Tribblix: manual page: libtiff.3tiff

INTRO(3TIFF) INTRO(3TIFF)

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_t; 16-bit unsigned integer
typedef unsigned <thing> uint32_t; 32-bit unsigned integer
typedef unsigned int ttag_t; directory tag
typedef uint16_t tdir_t; directory index
typedef uint16_t tsample_t; sample number
typedef uint32_t tstrip_t; strip number
typedef uint32_t ttile_t; tile number
typedef int32_t tsize_t; i/o size in bytes
typedef void* tdata_t; image data ref
typedef void* thandle_t; client data handle
typedef int32_t 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_t 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; on most systems doing
``man function-name'' will work.

Name Description
TIFFCheckpointDirectorywrites the current state of the directory
TIFFCheckTile very x,y,z,sample is within image
TIFFCIELabToRGBInit initialize CIE L*a*b* 1976 to RGB conversion state
TIFFCIELabToXYZ perform CIE L*a*b* 1976 to CIE XYZ conversion
TIFFClientOpen open a file for reading or writing
TIFFClose close an open file
TIFFComputeStrip return strip containing y,sample
TIFFComputeTile return tile containing x,y,z,sample
TIFFCurrentDirectory return index of current directory
TIFFCurrentRow return index of current scanline
TIFFCurrentStrip return index of current strip
TIFFCurrentTile return index of current tile
TIFFDataWidth return the size of TIFF data types
TIFFError library error handler
TIFFFdOpen open a file for reading or writing
TIFFFieldDataType get data type from field information
TIFFFieldName get field name from field information
TIFFFieldPassCount get whether to pass a value count to Get/SetField
TIFFFieldReadCount get number of values to be read from field
TIFFFieldTag get tag value from field information
TIFFFieldWithName get field information given field name
TIFFFieldWithTag get field information given tag
TIFFFieldWriteCount get number of values to be written to field
TIFFFileName return name of open file
TIFFFileno return open file descriptor
TIFFFindCODEC find standard codec for the specific scheme
TIFFFindField get field information given tag and data type
TIFFFlush flush all pending writes
TIFFFlushData flush pending data writes
TIFFGetBitRevTable return bit reversal table
TIFFGetField return tag value in current directory
TIFFGetFieldDefaulted return tag value in current directory
TIFFGetMode return open file mode
TIFFGetVersion return library version string
TIFFIsCODECConfigured check, whether we have working codec
TIFFIsMSB2LSB return true if image data is being returned
with bit 0 as the most significant bit
TIFFIsTiled return true if image data is tiled
TIFFIsByteSwapped return true if image data is byte-swapped
TIFFNumberOfStrips return number of strips in an image
TIFFNumberOfTiles return number of tiles in an image
TIFFOpen open a file for reading or writing
TIFFPrintDirectory print description of the current directory
TIFFReadBufferSetup specify i/o buffer for reading
TIFFReadDirectory read the next directory
TIFFReadEncodedStrip read and decode a strip of data
TIFFReadEncodedTile read and decode a tile of data
TIFFReadRawStrip read a raw strip of data
TIFFReadRawTile read a raw tile of data
TIFFReadRGBAImage read an image into a fixed format raster
TIFFReadScanline read and decode a row of data
TIFFReadTile read and decode a tile of data
TIFFRegisterCODEC override standard codec for the specific scheme
TIFFReverseBits reverse bits in an array of bytes
TIFFRGBAImageBegin setup decoder state for TIFFRGBAImageGet
TIFFRGBAImageEnd release TIFFRGBAImage decoder state
TIFFRGBAImageGet read and decode an image
TIFFRGBAImageOK is image readable by TIFFRGBAImageGet
TIFFScanlineSize return size of a scanline
TIFFSetDirectory set the current directory
TIFFSetSubDirectory set the current directory
TIFFSetErrorHandler set error handler function
TIFFSetField set a tag's value in the current directory
TIFFSetWarningHandler set warning handler function
TIFFStripSize returns size of a strip
TIFFRawStripSize returns the number of bytes in a raw strip
TIFFSwabShort swap bytes of short
TIFFSwabLong swap bytes of long
TIFFSwabArrayOfShort swap bytes of an array of shorts
TIFFSwabArrayOfLong swap bytes of an array of longs
TIFFTileRowSize return size of a row in a tile
TIFFTileSize return size of a tile
TIFFUnRegisterCODEC unregisters the codec
TIFFVGetField return tag value in current directory
TIFFVGetFieldDefaulted return tag value in current directory
TIFFVSetField set a tag's value in the current directory
TIFFVStripSize returns the number of bytes in a strip
TIFFWarning library warning handler
TIFFWriteDirectory write the current directory
TIFFWriteEncodedStrip compress and write a strip of data
TIFFWriteEncodedTile compress and write a tile of data
TIFFWriteRawStrip write a raw strip of data
TIFFWriteRawTile write a raw tile of data
TIFFWriteScanline write a scanline of data
TIFFWriteTile compress and write a tile of data
TIFFXYZToRGB perform CIE XYZ to RGB conversion
TIFFYCbCrToRGBInit initialize YCbCr to RGB conversion state
TIFFYCbCrtoRGB perform YCbCr to RGB conversion

Auxiliary functions:
_TIFFfree free memory buffer
_TIFFmalloc dynamically allocate memory buffer
_TIFFmemcmp compare contents of the memory buffers
_TIFFmemcpy copy contents of the one buffer to another
_TIFFmemset fill memory buffer with a constant byte
_TIFFrealloc dynamically reallocate memory buffer

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/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 calculations
YCbCrSubsampling 530 R/W
YPosition 286 R/W
YResolution 283 R/Wused 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 pseudo-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 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 contains 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.

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.

libtiff November 2, 2005 INTRO(3TIFF)