Table of Contents

Name

libtiff - introduction to libtiff, a library for reading and writing TIFF files

Synopsis

#include <tiffio.h>
cc file.c -ltiff

Description

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), NeXT’s 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).

Data Types

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.

List of Routines

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 Page    Description

TIFFCheckpointDirectory writedir.3t    writes 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.3t    return tag value in current directory
TIFFGetMode    query.3t    return open file mode
TIFFGetVersion    query.3t    return library version string
TIFFIsCODECConfigured    codec.3t    check, 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 tag’s value in the current directory
TIFFSetWarningHandler    error.3t    set 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.3t    return tag value in current directory
TIFFVSetField    setfield.3t    set a tag’s 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.3t    compress 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

Tag Usage

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/W    Library Use/Notes


Artist    315    R/W
BadFaxLines    326    R/W
BitsPerSample    258    R/W    lots
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/W    choosing codec
ConsecutiveBadFaxLines    328    R/W
Copyright       33432   R/W
DataType    32996    R    obsoleted by SampleFormat tag
DateTime    306    R/W
DocumentName    269    R/W
DotRange    336    R/W
ExtraSamples    338    R/W    lots
FaxRecvParams    34908    R/W
FaxSubAddress    34909    R/W
FaxRecvTime    34910    R/W
FillOrder    266    R/W    control 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/W    used by Group 3 codec
Group4Options    293    R/W
HostComputer    316    R/W
ImageDepth    32997    R/W    tile/strip calculations
ImageDescription     270    R/W
ImageLength    257    R/W    lots
ImageWidth    256    R/W    lots
InkNames    333    R/W
InkSet    332    R/W
JPEGTables    347    R/W    used by JPEG codec
Make    271    R/W
Matteing    32995    R    obsoleted by ExtraSamples tag
MaxSampleValue    281    R/W
MinSampleValue    280    R/W
Model    272    R/W
NewSubFileType    254    R/W    called SubFileType in spec
NumberOfInks    334    R/W
Orientation    274    R/W
PageName    285    R/W
PageNumber    297    R/W
PhotometricInterpretation    262    R/W    used by Group 3 and JPEG codecs
PlanarConfiguration    284    R/W    data i/o
Predictor    317    R/W    used by LZW and Deflate codecs
PrimaryChromacities    319    R/W
ReferenceBlackWhite    532    R/W
ResolutionUnit    296    R/W    used by Group 3 codec
RowsPerStrip    278    R/W    data i/o
SampleFormat    339    R/W
SamplesPerPixel    277    R/W    lots
SMinSampleValue    340    R/W
SMaxSampleValue    341    R/W
Software    305    R/W
StoNits    37439    R/W
StripByteCounts    279    R/W    data i/o
StripOffsets    273    R/W    data i/o
SubFileType    255    R/W    called OSubFileType in spec
TargetPrinter    337    R/W
Thresholding    263    R/W    
TileByteCounts    324    R/W    data i/o
TileDepth    32998    R/W    tile/strip calculations
TileLength    323    R/W    data i/o
TileOffsets    324    R/W    data i/o
TileWidth    322    R/W    data i/o
TransferFunction    301    R/W
WhitePoint    318    R/W
XPosition    286    R/W
XResolution    282    R/W
YCbCrCoefficients    529    R/W    used by TIFFRGBAImage support
YCbCrPositioning    531    R/W    tile/strip size calulcations
YCbCrSubsampling    530    R/W
YPosition    286    R/W
YResolution    283    R/W    used by Group 3 codec
Pseudo TagsIn 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/W    Library Use/Notes


TIFFTAG_FAXMODE    G3    R/W    general codec operation
TIFFTAG_FAXFILLFUNC    G3/G4    R/W    bitmap fill function
TIFFTAG_JPEGQUALITY    JPEG    R/W    compression quality control
TIFFTAG_JPEGCOLORMODE    JPEG    R/W    control colorspace conversions
TIFFTAG_JPEGTABLESMODE    JPEG    R/W    control contents of JPEGTables tag
TIFFTAG_ZIPQUALITY    Deflate    R/W    compression quality level
TIFFTAG_PIXARLOGDATAFMT    PixarLog    R/W    user data format
TIFFTAG_PIXARLOGQUALITY    PixarLog    R/W    compression quality level
TIFFTAG_SGILOGDATAFMT    SGILog    R/W    user data format
TIFFTAG_FAXMODE
Control the operation of the Group 3 codec. Possible values (independent bits that can be combined by or’ing 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 or’ing 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).

Diagnostics

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.

See Also

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.

Bugs

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 directory’s contents.


Table of Contents