libtiff
INTRO(3T) INTRO(3T)
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 com-
pression 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 pre-
sumed.
LIST OF ROUTINES
The following routines are part of the library. Consult specific man-
ual 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
TIFFCheckTile tile.3t very x,y,z,sample is within image
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
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
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
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
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 size.3t return size of a 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
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
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
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-spe-
cific tags and the library does not recognize them except when the Com-
pression 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
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 summa-
rizes 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 (oppo-
site of FAXMODE_CLASSIC; also called FAXMODE_CLASSF), FAX-
MODE_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 compres-
sion 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: Head-
line, captioning, credit, etc... Used by most wire services.
TIFFTAG_PHOTOSHOP
Tag contains Photoshop captioning information and metadata. Pho-
toshop uses in parallel and redundantly alongside IPTCNEWSPHOTO
information.
TIFFTAG_JPEGQUALITY
Control the compression quality level used in the baseline algo-
rithm. 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|JPEGTA-
BLESMODE_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 val-
ues are: PIXARLOGDATAFMT_8BIT for 8-bit unsigned pixels, PIXAR-
LOGDATAFMT_8BITABGR for 8-bit unsigned ABGR-ordered pixels,
PIXARLOGDATAFMT_11BITLOG for 11-bit log-encoded raw data, PIXAR-
LOGDATAFMT_12BITPICIO for 12-bit PICIO-compatible data, PIXAR-
LOGDATAFMT_16BIT for 16-bit signed samples, and PIXARLOG-
DATAFMT_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 val-
ues 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, SGILOG-
DATAFMT_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 SGILOG-
DATAFMT_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), sgi2tiff(1), tiff2bw(1), tiffdither(1), tiffdump(1),
tiffcp(1), tiffcmp(1), tiffgt(1), tiffinfo(1), tiffmedian(1), tiffs-
plit(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 dis-
cards unknown tags. The library should do more validity checking of a
directory's contents.
August 21, 1997 INTRO(3T)
