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; on most systems doing ``man function-name''
will work.
Name Description
TIFFCheckpointDirectory writes 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/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
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/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.
Libtiff library home page:
http://www.remotesensing.org/libtiff/
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.