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1.\" $Id: TIFFReadRGBAImage.3tiff,v 1.3 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.
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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 TIFFReadRGBAImage 3TIFF "October 29, 2004" "libtiff"
27.SH NAME
28TIFFReadRGBAImage, TIFFReadRGBAImageOriented \- read and decode an image
29into a fixed-format raster
30.SH SYNOPSIS
31.B "#include <tiffio.h>"
32.sp
33.B "#define TIFFGetR(abgr) ((abgr) & 0xff)"
34.br
35.B "#define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)"
36.br
37.B "#define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)"
38.br
39.B "#define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)"
40.sp
41.BI "int TIFFReadRGBAImage(TIFF *" tif ", u_long " width ", u_long " height ", u_long *" raster ", int " stopOnError ")"
42.br
43.BI "int TIFFReadRGBAImageOriented(TIFF *" tif ", u_long " width ", u_long " height ", u_long *" raster ", int " orientation ", int " stopOnError ")"
44.br
45.SH DESCRIPTION
46.IR TIFFReadRGBAImage
47reads a strip- or tile-based image into memory, storing the
48result in the user supplied
49.IR raster .
50The raster is assumed to be an array of
51.I width
52times
53.I height
5432-bit entries, where
55.I width
56must be less than or equal to the width of the image (\c
57.I height
58may be any non-zero size).
59If the raster dimensions are smaller than the image, the image data
60is cropped to the raster bounds.
61If the raster height is greater than that of the image, then the
62image data are placed in the lower part of the raster.
63(Note that the raster is assume to be organized such that the pixel
64at location (\fIx\fP,\fIy\fP) is \fIraster\fP[\fIy\fP*\fIwidth\fP+\fIx\fP];
65with the raster origin in the lower-left hand corner.)
66.PP
67.IR TIFFReadRGBAImageOriented
68works like
69.IR TIFFReadRGBAImage
70with except of that user can specify the raster origin position with the
71.I orientation
72parameter. Four orientations supported:
73.TP
74.B ORIENTATION_TOPLEFT
75origin in top-left corner,
76.TP
77.B ORIENTATION_TOPRIGHT
78origin in top-right corner,
79.TP
80.B ORIENTATION_BOTLEFT
81origin in bottom-left corner
82and
83.TP
84.B ORIENTATION_BOTRIGHT
85origin in bottom-right corner.
86.LP
87If you choose
88.B ORIENTATION_BOTLEFT
89result will be the same as returned by the
90.IR TIFFReadRGBAImage.
91.PP
92Raster pixels are 8-bit packed red, green, blue, alpha samples.
93The macros
94.IR TIFFGetR ,
95.IR TIFFGetG ,
96.IR TIFFGetB ,
97and
98.I TIFFGetA
99should be used to access individual samples.
100Images without Associated Alpha matting information have a constant
101Alpha of 1.0 (255).
102.PP
103.I TIFFReadRGBAImage
104converts non-8-bit images by scaling sample values.
105Palette, grayscale, bilevel,
106.SM CMYK\c
107, and YCbCr images are converted to
108.SM RGB
109transparently.
110Raster pixels are returned uncorrected by any colorimetry information
111present in the directory.
112.PP
113The paramater
114.I stopOnError
115specifies how to act if an error is encountered while reading
116the image.
117If
118.I stopOnError
119is non-zero, then an error will terminate the operation; otherwise
120.I TIFFReadRGBAImage
121will continue processing data until all the possible data in the
122image have been requested.
123.SH NOTES
124In C++ the
125.I stopOnError
126parameter defaults to 0.
127.PP
128Samples must be either 1, 2, 4, 8, or 16 bits.
129Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
130.I SamplesPerPixel
131minus
132.IR ExtraSamples ).
133.PP
134Palettte image colormaps that appear to be incorrectly written
135as 8-bit values are automatically scaled to 16-bits.
136.PP
137.I TIFFReadRGBAImage
138is just a wrapper around the more general
139.IR TIFFRGBAImage (3TIFF)
140facilities.
141.SH "RETURN VALUES"
1421 is returned if the image was successfully read and converted.
143Otherwise, 0 is returned if an error was encountered and
144.I stopOnError
145is zero.
146.SH DIAGNOSTICS
147All error messages are directed to the
148.IR TIFFError (3TIFF)
149routine.
150.PP
151.BR "Sorry, can not handle %d-bit pictures" .
152The image had
153.I BitsPerSample
154other than 1, 2, 4, 8, or 16.
155.PP
156.BR "Sorry, can not handle %d-channel images" .
157The image had
158.I SamplesPerPixel
159other than 1, 3, or 4.
160.PP
161\fBMissing needed "PhotometricInterpretation" tag\fP.
162The image did not have a tag that describes how to display
163the data.
164.PP
165\fBNo "PhotometricInterpretation" tag, assuming RGB\fP.
166The image was missing a tag that describes how to display it,
167but because it has 3 or 4 samples/pixel, it is assumed to be
168.SM RGB.
169.PP
170\fBNo "PhotometricInterpretation" tag, assuming min-is-black\fP.
171The image was missing a tag that describes how to display it,
172but because it has 1 sample/pixel, it is assumed to be a grayscale
173or bilevel image.
174.PP
175.BR "No space for photometric conversion table" .
176There was insufficient memory for a table used to convert
177image samples to 8-bit
178.SM RGB.
179.PP
180\fBMissing required "Colormap" tag\fP.
181A Palette image did not have a required
182.I Colormap
183tag.
184.PP
185.BR "No space for tile buffer" .
186There was insufficient memory to allocate an i/o buffer.
187.PP
188.BR "No space for strip buffer" .
189There was insufficient memory to allocate an i/o buffer.
190.PP
191.BR "Can not handle format" .
192The image has a format (combination of
193.IR BitsPerSample ,
194.IR SamplesPerPixel ,
195and
196.IR PhotometricInterpretation )
197that
198.I TIFFReadRGBAImage
199can not handle.
200.PP
201.BR "No space for B&W mapping table" .
202There was insufficient memory to allocate a table used to map
203grayscale data to
204.SM RGB.
205.PP
206.BR "No space for Palette mapping table" .
207There was insufficient memory to allocate a table used to map
208data to 8-bit
209.SM RGB.
210.SH "SEE ALSO"
211.BR TIFFOpen (3TIFF),
212.BR TIFFRGBAImage (3TIFF),
213.BR TIFFReadRGBAStrip (3TIFF),
214.BR TIFFReadRGBATile (3TIFF),
215.BR libtiff (3TIFF)
216.PP
217Libtiff library home page:
218.BR http://www.remotesensing.org/libtiff/