src/tiff/man/TIFFRGBAImage.3tiff

.\" $Id: TIFFRGBAImage.3tiff,v 1.2 2005/11/02 11:07:18 dron Exp $
.\"
.\" Copyright (c) 1991-1997 Sam Leffler
.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
.\"
.\" Permission to use, copy, modify, distribute, and sell this software and
.\" its documentation for any purpose is hereby granted without fee, provided
.\" that (i) the above copyright notices and this permission notice appear in
.\" all copies of the software and related documentation, and (ii) the names of
.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
.\" publicity relating to the software without the specific, prior written
.\" permission of Sam Leffler and Silicon Graphics.
.\"
.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
.\"
.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
.\" OF THIS SOFTWARE.
.\"
.if n .po 0
.TH TIFFRGBAImage 3TIFF "October 29, 2004" "libtiff"
.SH NAME
TIFFRGBAImageOK, TIFFRGBAImageBegin, TIFFRGBAImageGet, TIFFRGBAImageEnd
\- read and decode an image into a raster
.SH SYNOPSIS
.B "#include <tiffio.h>"
.sp
.B "typedef unsigned char TIFFRGBValue;"
.B "typedef struct _TIFFRGBAImage TIFFRGBAImage;"
.sp
.BI "int TIFFRGBAImageOK(TIFF *" tif ", char " emsg[1024] ")"
.br
.BI "int TIFFRGBAImageBegin(TIFFRGBAImage *" img ", TIFF* " tif ", int " stopOnError ", char " emsg[1024] ")"
.br
.BI "int TIFFRGBAImageGet(TIFFRGBAImage *" img ", uint32* " raster ", uint32 " width " , uint32 " height ")"
.br
.BI "void TIFFRGBAImageEnd(TIFFRGBAImage *" img ")"
.br
.SH DESCRIPTION
The routines described here provide a high-level interface
through which
.SM TIFF
images may be read into memory.
Images may be strip- or tile-based and have a variety of different
characteristics: bits/sample, samples/pixel, photometric, etc.
Decoding state is encapsulated in a
.I TIFFRGBAImage
structure making it possible to capture state for multiple images
and quickly switch between them.
The target raster format can be customized to a particular application's
needs by installing custom routines that manipulate image data
according to application requirements.
.PP
The default usage for these routines is: check if an image can
be processed using
.IR TIFFRGBAImageOK ,
construct a decoder state block using
.IR TIFFRGBAImageBegin ,
read and decode an image into a target raster using
.IR TIFFRGBAImageGet ,
and then
release resources using
.IR TIFFRGBAImageEnd .
.I TIFFRGBAImageGet
can be called multiple times to decode an image using different
state parameters.
If multiple images are to be displayed and there is not enough
space for each of the decoded rasters, multiple state blocks can
be managed and then calls can be made to
.I TIFFRGBAImageGet
as needed to display an image.
.PP
The generated raster is assumed to be an array of
.I width
times
.I height
32-bit entries, where
.I width
must be less than or equal to the width of the image (\c
.I height
may be any non-zero size).
If the raster dimensions are smaller than the image, the image data
is cropped to the raster bounds.
If the raster height is greater than that of the image, then the
image data are placed in the lower part of the raster.
(Note that the raster is assume to be organized such that the pixel
at location (\fIx\fP,\fIy\fP) is \fIraster\fP[\fIy\fP*\fIwidth\fP+\fIx\fP];
with the raster origin in the
.B lower-left
hand corner.)
.PP
Raster pixels are 8-bit packed red, green, blue, alpha samples.
The macros
.IR TIFFGetR ,
.IR TIFFGetG ,
.IR TIFFGetB ,
and
.I TIFFGetA
should be used to access individual samples.
Images without Associated Alpha matting information have a constant
Alpha of 1.0 (255).
.PP
.I TIFFRGBAImageGet
converts non-8-bit images by scaling sample values.
Palette, grayscale, bilevel,
.SM CMYK\c
, and YCbCr images are converted to
.SM RGB
transparently.
Raster pixels are returned uncorrected by any colorimetry information
present in the directory.
.PP
The parameter
.I stopOnError
specifies how to act if an error is encountered while reading
the image.
If
.I stopOnError
is non-zero, then an error will terminate the operation; otherwise
.I TIFFRGBAImageGet
will continue processing data until all the possible data in the
image have been requested.
.SH "ALTERNATE RASTER FORMATS"
To use the core support for reading and processing
.SM TIFF
images, but write the resulting raster data in a different format
one need only override the ``\fIput methods\fP'' used to store raster data.
These methods are are defined in the
.I TIFFRGBAImage
structure and initially setup by
.I TIFFRGBAImageBegin
to point to routines that pack raster data in the default
.SM ABGR
pixel format.
Two different routines are used according to the physical organization
of the image data in the file:
.IR PlanarConfiguration =1
(packed samples),
and
.IR PlanarConfiguration =2
(separated samples).
Note that this mechanism can be used to transform the data before
storing it in the raster.
For example one can convert data
to colormap indices for display on a colormap display.
.SH "SIMULTANEOUS RASTER STORE AND DISPLAY"
It is simple to display an image as it is being read into memory
by overriding the put methods as described above for supporting
alternate raster formats.
Simply keep a reference to the default put methods setup by
.I TIFFRGBAImageBegin
and then invoke them before or after each display operation.
For example, the
.IR tiffgt (1)
utility uses the following put method to update the display as
the raster is being filled:
.sp
.nf
.ft C
static void
putContigAndDraw(TIFFRGBAImage* img, uint32* raster,
    uint32 x, uint32 y, uint32 w, uint32 h,
    int32 fromskew, int32 toskew,
    unsigned char* cp)
{
    (*putContig)(img, raster, x, y, w, h, fromskew, toskew, cp);
    if (x+w == width) {
	w = width;
	if (img->orientation == ORIENTATION_TOPLEFT)
	    lrectwrite(0, y-(h-1), w-1, y, raster-x-(h-1)*w);
	else
	    lrectwrite(0, y, w-1, y+h-1, raster);
    }
}
.ft R
.fi
.sp
(the original routine provided by the library is saved in the
variable
.IR putContig .)
.SH "SUPPORTING ADDITIONAL TIFF FORMATS"
The
.I TIFFRGBAImage
routines support the most commonly encountered flavors of
.SM TIFF.
It is possible to extend this support by overriding the ``\fIget method\fP''
invoked by
.I TIFFRGBAImageGet
to read
.SM TIFF
image data.
Details of doing this are a bit involved, it is best to make a copy
of an existing get method and modify it to suit the needs of an
application.
.SH NOTES
Samples must be either 1, 2, 4, 8, or 16 bits.
Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
.I SamplesPerPixel
minus
.IR ExtraSamples ).
.PP
Palette image colormaps that appear to be incorrectly written
as 8-bit values are automatically scaled to 16-bits.
.SH "RETURN VALUES"
All routines return
1 if the operation was successful.
Otherwise, 0 is returned if an error was encountered and
.I stopOnError
is zero.
.SH DIAGNOSTICS
All error messages are directed to the
.IR TIFFError (3TIFF)
routine.
.PP
.BR "Sorry, can not handle %d-bit pictures" .
The image had
.I BitsPerSample
other than 1, 2, 4, 8, or 16.
.PP
.BR "Sorry, can not handle %d-channel images" .
The image had
.I SamplesPerPixel
other than 1, 3, or 4.
.PP
\fBMissing needed "PhotometricInterpretation" tag\fP.
The image did not have a tag that describes how to display
the data.
.PP
\fBNo "PhotometricInterpretation" tag, assuming RGB\fP.
The image was missing a tag that describes how to display it,
but because it has 3 or 4 samples/pixel, it is assumed to be
.SM RGB.
.PP
\fBNo "PhotometricInterpretation" tag, assuming min-is-black\fP.
The image was missing a tag that describes how to display it,
but because it has 1 sample/pixel, it is assumed to be a grayscale
or bilevel image.
.PP
.BR "No space for photometric conversion table" .
There was insufficient memory for a table used to convert
image samples to 8-bit
.SM RGB.
.PP
\fBMissing required "Colormap" tag\fP.
A Palette image did not have a required
.I Colormap
tag.
.PP
.BR "No space for tile buffer" .
There was insufficient memory to allocate an i/o buffer.
.PP
.BR "No space for strip buffer" .
There was insufficient memory to allocate an i/o buffer.
.PP
.BR "Can not handle format" .
The image has a format (combination of
.IR BitsPerSample ,
.IR SamplesPerPixel ,
and
.IR PhotometricInterpretation )
that can not be handled.
.PP
.BR "No space for B&W mapping table" .
There was insufficient memory to allocate a table used to map
grayscale data to
.SM RGB.
.PP
.BR "No space for Palette mapping table" .
There was insufficient memory to allocate a table used to map
data to 8-bit
.SM RGB.
.SH "SEE ALSO"
.BR TIFFOpen (3TIFF),
.BR TIFFReadRGBAImage (3TIFF),
.BR TIFFReadRGBAImageOriented (3TIFF),
.BR TIFFReadRGBAStrip (3TIFF),
.BR TIFFReadRGBATile (3TIFF),
.BR libtiff (3TIFF)
.PP
Libtiff library home page:
.BR http://www.remotesensing.org/libtiff/
Commit	Line	Data
	1	.\" $Id: TIFFRGBAImage.3tiff,v 1.2 2005/11/02 11:07:18 dron Exp $
	2	.\"
	3	.\" Copyright (c) 1991-1997 Sam Leffler
	4	.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
	5	.\"
	6	.\" Permission to use, copy, modify, distribute, and sell this software and
	7	.\" its documentation for any purpose is hereby granted without fee, provided
	8	.\" that (i) the above copyright notices and this permission notice appear in
	9	.\" all copies of the software and related documentation, and (ii) the names of
	10	.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
	11	.\" publicity relating to the software without the specific, prior written
	12	.\" permission of Sam Leffler and Silicon Graphics.
	13	.\"
	14	.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
	15	.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
	16	.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	17	.\"
	18	.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
	19	.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
	20	.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	21	.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
	22	.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	23	.\" OF THIS SOFTWARE.
	24	.\"
	25	.if n .po 0
	26	.TH TIFFRGBAImage 3TIFF "October 29, 2004" "libtiff"
	27	.SH NAME
	28	TIFFRGBAImageOK, TIFFRGBAImageBegin, TIFFRGBAImageGet, TIFFRGBAImageEnd
	29	\- read and decode an image into a raster
	30	.SH SYNOPSIS
	31	.B "#include <tiffio.h>"
	32	.sp
	33	.B "typedef unsigned char TIFFRGBValue;"
	34	.B "typedef struct _TIFFRGBAImage TIFFRGBAImage;"
	35	.sp
	36	.BI "int TIFFRGBAImageOK(TIFF *" tif ", char " emsg[1024] ")"
	37	.br
	38	.BI "int TIFFRGBAImageBegin(TIFFRGBAImage " img ", TIFF " tif ", int " stopOnError ", char " emsg[1024] ")"
	39	.br
	40	.BI "int TIFFRGBAImageGet(TIFFRGBAImage " img ", uint32 " raster ", uint32 " width " , uint32 " height ")"
	41	.br
	42	.BI "void TIFFRGBAImageEnd(TIFFRGBAImage *" img ")"
	43	.br
	44	.SH DESCRIPTION
	45	The routines described here provide a high-level interface
	46	through which
	47	.SM TIFF
	48	images may be read into memory.
	49	Images may be strip- or tile-based and have a variety of different
	50	characteristics: bits/sample, samples/pixel, photometric, etc.
	51	Decoding state is encapsulated in a
	52	.I TIFFRGBAImage
	53	structure making it possible to capture state for multiple images
	54	and quickly switch between them.
	55	The target raster format can be customized to a particular application's
	56	needs by installing custom routines that manipulate image data
	57	according to application requirements.
	58	.PP
	59	The default usage for these routines is: check if an image can
	60	be processed using
	61	.IR TIFFRGBAImageOK ,
	62	construct a decoder state block using
	63	.IR TIFFRGBAImageBegin ,
	64	read and decode an image into a target raster using
	65	.IR TIFFRGBAImageGet ,
	66	and then
	67	release resources using
	68	.IR TIFFRGBAImageEnd .
	69	.I TIFFRGBAImageGet
	70	can be called multiple times to decode an image using different
	71	state parameters.
	72	If multiple images are to be displayed and there is not enough
	73	space for each of the decoded rasters, multiple state blocks can
	74	be managed and then calls can be made to
	75	.I TIFFRGBAImageGet
	76	as needed to display an image.
	77	.PP
	78	The generated raster is assumed to be an array of
	79	.I width
	80	times
	81	.I height
	82	32-bit entries, where
	83	.I width
	84	must be less than or equal to the width of the image (\c
	85	.I height
	86	may be any non-zero size).
	87	If the raster dimensions are smaller than the image, the image data
	88	is cropped to the raster bounds.
	89	If the raster height is greater than that of the image, then the
	90	image data are placed in the lower part of the raster.
	91	(Note that the raster is assume to be organized such that the pixel
	92	at location (\fIx\fP,\fIy\fP) is \fIraster\fP[\fIy\fP*\fIwidth\fP+\fIx\fP];
	93	with the raster origin in the
	94	.B lower-left
	95	hand corner.)
	96	.PP
	97	Raster pixels are 8-bit packed red, green, blue, alpha samples.
	98	The macros
	99	.IR TIFFGetR ,
	100	.IR TIFFGetG ,
	101	.IR TIFFGetB ,
	102	and
	103	.I TIFFGetA
	104	should be used to access individual samples.
	105	Images without Associated Alpha matting information have a constant
	106	Alpha of 1.0 (255).
	107	.PP
	108	.I TIFFRGBAImageGet
	109	converts non-8-bit images by scaling sample values.
	110	Palette, grayscale, bilevel,
	111	.SM CMYK\c
	112	, and YCbCr images are converted to
	113	.SM RGB
	114	transparently.
	115	Raster pixels are returned uncorrected by any colorimetry information
	116	present in the directory.
	117	.PP
	118	The parameter
	119	.I stopOnError
	120	specifies how to act if an error is encountered while reading
	121	the image.
	122	If
	123	.I stopOnError
	124	is non-zero, then an error will terminate the operation; otherwise
	125	.I TIFFRGBAImageGet
	126	will continue processing data until all the possible data in the
	127	image have been requested.
	128	.SH "ALTERNATE RASTER FORMATS"
	129	To use the core support for reading and processing
	130	.SM TIFF
	131	images, but write the resulting raster data in a different format
	132	one need only override the ``\fIput methods\fP'' used to store raster data.
	133	These methods are are defined in the
	134	.I TIFFRGBAImage
	135	structure and initially setup by
	136	.I TIFFRGBAImageBegin
	137	to point to routines that pack raster data in the default
	138	.SM ABGR
	139	pixel format.
	140	Two different routines are used according to the physical organization
	141	of the image data in the file:
	142	.IR PlanarConfiguration =1
	143	(packed samples),
	144	and
	145	.IR PlanarConfiguration =2
	146	(separated samples).
	147	Note that this mechanism can be used to transform the data before
	148	storing it in the raster.
	149	For example one can convert data
	150	to colormap indices for display on a colormap display.
	151	.SH "SIMULTANEOUS RASTER STORE AND DISPLAY"
	152	It is simple to display an image as it is being read into memory
	153	by overriding the put methods as described above for supporting
	154	alternate raster formats.
	155	Simply keep a reference to the default put methods setup by
	156	.I TIFFRGBAImageBegin
	157	and then invoke them before or after each display operation.
	158	For example, the
	159	.IR tiffgt (1)
	160	utility uses the following put method to update the display as
	161	the raster is being filled:
	162	.sp
	163	.nf
	164	.ft C
	165	static void
	166	putContigAndDraw(TIFFRGBAImage* img, uint32* raster,
	167	uint32 x, uint32 y, uint32 w, uint32 h,
	168	int32 fromskew, int32 toskew,
	169	unsigned char* cp)
	170	{
	171	(*putContig)(img, raster, x, y, w, h, fromskew, toskew, cp);
	172	if (x+w == width) {
	173	w = width;
	174	if (img->orientation == ORIENTATION_TOPLEFT)
	175	lrectwrite(0, y-(h-1), w-1, y, raster-x-(h-1)*w);
	176	else
	177	lrectwrite(0, y, w-1, y+h-1, raster);
	178	}
	179	}
	180	.ft R
	181	.fi
	182	.sp
	183	(the original routine provided by the library is saved in the
	184	variable
	185	.IR putContig .)
	186	.SH "SUPPORTING ADDITIONAL TIFF FORMATS"
	187	The
	188	.I TIFFRGBAImage
	189	routines support the most commonly encountered flavors of
	190	.SM TIFF.
	191	It is possible to extend this support by overriding the ``\fIget method\fP''
	192	invoked by
	193	.I TIFFRGBAImageGet
	194	to read
	195	.SM TIFF
	196	image data.
	197	Details of doing this are a bit involved, it is best to make a copy
	198	of an existing get method and modify it to suit the needs of an
	199	application.
	200	.SH NOTES
	201	Samples must be either 1, 2, 4, 8, or 16 bits.
	202	Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
	203	.I SamplesPerPixel
	204	minus
	205	.IR ExtraSamples ).
	206	.PP
	207	Palette image colormaps that appear to be incorrectly written
	208	as 8-bit values are automatically scaled to 16-bits.
	209	.SH "RETURN VALUES"
	210	All routines return
	211	1 if the operation was successful.
	212	Otherwise, 0 is returned if an error was encountered and
	213	.I stopOnError
	214	is zero.
	215	.SH DIAGNOSTICS
	216	All error messages are directed to the
	217	.IR TIFFError (3TIFF)
	218	routine.
	219	.PP
	220	.BR "Sorry, can not handle %d-bit pictures" .
	221	The image had
	222	.I BitsPerSample
	223	other than 1, 2, 4, 8, or 16.
	224	.PP
	225	.BR "Sorry, can not handle %d-channel images" .
	226	The image had
	227	.I SamplesPerPixel
	228	other than 1, 3, or 4.
	229	.PP
	230	\fBMissing needed "PhotometricInterpretation" tag\fP.
	231	The image did not have a tag that describes how to display
	232	the data.
	233	.PP
	234	\fBNo "PhotometricInterpretation" tag, assuming RGB\fP.
	235	The image was missing a tag that describes how to display it,
	236	but because it has 3 or 4 samples/pixel, it is assumed to be
	237	.SM RGB.
	238	.PP
	239	\fBNo "PhotometricInterpretation" tag, assuming min-is-black\fP.
	240	The image was missing a tag that describes how to display it,
	241	but because it has 1 sample/pixel, it is assumed to be a grayscale
	242	or bilevel image.
	243	.PP
	244	.BR "No space for photometric conversion table" .
	245	There was insufficient memory for a table used to convert
	246	image samples to 8-bit
	247	.SM RGB.
	248	.PP
	249	\fBMissing required "Colormap" tag\fP.
	250	A Palette image did not have a required
	251	.I Colormap
	252	tag.
	253	.PP
	254	.BR "No space for tile buffer" .
	255	There was insufficient memory to allocate an i/o buffer.
	256	.PP
	257	.BR "No space for strip buffer" .
	258	There was insufficient memory to allocate an i/o buffer.
	259	.PP
	260	.BR "Can not handle format" .
	261	The image has a format (combination of
	262	.IR BitsPerSample ,
	263	.IR SamplesPerPixel ,
	264	and
	265	.IR PhotometricInterpretation )
	266	that can not be handled.
	267	.PP
	268	.BR "No space for B&W mapping table" .
	269	There was insufficient memory to allocate a table used to map
	270	grayscale data to
	271	.SM RGB.
	272	.PP
	273	.BR "No space for Palette mapping table" .
	274	There was insufficient memory to allocate a table used to map
	275	data to 8-bit
	276	.SM RGB.
	277	.SH "SEE ALSO"
	278	.BR TIFFOpen (3TIFF),
	279	.BR TIFFReadRGBAImage (3TIFF),
	280	.BR TIFFReadRGBAImageOriented (3TIFF),
	281	.BR TIFFReadRGBAStrip (3TIFF),
	282	.BR TIFFReadRGBATile (3TIFF),
	283	.BR libtiff (3TIFF)
	284	.PP
	285	Libtiff library home page:
	286	.BR http://www.remotesensing.org/libtiff/