1<!-- Creator : groff version 1.18.1 --> 2<!-- CreationDate: Sat Feb 24 18:37:17 2007 --> 3<html> 4<head> 5<meta name="generator" content="groff -Thtml, see www.gnu.org"> 6<meta name="Content-Style" content="text/css"> 7<title>TIFFRGBAImage</title> 8</head> 9<body> 10 11<h1 align=center>TIFFRGBAImage</h1> 12<a href="#NAME">NAME</a><br> 13<a href="#SYNOPSIS">SYNOPSIS</a><br> 14<a href="#DESCRIPTION">DESCRIPTION</a><br> 15<a href="#ALTERNATE RASTER FORMATS">ALTERNATE RASTER FORMATS</a><br> 16<a href="#SIMULTANEOUS RASTER STORE AND DISPLAY">SIMULTANEOUS RASTER STORE AND DISPLAY</a><br> 17<a href="#SUPPORTING ADDITIONAL TIFF FORMATS">SUPPORTING ADDITIONAL TIFF FORMATS</a><br> 18<a href="#NOTES">NOTES</a><br> 19<a href="#RETURN VALUES">RETURN VALUES</a><br> 20<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br> 21<a href="#SEE ALSO">SEE ALSO</a><br> 22 23<hr> 24<a name="NAME"></a> 25<h2>NAME</h2> 26<!-- INDENTATION --> 27<table width="100%" border=0 rules="none" frame="void" 28 cols="2" cellspacing="0" cellpadding="0"> 29<tr valign="top" align="left"> 30<td width="8%"></td> 31<td width="91%"> 32<p>TIFFRGBAImageOK, TIFFRGBAImageBegin, TIFFRGBAImageGet, 33TIFFRGBAImageEnd − read and decode an image into a 34raster</p> 35</td> 36</table> 37<a name="SYNOPSIS"></a> 38<h2>SYNOPSIS</h2> 39<!-- INDENTATION --> 40<table width="100%" border=0 rules="none" frame="void" 41 cols="2" cellspacing="0" cellpadding="0"> 42<tr valign="top" align="left"> 43<td width="8%"></td> 44<td width="91%"> 45<p><b>#include <tiffio.h></b></p> 46<!-- INDENTATION --> 47<p><b>typedef unsigned char TIFFRGBValue; typedef struct 48_TIFFRGBAImage TIFFRGBAImage;</b></p> 49<!-- INDENTATION --> 50<p><b>int TIFFRGBAImageOK(TIFF *</b><i>tif</i><b>, char</b> 51<i>emsg[1024]</i><b>)<br> 52int TIFFRGBAImageBegin(TIFFRGBAImage *</b><i>img</i><b>, 53TIFF*</b> <i>tif</i><b>, int</b> <i>stopOnError</i><b>, 54char</b> <i>emsg[1024]</i><b>)<br> 55int TIFFRGBAImageGet(TIFFRGBAImage *</b><i>img</i><b>, 56uint32*</b> <i>raster</i><b>, uint32</b> <i>width</i> <b>, 57uint32</b> <i>height</i><b>)<br> 58void TIFFRGBAImageEnd(TIFFRGBAImage 59*</b><i>img</i><b>)</b></p> 60</td> 61</table> 62<a name="DESCRIPTION"></a> 63<h2>DESCRIPTION</h2> 64<!-- INDENTATION --> 65<table width="100%" border=0 rules="none" frame="void" 66 cols="2" cellspacing="0" cellpadding="0"> 67<tr valign="top" align="left"> 68<td width="8%"></td> 69<td width="91%"> 70<p>The routines described here provide a high-level 71interface through which <small>TIFF</small> images may be 72read into memory. Images may be strip- or tile-based and 73have a variety of different characteristics: bits/sample, 74samples/pixel, photometric, etc. Decoding state is 75encapsulated in a <i>TIFFRGBAImage</i> structure making it 76possible to capture state for multiple images and quickly 77switch between them. The target raster format can be 78customized to a particular application’s needs by 79installing custom routines that manipulate image data 80according to application requirements.</p> 81<!-- INDENTATION --> 82<p>The default usage for these routines is: check if an 83image can be processed using <i>TIFFRGBAImageOK</i>, 84construct a decoder state block using 85<i>TIFFRGBAImageBegin</i>, read and decode an image into a 86target raster using <i>TIFFRGBAImageGet</i>, and then 87release resources using <i>TIFFRGBAImageEnd</i>. 88<i>TIFFRGBAImageGet</i> can be called multiple times to 89decode an image using different state parameters. If 90multiple images are to be displayed and there is not enough 91space for each of the decoded rasters, multiple state blocks 92can be managed and then calls can be made to 93<i>TIFFRGBAImageGet</i> as needed to display an image.</p> 94<!-- INDENTATION --> 95<p>The generated raster is assumed to be an array of 96<i>width</i> times <i>height</i> 32-bit entries, where 97<i>width</i> must be less than or equal to the width of the 98image (<i>height</i> may be any non-zero size). If the 99raster dimensions are smaller than the image, the image data 100is cropped to the raster bounds. If the raster height is 101greater than that of the image, then the image data are 102placed in the lower part of the raster. (Note that the 103raster is assume to be organized such that the pixel at 104location (<i>x</i>,<i>y</i>) is 105<i>raster</i>[<i>y</i>*<i>width</i>+<i>x</i>]; with the 106raster origin in the <b>lower-left</b> hand corner.)</p> 107<!-- INDENTATION --> 108<p>Raster pixels are 8-bit packed red, green, blue, alpha 109samples. The macros <i>TIFFGetR</i>, <i>TIFFGetG</i>, 110<i>TIFFGetB</i>, and <i>TIFFGetA</i> should be used to 111access individual samples. Images without Associated Alpha 112matting information have a constant Alpha of 1.0 (255).</p> 113<!-- INDENTATION --> 114<p><i>TIFFRGBAImageGet</i> converts non-8-bit images by 115scaling sample values. Palette, grayscale, bilevel, 116<small>CMYK</small> , and YCbCr images are converted to 117<small>RGB</small> transparently. Raster pixels are returned 118uncorrected by any colorimetry information present in the 119directory.</p> 120<!-- INDENTATION --> 121<p>The parameter <i>stopOnError</i> specifies how to act if 122an error is encountered while reading the image. If 123<i>stopOnError</i> is non-zero, then an error will terminate 124the operation; otherwise <i>TIFFRGBAImageGet</i> will 125continue processing data until all the possible data in the 126image have been requested.</p> 127</td> 128</table> 129<a name="ALTERNATE RASTER FORMATS"></a> 130<h2>ALTERNATE RASTER FORMATS</h2> 131<!-- INDENTATION --> 132<table width="100%" border=0 rules="none" frame="void" 133 cols="2" cellspacing="0" cellpadding="0"> 134<tr valign="top" align="left"> 135<td width="8%"></td> 136<td width="91%"> 137<p>To use the core support for reading and processing 138<small>TIFF</small> images, but write the resulting raster 139data in a different format one need only override the 140‘‘<i>put methods</i>’’ used to store 141raster data. These methods are are defined in the 142<i>TIFFRGBAImage</i> structure and initially setup by 143<i>TIFFRGBAImageBegin</i> to point to routines that pack 144raster data in the default <small>ABGR</small> pixel format. 145Two different routines are used according to the physical 146organization of the image data in the file: 147<i>PlanarConfiguration</i>=1 (packed samples), and 148<i>PlanarConfiguration</i>=2 (separated samples). Note that 149this mechanism can be used to transform the data before 150storing it in the raster. For example one can convert data 151to colormap indices for display on a colormap display.</p> 152</td> 153</table> 154<a name="SIMULTANEOUS RASTER STORE AND DISPLAY"></a> 155<h2>SIMULTANEOUS RASTER STORE AND DISPLAY</h2> 156<!-- INDENTATION --> 157<table width="100%" border=0 rules="none" frame="void" 158 cols="2" cellspacing="0" cellpadding="0"> 159<tr valign="top" align="left"> 160<td width="8%"></td> 161<td width="91%"> 162<p>It is simple to display an image as it is being read into 163memory by overriding the put methods as described above for 164supporting alternate raster formats. Simply keep a reference 165to the default put methods setup by 166<i>TIFFRGBAImageBegin</i> and then invoke them before or 167after each display operation. For example, the 168<i>tiffgt</i>(1) utility uses the following put method to 169update the display as the raster is being filled:</p> 170<!-- INDENTATION --> 171<pre>static void 172putContigAndDraw(TIFFRGBAImage* img, uint32* raster, 173 uint32 x, uint32 y, uint32 w, uint32 h, 174 int32 fromskew, int32 toskew, 175 unsigned char* cp) 176{ 177 (*putContig)(img, raster, x, y, w, h, fromskew, toskew, cp); 178 if (x+w == width) { 179 w = width; 180 if (img->orientation == ORIENTATION_TOPLEFT) 181 lrectwrite(0, y-(h-1), w-1, y, raster-x-(h-1)*w); 182 else 183 lrectwrite(0, y, w-1, y+h-1, raster); 184 } 185} 186</pre> 187<!-- INDENTATION --> 188<p>(the original routine provided by the library is saved in 189the variable <i>putContig</i>.)</p> 190</td> 191</table> 192<a name="SUPPORTING ADDITIONAL TIFF FORMATS"></a> 193<h2>SUPPORTING ADDITIONAL TIFF FORMATS</h2> 194<!-- INDENTATION --> 195<table width="100%" border=0 rules="none" frame="void" 196 cols="2" cellspacing="0" cellpadding="0"> 197<tr valign="top" align="left"> 198<td width="8%"></td> 199<td width="91%"> 200<p>The <i>TIFFRGBAImage</i> routines support the most 201commonly encountered flavors of <small>TIFF.</small> It is 202possible to extend this support by overriding the 203‘‘<i>get method</i>’’ invoked by 204<i>TIFFRGBAImageGet</i> to read <small>TIFF</small> image 205data. Details of doing this are a bit involved, it is best 206to make a copy of an existing get method and modify it to 207suit the needs of an application.</p> 208</td> 209</table> 210<a name="NOTES"></a> 211<h2>NOTES</h2> 212<!-- INDENTATION --> 213<table width="100%" border=0 rules="none" frame="void" 214 cols="2" cellspacing="0" cellpadding="0"> 215<tr valign="top" align="left"> 216<td width="8%"></td> 217<td width="91%"> 218<p>Samples must be either 1, 2, 4, 8, or 16 bits. 219Colorimetric samples/pixel must be either 1, 3, or 4 (i.e. 220<i>SamplesPerPixel</i> minus <i>ExtraSamples</i>).</p> 221<!-- INDENTATION --> 222<p>Palette image colormaps that appear to be incorrectly 223written as 8-bit values are automatically scaled to 22416-bits.</p> 225</td> 226</table> 227<a name="RETURN VALUES"></a> 228<h2>RETURN VALUES</h2> 229<!-- INDENTATION --> 230<table width="100%" border=0 rules="none" frame="void" 231 cols="2" cellspacing="0" cellpadding="0"> 232<tr valign="top" align="left"> 233<td width="8%"></td> 234<td width="91%"> 235<p>All routines return 1 if the operation was successful. 236Otherwise, 0 is returned if an error was encountered and 237<i>stopOnError</i> is zero.</p> 238</td> 239</table> 240<a name="DIAGNOSTICS"></a> 241<h2>DIAGNOSTICS</h2> 242<!-- INDENTATION --> 243<table width="100%" border=0 rules="none" frame="void" 244 cols="2" cellspacing="0" cellpadding="0"> 245<tr valign="top" align="left"> 246<td width="8%"></td> 247<td width="91%"> 248<p>All error messages are directed to the 249<i>TIFFError</i>(3TIFF) routine.</p> 250<!-- INDENTATION --> 251<p><b>Sorry, can not handle %d-bit pictures</b>. The image 252had <i>BitsPerSample</i> other than 1, 2, 4, 8, or 16.</p> 253<!-- INDENTATION --> 254<p><b>Sorry, can not handle %d-channel images</b>. The image 255had <i>SamplesPerPixel</i> other than 1, 3, or 4.</p> 256<!-- INDENTATION --> 257<p><b>Missing needed "PhotometricInterpretation" 258tag</b>. The image did not have a tag that describes how to 259display the data.</p> 260<!-- INDENTATION --> 261<p><b>No "PhotometricInterpretation" tag, assuming 262RGB</b>. The image was missing a tag that describes how to 263display it, but because it has 3 or 4 samples/pixel, it is 264assumed to be <small>RGB.</small></p> 265<!-- INDENTATION --> 266<p><b>No "PhotometricInterpretation" tag, assuming 267min-is-black</b>. The image was missing a tag that describes 268how to display it, but because it has 1 sample/pixel, it is 269assumed to be a grayscale or bilevel image.</p> 270<!-- INDENTATION --> 271<p><b>No space for photometric conversion table</b>. There 272was insufficient memory for a table used to convert image 273samples to 8-bit <small>RGB.</small></p> 274<!-- INDENTATION --> 275<p><b>Missing required "Colormap" tag</b>. A 276Palette image did not have a required <i>Colormap</i> 277tag.</p> 278<!-- INDENTATION --> 279<p><b>No space for tile buffer</b>. There was insufficient 280memory to allocate an i/o buffer.</p> 281<!-- INDENTATION --> 282<p><b>No space for strip buffer</b>. There was insufficient 283memory to allocate an i/o buffer.</p> 284<!-- INDENTATION --> 285<p><b>Can not handle format</b>. The image has a format 286(combination of <i>BitsPerSample</i>, 287<i>SamplesPerPixel</i>, and 288<i>PhotometricInterpretation</i>) that can not be 289handled.</p> 290<!-- INDENTATION --> 291<p><b>No space for B&W mapping table</b>. There was 292insufficient memory to allocate a table used to map 293grayscale data to <small>RGB.</small></p> 294<!-- INDENTATION --> 295<p><b>No space for Palette mapping table</b>. There was 296insufficient memory to allocate a table used to map data to 2978-bit <small>RGB.</small></p> 298</td> 299</table> 300<a name="SEE ALSO"></a> 301<h2>SEE ALSO</h2> 302<!-- INDENTATION --> 303<table width="100%" border=0 rules="none" frame="void" 304 cols="2" cellspacing="0" cellpadding="0"> 305<tr valign="top" align="left"> 306<td width="8%"></td> 307<td width="91%"> 308<p><b>TIFFOpen</b>(3TIFF), <b>TIFFReadRGBAImage</b>(3TIFF), 309<b>TIFFReadRGBAImageOriented</b>(3TIFF), 310<b>TIFFReadRGBAStrip</b>(3TIFF), 311<b>TIFFReadRGBATile</b>(3TIFF), <b>libtiff</b>(3TIFF)</p> 312<!-- INDENTATION --> 313<p>Libtiff library home page: 314<b>http://www.simplesystems.org/libtiff/</b></p> 315</td> 316</table> 317<hr> 318</body> 319</html> 320