INTRO(3T)INTRO(3T)NAMElibtiff - introduction to libtiff, a library for reading
and writing TIFF files
SYNOPSIS
#include <tiffio.h>
cc file.c -ltiff
DESCRIPTIONlibtiff 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 suit
able for archiving multi-color and monochromatic image
data.
The library supports several compression algorithms, as
indicated by the Compression field, including: no compres
sion (1), CCITT 1D Huffman compression (2), CCITT Group 3
Facsimile compression (3), CCITT Group 4 Facsimile com
pression (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 com
pression algorithm (32766) (decompression only), an exper
imental 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 lit
tle- or big-endian byte order-byte swapping is automati
cally 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 sup
port files in which the BitsPerSample, Compression, Min_
SampleValue, or MaxSampleValue fields are defined differ
ently on a per-sample basis (in Rev. 6.0 the Compression
tag is not defined on a per-sample basis, so this is imma
terial).
DATA TYPES
The library makes extensive use of C typedefs to promote
portability. Two sets of typedefs are used, one for com
munication with clients of the library and one for inter
nal 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 SamplesPer_
Pixel 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 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
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 consid
ered codec-specific tags and the library does not recog
nize them except when the Compression tag has been previ
ously 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 func
tions 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. Possi
ble values (independent bits that can be combined
by or'ing them together) are: FAXMODE_CLASSIC
(enable old-style format in which the RTC is writ
ten at the end of the last strip), FAXMODE_NORTC
(opposite of FAXMODE_CLASSIC; also called FAX
MODE_CLASSF), FAXMODE_NOEOL (do not write EOL codes
at the start of each row of data), FAX
MODE_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 col
ormap 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 redun
dantly 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 JPEGCOLOR
MODE_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: JPEGTA
BLESMODE_QUANT (include quantization tables), and
JPEGTABLESMODE_HUFF (include Huffman encoding
tables). The default value is JPEGTA
BLESMODE_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: PIXARLOG
DATAFMT_8BIT for 8-bit unsigned pixels, PIXARLOG
DATAFMT_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 PIXARLOG
DATAFMT_FLOAT for 32-bit IEEE floating point sam
ples.
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: SGILOG
DATAFMT_FLTXYZ for converting between LogLuv and
32-bit IEEE floating valued XYZ pixels, SGILOG
DATAFMT_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 float
ing 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 rou
tine. By default messages are directed to stderr in the
form: module: message\n. Warning messages are likewise
directed through the TIFFWarning routine.
SEE ALSOfax2tiff(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), 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 con
tents.
August 21, 1997 INTRO(3T)
