06b1fd6374
now properly supports all possible orientations, i.e. images will be flipped both in horizontal and vertical directions if required. 'Know bugs' section now removed from the appropriate manual pages. Closed bug entry: http://bugzilla.remotesensing.org/show_bug.cgi?id=322
278 lines
8.9 KiB
Plaintext
278 lines
8.9 KiB
Plaintext
.\" $Header: /cvs/maptools/cvsroot/libtiff/man/Attic/TIFFRGBAImage.3t,v 1.4 2003-12-03 15:39:34 dron Exp $
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.\"
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.\" Copyright (c) 1991-1997 Sam Leffler
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.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
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.\"
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.\" Permission to use, copy, modify, distribute, and sell this software and
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.\" its documentation for any purpose is hereby granted without fee, provided
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.\" that (i) the above copyright notices and this permission notice appear in
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.\" all copies of the software and related documentation, and (ii) the names of
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.\" Sam Leffler and Silicon Graphics may not be used in any advertising or
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.\" publicity relating to the software without the specific, prior written
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.\" permission of Sam Leffler and Silicon Graphics.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
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.\" EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
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.\" WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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.\"
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.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
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.\" ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
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.\" OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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.\" WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
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.\" LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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.\" OF THIS SOFTWARE.
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.\"
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.if n .po 0
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.TH TIFFRGBAImage 3T "October 15, 1995"
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.SH NAME
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TIFFRGBAImage \- read and decode an image into a raster
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.SH SYNOPSIS
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.nf
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.B "#include <tiffio.h>"
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.B "typedef unsigned char TIFFRGBValue;"
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.B "typedef struct _TIFFRGBAImage TIFFRGBAImage;"
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.B "int TIFFRGBAImageOK(TIFF* tif, char emsg[1024]);"
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.B "int TIFFRGBAImageBegin(TIFFRGBAImage* img, TIFF* tif, int stopOnError, char emsg[1024]);"
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.B "int TIFFRGBAImageGet(TIFFRGBAImage* img, uint32* raster, uint32 width, uint32 height);"
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.B "void TIFFRGBAImageEnd(TIFFRGBAImage* img);"
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.SH DESCRIPTION
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The routines described here provide a high-level interface
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through which
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.SM TIFF
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images may be read into memory.
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Images may be strip- or tile-based and have a variety of different
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characteristics: bits/sample, samples/pixel, photometric, etc.
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Decoding state is encapsulated in a
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.I TIFFRGBAImage
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structure making it possible to capture state for multiple images
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and quickly switch between them.
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The target raster format can be customized to a particular application's
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needs by installing custom routines that manipulate image data
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according to application requirements.
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.PP
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The default usage for these routines is: check if an image can
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be processed using
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.IR TIFFRGBAImageOK ,
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construct a decoder state block using
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.IR TIFFRGBAImageBegin ,
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read and decode an image into a target raster using
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.IR TIFFRGBAImageGet ,
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and then
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release resources using
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.IR TIFFRGBAImageEnd .
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.I TIFFRGBAImageGet
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can be called multiple times to decode an image using different
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state parameters.
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If multiple images are to be displayed and there is not enough
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space for each of the decoded rasters, multiple state blocks can
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be managed and then calls can be made to
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.I TIFFRGBAImageGet
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as needed to display an image.
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.PP
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The generated raster is assumed to be an array of
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.I width
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times
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.I height
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32-bit entries, where
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.I width
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must be less than or equal to the width of the image (\c
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.I height
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may be any non-zero size).
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If the raster dimensions are smaller than the image, the image data
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is cropped to the raster bounds.
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If the raster height is greater than that of the image, then the
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image data are placed in the lower part of the raster.
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(Note that the raster is assume to be organized such that the pixel
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at location (\fIx\fP,\fIy\fP) is \fIraster\fP[\fIy\fP*\fIwidth\fP+\fIx\fP];
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with the raster origin in the
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.B lower-left
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hand corner.)
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.PP
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Raster pixels are 8-bit packed red, green, blue, alpha samples.
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The macros
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.IR TIFFGetR ,
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.IR TIFFGetG ,
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.IR TIFFGetB ,
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and
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.I TIFFGetA
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should be used to access individual samples.
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Images without Associated Alpha matting information have a constant
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Alpha of 1.0 (255).
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.PP
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.I TIFFRGBAImageGet
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converts non-8-bit images by scaling sample values.
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Palette, grayscale, bilevel,
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.SM CMYK\c
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, and YCbCr images are converted to
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.SM RGB
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transparently.
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Raster pixels are returned uncorrected by any colorimetry information
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present in the directory.
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.PP
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The paramater
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.I stopOnError
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specifies how to act if an error is encountered while reading
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the image.
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If
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.I stopOnError
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is non-zero, then an error will terminate the operation; otherwise
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.I TIFFRGBAImageGet
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will continue processing data until all the possible data in the
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image have been requested.
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.SH "ALTERNATE RASTER FORMATS"
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To use the core support for reading and processing
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.SM TIFF
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images, but write the resulting raster data in a different format
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one need only override the ``\fIput methods\fP'' used to store raster data.
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These methods are are defined in the
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.I TIFFRGBAImage
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structure and initially setup by
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.I TIFFRGBAImageBegin
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to point to routines that pack raster data in the default
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.SM ABGR
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pixel format.
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Two different routines are used according to the physical organization
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of the image data in the file:
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.IR PlanarConfiguration =1
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(packed samples),
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and
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.IR PlanarConfiguration =2
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(separated samples).
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Note that this mechanism can be used to transform the data before
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storing it in the raster.
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For example one can convert data
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to colormap indices for display on a colormap display.
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.SH "SIMULTANEOUS RASTER STORE AND DISPLAY"
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It is simple to display an image as it is being read into memory
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by overriding the put methods as described above for supporting
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alternate raster formats.
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Simply keep a reference to the default put methods setup by
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.I TIFFRGBAImageBegin
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and then invoke them before or after each display operation.
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For example, the
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.IR tiffgt (1)
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utility uses the following put method to update the display as
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the raster is being filled:
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.sp
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.nf
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.ft C
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static void
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putContigAndDraw(TIFFRGBAImage* img, uint32* raster,
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uint32 x, uint32 y, uint32 w, uint32 h,
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int32 fromskew, int32 toskew,
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unsigned char* cp)
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{
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(*putContig)(img, raster, x, y, w, h, fromskew, toskew, cp);
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if (x+w == width) {
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w = width;
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if (img->orientation == ORIENTATION_TOPLEFT)
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lrectwrite(0, y-(h-1), w-1, y, raster-x-(h-1)*w);
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else
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lrectwrite(0, y, w-1, y+h-1, raster);
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}
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}
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.ft R
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.fi
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.sp
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(the original routine provided by the library is saved in the
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variable
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.IR putContig .)
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.SH "SUPPORTING ADDITIONAL TIFF FORMATS"
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The
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.I TIFFRGBAImage
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routines support the most commonly encountered flavors of
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.SM TIFF.
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It is possible to extend this support by overriding the ``\fIget method\fP''
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invoked by
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.I TIFFRGBAImageGet
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to read
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.SM TIFF
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image data.
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Details of doing this are a bit involved, it is best to make a copy
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of an existing get method and modify it to suit the needs of an
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application.
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.SH NOTES
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Samples must be either 1, 2, 4, 8, or 16 bits.
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Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
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.I SamplesPerPixel
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minus
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.IR ExtraSamples ).
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.PP
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Palettte image colormaps that appear to be incorrectly written
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as 8-bit values are automatically scaled to 16-bits.
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.SH "RETURN VALUES"
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All routines return
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1 if the operation was successful.
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Otherwise, 0 is returned if an error was encountered and
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.I stopOnError
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is zero.
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.SH DIAGNOSTICS
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All error messages are directed to the
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.IR TIFFError (3T)
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routine.
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.PP
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.BR "Sorry, can not handle %d-bit pictures" .
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The image had
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.I BitsPerSample
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other than 1, 2, 4, 8, or 16.
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.PP
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.BR "Sorry, can not handle %d-channel images" .
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The image had
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.I SamplesPerPixel
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other than 1, 3, or 4.
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.PP
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\fBMissing needed "PhotometricInterpretation" tag\fP.
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The image did not have a tag that describes how to display
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the data.
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.PP
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\fBNo "PhotometricInterpretation" tag, assuming RGB\fP.
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The image was missing a tag that describes how to display it,
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but because it has 3 or 4 samples/pixel, it is assumed to be
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.SM RGB.
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.PP
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\fBNo "PhotometricInterpretation" tag, assuming min-is-black\fP.
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The image was missing a tag that describes how to display it,
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but because it has 1 sample/pixel, it is assumed to be a grayscale
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or bilevel image.
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.PP
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.BR "No space for photometric conversion table" .
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There was insufficient memory for a table used to convert
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image samples to 8-bit
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.SM RGB.
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.PP
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\fBMissing required "Colormap" tag\fP.
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A Palette image did not have a required
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.I Colormap
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tag.
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.PP
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.BR "No space for tile buffer" .
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There was insufficient memory to allocate an i/o buffer.
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.PP
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.BR "No space for strip buffer" .
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There was insufficient memory to allocate an i/o buffer.
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.PP
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.BR "Can not handle format" .
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The image has a format (combination of
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.IR BitsPerSample ,
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.IR SamplesPerPixel ,
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and
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.IR PhotometricInterpretation )
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that can not be handled.
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.PP
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.BR "No space for B&W mapping table" .
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There was insufficient memory to allocate a table used to map
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grayscale data to
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.SM RGB.
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.PP
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.BR "No space for Palette mapping table" .
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There was insufficient memory to allocate a table used to map
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data to 8-bit
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.SM RGB.
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.SH "SEE ALSO"
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.IR libtiff (3T),
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.IR TIFFOpen (3T),
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.IR TIFFReadRGBAImage (3T),
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.IR TIFFReadRGBAImageOriented (3T),
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.IR TIFFReadRGBAStrip (3T),
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.IR TIFFReadRGBATile (3T)
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