libtiff - introduction to libtiff, a library for reading and writing TIFF files
cc file.c -ltiff
libtiff is a library for reading and writing data files encoded with the Tag Image File format, Revision 6.0 (or revision 5.0 or revision 4.0). This file format is suitable for archiving multi-color and monochromatic image data.
The library supports several compression algorithms, as indicated by the Compression field, including: no compression (1), CCITT 1D Huffman compression (2), CCITT Group 3 Facsimile compression (3), CCITT Group 4 Facsimile compression (4), Lempel-Ziv & Welch compression (5), baseline JPEG compression (7), word-aligned 1D Huffman compression (32771), and PackBits compression (32773). In addition, several nonstandard compression algorithms are supported: the 4-bit compression algorithm used by the ThunderScan program (32809) (decompression only), NeXTs 2-bit compression algorithm (32766) (decompression only), an experimental LZ-style algorithm known as Deflate (32946), and an experimental CIE LogLuv compression scheme designed for images with high dynamic range (32845 for LogL and 32845 for LogLuv). Directory information may be in either little- or big-endian byte order-byte swapping is automatically done by the library. Data bit ordering may be either Most Significant Bit ( MSB ) to Least Significant Bit ( LSB ) or LSB to MSB. Finally, the library does not support files in which the BitsPerSample, Compression, MinSampleValue, or MaxSampleValue fields are defined differently on a per-sample basis (in Rev. 6.0 the Compression tag is not defined on a per-sample basis, so this is immaterial).
The library makes extensive use of C typedefs to promote portability. Two sets of typedefs are used, one for communication with clients of the library and one for internal data structures and parsing of the TIFF format. The following typedefs are exposed to users either through function definitions or through parameters passed through the varargs interfaces.
typedef unsigned short uint16; 16-bit unsigned integer typedef unsigned <thing> uint32; 32-bit unsigned integer
typedef unsigned int ttag_t; directory tag typedef uint16 tdir_t; directory index typedef uint16 tsample_t; sample number typedef uint32 tstrip_t; strip number typedef uint32 ttile_t; tile number typedef int32 tsize_t; i/o size in bytes typedef void* tdata_t; image data ref typedef void* thandle_t; client data handle typedef int32 toff_t; file offset
Note that tstrip_t, ttile_t, and tsize_t are constrained to be no more than 32-bit quantities by 32-bit fields they are stored in in the TIFF image. Likewise tsample_t is limited by the 16-bit field used to store the SamplesPerPixel tag. tdir_t constrains the maximum number of IFDs that may appear in an image and may be an arbitrary size (w/o penalty). ttag_t must be either int, unsigned int, pointer, or double because the library uses a varargs interface and ANSI C restricts the type of the parameter before an ellipsis to be a promoted type. toff_t is defined as int32 because TIFF file offsets are (unsigned) 32-bit quantities. A signed value is used because some interfaces return -1 on error. Finally, note that user-specified data references are passed as opaque handles and only cast at the lowest layers where their type is presumed.
The following routines are part of the library. Consult specific manual pages for details on their operation. The manual page names listed below are for systems where the full function names can not be encoded in the filesystem; on most systems doing man function-name will work.
Name Appears on PageDescription
TIFFCheckpointDirectory writedir.3twrites the current state of the directory TIFFCheckTile tile.3t very x,y,z,sample is within image TIFFCIELabToRGBInit color.3t initialize CIE L*a*b* 1976 to RGB conversion state TIFFCIELabToXYZ color.3t perform CIE L*a*b* 1976 to CIE XYZ conversion TIFFClientOpen open.3t open a file for reading or writing TIFFClose close.3t close an open file TIFFComputeStrip strip.3t return strip containing y,sample TIFFComputeTile tile.3t return tile containing x,y,z,sample TIFFCurrentDirectory query.3t return index of current directory TIFFCurrentRow query.3t return index of current scanline TIFFCurrentStrip query.3t return index of current strip TIFFCurrentTile query.3t return index of current tile TIFFDataWidth width.3t return the size of TIFF data types TIFFError error.3t library error handler TIFFFdOpen open.3t open a file for reading or writing TIFFFileName query.3t return name of open file TIFFFileno query.3t return open file descriptor TIFFFindCODEC codec.3t find standard codec for the specific scheme TIFFFlush flush.3t flush all pending writes TIFFFlushData flush.3t flush pending data writes TIFFGetBitRevTable swab.3t return bit reversal table TIFFGetField getfield.3t return tag value in current directory TIFFGetFieldDefaulted getfield.3treturn tag value in current directory TIFFGetMode query.3t return open file mode TIFFGetVersion query.3t return library version string TIFFIsCODECConfigured codec.3tcheck, whether we have working codec TIFFIsTiled query.3t return true if image data is tiled TIFFIsByteSwapped query.3t return true if image data is byte-swapped TIFFNumberOfStrips strip.3t return number of strips in an image TIFFNumberOfTiles tile.3t return number of tiles in an image TIFFOpen open.3t open a file for reading or writing TIFFPrintDirectory print.3t print description of the current directory TIFFReadBufferSetup rdbuf.3t specify i/o buffer for reading TIFFReadDirectory readdir.3t read the next directory TIFFReadEncodedStrip rdestrip.3t read and decode a strip of data TIFFReadEncodedTile rdetile.3t read and decode a tile of data TIFFReadRawStrip rdrstrip.3t read a raw strip of data TIFFReadRawTile rdrtile.3t read a raw tile of data TIFFReadRGBAImage rdimage.3t read an image into a fixed format raster TIFFReadScanline readline.3t read and decode a row of data TIFFReadTile readtile.3t read and decode a tile of data TIFFRegisterCODEC codec.3t override standard codec for the specific scheme TIFFReverseBits swab.3t reverse bits in an array of bytes TIFFRGBAImageBegin rgbaimage.3t setup decoder state for TIFFRGBAImageGet TIFFRGBAImageEnd rgbaimage.3t release TIFFRGBAImage decoder state TIFFRGBAImageGet rgbaimage.3t read and decode an image TIFFRGBAImageOK rgbaimage.3t is image readable by TIFFRGBAImageGet TIFFScanlineSize size.3t return size of a scanline TIFFSetDirectory setdir.3t set the current directory TIFFSetSubDirectory setdir.3t set the current directory TIFFSetErrorHandler error.3t set error handler function TIFFSetField setfield.3t set a tags value in the current directory TIFFSetWarningHandler error.3tset warning handler function TIFFStripSize strip.3t returns size of a strip TIFFRawStripSize strip.3t returns the number of bytes in a raw strip TIFFSwabShort swab.3t swap bytes of short TIFFSwabLong swab.3t swap bytes of long TIFFSwabArrayOfShort swab.3t swap bytes of an array of shorts TIFFSwabArrayOfLong swab.3t swap bytes of an array of longs TIFFTileRowSize size.3t return size of a row in a tile TIFFTileSize size.3t return size of a tile TIFFUnRegisterCODEC codec.3t unregisters the codec TIFFVGetField getfield.3t return tag value in current directory TIFFVGetFieldDefaulted getfield.3treturn tag value in current directory TIFFVSetField setfield.3t set a tags value in the current directory TIFFVStripSize strip.3t returns the number of bytes in a strip TIFFWarning warning.3t library warning handler TIFFWriteDirectory writedir.3t write the current directory TIFFWriteEncodedStrip wrestrip.3tcompress and write a strip of data TIFFWriteEncodedTile wretile.3t compress and write a tile of data TIFFWriteRawStrip wrrstrip.3t write a raw strip of data TIFFWriteRawTile wrrtile.3t write a raw tile of data TIFFWriteScanline writeline.3t write a scanline of data TIFFWriteTile wrrtile.3t compress and write a tile of data TIFFXYZToRGB color.3t perform CIE XYZ to RGB conversion TIFFYCbCrToRGBInit color.3t initialize YCbCr to RGB conversion state TIFFYCbCrtoRGB color.3t perform YCbCr to RGB conversion
The table below lists the TIFF tags that are recognized and handled by the library. If no use is indicated in the table, then the library reads and writes the tag, but does not use it internally. Note that some tags are meaningful only when a particular compression scheme is being used; e.g. Group3Options is only useful if Compression is set to CCITT Group 3 encoding. Tags of this sort are considered codec-specific tags and the library does not recognize them except when the Compression tag has been previously set to the relevant compression scheme.
Tag Name Value R/WLibrary Use/Notes
Artist 315 R/W BadFaxLines 326 R/W BitsPerSample 258 R/Wlots CellLength 265 parsed but ignored CellWidth 264 parsed but ignored CleanFaxData 327 R/W ColorMap 320 R/W ColorResponseUnit 300 parsed but ignored Compression 259 R/Wchoosing codec ConsecutiveBadFaxLines 328R/W Copyright 33432 R/W DataType 32996 Robsoleted by SampleFormat tag DateTime 306 R/W DocumentName 269 R/W DotRange 336 R/W ExtraSamples 338 R/Wlots FaxRecvParams 34908 R/W FaxSubAddress 34909 R/W FaxRecvTime 34910 R/W FillOrder 266 R/Wcontrol bit order FreeByteCounts 289 parsed but ignored FreeOffsets 288 parsed but ignored GrayResponseCurve 291 parsed but ignored GrayResponseUnit 290 parsed but ignored Group3Options 292 R/Wused by Group 3 codec Group4Options 293 R/W HostComputer 316 R/W ImageDepth 32997 R/Wtile/strip calculations ImageDescription 270 R/W ImageLength 257 R/Wlots ImageWidth 256 R/Wlots InkNames 333 R/W InkSet 332 R/W JPEGTables 347 R/Wused by JPEG codec Make 271 R/W Matteing 32995 Robsoleted by ExtraSamples tag MaxSampleValue 281 R/W MinSampleValue 280 R/W Model 272 R/W NewSubFileType 254 R/Wcalled SubFileType in spec NumberOfInks 334 R/W Orientation 274 R/W PageName 285 R/W PageNumber 297 R/W PhotometricInterpretation 262R/Wused by Group 3 and JPEG codecs PlanarConfiguration 284 R/Wdata i/o Predictor 317 R/Wused by LZW and Deflate codecs PrimaryChromacities 319 R/W ReferenceBlackWhite 532 R/W ResolutionUnit 296 R/Wused by Group 3 codec RowsPerStrip 278 R/Wdata i/o SampleFormat 339 R/W SamplesPerPixel 277 R/Wlots SMinSampleValue 340 R/W SMaxSampleValue 341 R/W Software 305 R/W StoNits 37439 R/W StripByteCounts 279 R/Wdata i/o StripOffsets 273 R/Wdata i/o SubFileType 255 R/Wcalled OSubFileType in spec TargetPrinter 337 R/W Thresholding 263 R/W TileByteCounts 324 R/Wdata i/o TileDepth 32998 R/Wtile/strip calculations TileLength 323 R/Wdata i/o TileOffsets 324 R/Wdata i/o TileWidth 322 R/Wdata i/o TransferFunction 301 R/W WhitePoint 318 R/W XPosition 286 R/W XResolution 282 R/W YCbCrCoefficients 529 R/Wused by TIFFRGBAImage support YCbCrPositioning 531 R/Wtile/strip size calulcations YCbCrSubsampling 530 R/W YPosition 286 R/W YResolution 283 R/Wused by Group 3 codec
In addition to the normal TIFF tags the library supports a collection of tags whose values lie in a range outside the valid range of TIFF tags. These tags are termed pseud-tags and are used to control various codec-specific functions within the library. The table below summarizes the defined pseudo-tags.
Tag Name Codec R/WLibrary Use/Notes
TIFFTAG_FAXMODE G3 R/Wgeneral codec operation TIFFTAG_FAXFILLFUNC G3/G4 R/Wbitmap fill function TIFFTAG_JPEGQUALITY JPEG R/Wcompression quality control TIFFTAG_JPEGCOLORMODE JPEG R/Wcontrol colorspace conversions TIFFTAG_JPEGTABLESMODE JPEGR/Wcontrol contents of JPEGTables tag TIFFTAG_ZIPQUALITY Deflate R/Wcompression quality level TIFFTAG_PIXARLOGDATAFMT PixarLogR/Wuser data format TIFFTAG_PIXARLOGQUALITY PixarLogR/Wcompression quality level TIFFTAG_SGILOGDATAFMT SGILog R/Wuser data format
TIFFTAG_FAXMODE Control the operation of the Group 3 codec. Possible values (independent bits that can be combined by oring them together) are: FAXMODE_CLASSIC (enable old-style format in which the RTC is written at the end of the last strip), FAXMODE_NORTC (opposite of FAXMODE_CLASSIC; also called FAXMODE_CLASSF), FAXMODE_NOEOL (do not write EOL codes at the start of each row of data), FAXMODE_BYTEALIGN (align each encoded row to an 8-bit boundary), FAXMODE_WORDALIGN (align each encoded row to an 16-bit boundary), The default value is dependent on the compression scheme; this pseudo-tag is used by the various G3 and G4 codecs to share code. TIFFTAG_FAXFILLFUNC Control the function used to convert arrays of black and white runs to packed bit arrays. This hook can be used to image decoded scanlines in multi-bit depth rasters (e.g. for display in colormap mode) or for other purposes. The default value is a pointer to a builtin function that images packed bilevel data. TIFFTAG_IPTCNEWSPHOTO Tag contaings image metadata per the IPTC newsphoto spec: Headline, captioning, credit, etc... Used by most wire services. TIFFTAG_PHOTOSHOP Tag contains Photoshop captioning information and metadata. Photoshop uses in parallel and redundantly alongside IPTCNEWSPHOTO information. TIFFTAG_JPEGQUALITY Control the compression quality level used in the baseline algorithm. Note that quality levels are in the range 0-100 with a default value of 75. TIFFTAG_JPEGCOLORMODE Control whether or not conversion is done between RGB and YCbCr colorspaces. Possible values are: JPEGCOLORMODE_RAW (do not convert), and JPEGCOLORMODE_RGB (convert to/from RGB) The default value is JPEGCOLORMODE_RAW. TIFFTAG_JPEGTABLESMODE Control the information written in the JPEGTables tag. Possible values (independent bits that can be combined by oring them together) are: JPEGTABLESMODE_QUANT (include quantization tables), and JPEGTABLESMODE_HUFF (include Huffman encoding tables). The default value is JPEGTABLESMODE_QUANT|JPEGTABLESMODE_HUFF. TIFFTAG_ZIPQUALITY Control the compression technique used by the Deflate codec. Quality levels are in the range 1-9 with larger numbers yielding better compression at the cost of more computation. The default quality level is 6 which yields a good time-space tradeoff. TIFFTAG_PIXARLOGDATAFMT Control the format of user data passed in to the PixarLog codec when encoding and passed out from when decoding. Possible values are: PIXARLOGDATAFMT_8BIT for 8-bit unsigned pixels, PIXARLOGDATAFMT_8BITABGR for 8-bit unsigned ABGR-ordered pixels, PIXARLOGDATAFMT_11BITLOG for 11-bit log-encoded raw data, PIXARLOGDATAFMT_12BITPICIO for 12-bit PICIO-compatible data, PIXARLOGDATAFMT_16BIT for 16-bit signed samples, and PIXARLOGDATAFMT_FLOAT for 32-bit IEEE floating point samples. TIFFTAG_PIXARLOGQUALITY Control the compression technique used by the PixarLog codec. This value is treated identically to TIFFTAG_ZIPQUALITY; see the above description. TIFFTAG_SGILOGDATAFMT Control the format of client data passed in to the SGILog codec when encoding and passed out from when decoding. Possible values are: SGILOGDATAFMT_FLTXYZ for converting between LogLuv and 32-bit IEEE floating valued XYZ pixels, SGILOGDATAFMT_16BITLUV for 16-bit encoded Luv pixels, SGILOGDATAFMT_32BITRAW and SGILOGDATAFMT_24BITRAW for no conversion of data, SGILOGDATAFMT_8BITRGB for returning 8-bit RGB data (valid only when decoding LogLuv-encoded data), SGILOGDATAFMT_FLTY for converting between LogL and 32-bit IEEE floating valued Y pixels, SGILOGDATAFMT_16BITL for 16-bit encoded L pixels, and SGILOGDATAFMT_8BITGRY for returning 8-bit greyscale data (valid only when decoding LogL-encoded data).
All error messages are directed through the TIFFError routine. By default messages are directed to stderr in the form: module: message\n. Warning messages are likewise directed through the TIFFWarning routine.
fax2tiff(1), gif2tiff(1), pal2rgb(1), ppm2tiff(1), rgb2ycbcr(1), ras2tiff(1), raw2tiff(1), sgi2tiff(1), tiff2bw(1), tiffdither(1), tiffdump(1), tiffcp(1), tiffcmp(1), tiffgt(1), tiffinfo(1), tiffmedian(1), tiffsplit(1), tiffsv(1),
Tag Image File Format Specification Revision 6.0, an Aldus Technical Memorandum.
The Spirit of TIFF Class F, an appendix to the TIFF 5.0 specification prepared by Cygnet Technologies.
The library does not support multi-sample images where some samples have different bits/sample.
The library does not support random access to compressed data that is organized with more than one row per tile or strip. The library discards unknown tags. The library should do more validity checking of a directorys contents.
|INTRO (3T)||August 21, 1997|