImageReader, cv::imwrite, cv::imencode
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