INTRO(3T) INTRO(3T)
NAME
libtiff - introduction to libtiff, a library for reading and writing TIFF files
SYNOPSIS
#include
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 Fac-
simile compression (3), CCITT Group 4 Facsimile compression (4), Lempel-Ziv & Welch com-
pression (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 Sig-
nificant 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 MaxSam-
pleValue 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 type-
defs 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 quanti-
ties 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/Wused 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 TAGS
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/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/Wcompression quality level
TIFFTAG_PIXARLOGDATAFMT PixarLog R/Wuser data format
TIFFTAG_PIXARLOGQUALITY PixarLog R/Wcompression 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 par-
allel 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. Pos-
sible values are: JPEGCOLORMODE_RAW (do not convert), and JPEGCOLORMODE_RGB (con-
vert to/from RGB) The default value is JPEGCOLORMODE_RAW.
TIFFTAG_JPEGTABLESMODE
Control the information written in the JPEGTables tag. Possible values (indepen-
dent 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 trade-
off.
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_12BITPI-
CIO for 12-bit PICIO-compatible data, PIXARLOGDATAFMT_16BIT for 16-bit signed sam-
ples, 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 con-
verting between LogLuv and 32-bit IEEE floating valued XYZ pixels, SGILOG-
DATAFMT_16BITLUV for 16-bit encoded Luv pixels, SGILOGDATAFMT_32BITRAW and SGILOG-
DATAFMT_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, SGILOG-
DATAFMT_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.
August 21, 1997 INTRO(3T)
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