src/parsec/disk-image/parsec/parsec-benchmark/pkgs/apps/vips/src/doc/html/vipsmanualse2.html - public/gem5-resources - Git at Google

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   <h3 class="sectionHead"><span class="titlemark">1.2    </span> <a
  id="x7-70001.2"></a>The VIPS file format</h3>
 <!--l. 3--><p class="noindent" >VIPS has its own very simple file format. It is used inside
 VIPS to hold images during computation. You can save
 images in VIPS format if you want, but the VIPS format is
 not widely used and you may have problems reading your
 images into other packages.
 <!--l. 8--><p class="indent" >  If you intend to keep an image, it&#8217;s much better to save it
 as TIFF, JPEG, PNG, PBM/PGM/PPM or HDR. VIPS can
 transparently read and write all these formats.
 <!--l. 12--><p class="noindent" >
   <h4 class="subsectionHead"><span class="titlemark">1.2.1    </span> <a
  id="x7-80001.2.1"></a>VIPS file header</h4>
 <!--l. 15--><p class="noindent" >All VIPS image files start with a 64-byte header giving
 basic information about the image dimensions, see
 Table&#x00A0;<a
 href="#x7-80011">1.1<!--tex4ht:ref: fg:header --></a>. This is followed by the image data. This is
 usually just the pixel values in native format (ie. the byte
 order used by the machine that wrote the file) laid out
 left-to-right and top-to-bottom. After the image data comes
 a block of optional XML which holds extra image metadata,
 such as ICC profiles and image history. You can use the
 command-line program <span class="obeylines-h"><span class="verb"><span
 class="pcrr7t-">header</span></span></span> to extract the XML
 from an image and <span class="obeylines-h"><span class="verb"><span
 class="pcrr7t-">edvips</span></span></span> to replace it, see the man
 pages.
 <!--l. 24--><p class="indent" >  The <span
 class="pcrr7t-">Type </span>field, the <span
 class="pcrr7t-">Xres</span>/<span
 class="pcrr7t-">Yres </span>fields, and the
 <span
 class="pcrr7t-">Xoffset</span>/<span
 class="pcrr7t-">Yoffset </span>fields are advisory. VIPS maintains
 their value (if you convert an image to <span
 class="ptmri7t-">CIE</span><span
 class="ptmri7t-">&#x00A0;</span><span
 class="cmmi-10">L</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">a</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">b</span><span
 class="cmsy-7">*</span>
 colour space with <span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_XYZ2Lab()</span>, for example, VIPS
 will set <span
 class="pcrr7t-">Type </span>to be <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LAB</span>), but never uses
 these values itself in determining the action of an image
 processing function. These fields are to help the user and to
 help application programs built on VIPS which are
 trying to present image data to the user in a meaningful
 way.
 <!--l. 33--><p class="indent" >  The <span
 class="pcrr7t-">BandFmt</span>, <span
 class="pcrr7t-">Coding </span>and <span
 class="pcrr7t-">Type </span>fields can take the
 values shown in tables&#x00A0;<a
 href="#x7-80022">1.2<!--tex4ht:ref: fg:bandfmt --></a>, <a
 href="#x7-80033">1.3<!--tex4ht:ref: fg:coding --></a> and <a
 href="#x7-80044">1.4<!--tex4ht:ref: fg:type --></a>. The C++ and
 Python names for these values are slightly different, for
 historical reasons.


 <!--l. 39--><p class="indent" >  <a
  id="x7-80011"></a><hr class="float"><div class="float"
 >


 <div class="center"
 >
 <!--l. 39--><p class="noindent" >
 <div class="tabular"> <table id="TBL-1" class="tabular"
 cellspacing="0" cellpadding="0" rules="groups"
 ><colgroup id="TBL-1-1g"><col
 id="TBL-1-1"></colgroup><colgroup id="TBL-1-2g"><col
 id="TBL-1-2"></colgroup><colgroup id="TBL-1-3g"><col
 id="TBL-1-3"></colgroup><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-1-1-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-1-1"
 class="td11">Bytes</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-1-2"
 class="td11">Represent                                                      </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-1-3"
 class="td11">VIPS name        </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-1-2-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-2-1"
 class="td11">0&#8211;3    </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-2-2"
 class="td11">VIPS magic number (in hex, 08 f2 f6 b6)    </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-2-3"
 class="td11">           </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-3-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-3-1"
 class="td11">4&#8211;7    </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-3-2"
 class="td11">Number of pels per horizontal line (integer)</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-3-3"
 class="td11"><span
 class="pcrr7t-">Xsize      </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-4-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-4-1"
 class="td11">8&#8211;11  </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-4-2"
 class="td11">Number of horizontal lines (integer)            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-4-3"
 class="td11"><span
 class="pcrr7t-">Ysize      </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-5-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-5-1"
 class="td11">12&#8211;15</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-5-2"
 class="td11">Number of bands (integer)                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-5-3"
 class="td11"><span
 class="pcrr7t-">Bands      </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-6-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-6-1"
 class="td11">16&#8211;19</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-6-2"
 class="td11">Unused (legacy)                                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-6-3"
 class="td11"><span
 class="pcrr7t-">Bbits      </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-7-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-7-1"
 class="td11">20&#8211;23</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-7-2"
 class="td11">Band format (eg. <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_USHORT</span>)</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-7-3"
 class="td11"><span
 class="pcrr7t-">BandFmt    </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-8-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-8-1"
 class="td11">24&#8211;27</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-8-2"
 class="td11">Coding type (eg. <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_NONE</span>)        </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-8-3"
 class="td11"><span
 class="pcrr7t-">Coding     </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-9-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-9-1"
 class="td11">28&#8211;31</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-9-2"
 class="td11">Type (eg. <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LAB</span>)                           </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-9-3"
 class="td11"><span
 class="pcrr7t-">Type       </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-10-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-10-1"
 class="td11">32&#8211;35</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-10-2"
 class="td11">Horizontal resolution (float, pixels mm<sup><span
 class="cmsy-7">-</span><span
 class="cmr-7">1</span></sup>)  </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-10-3"
 class="td11"><span
 class="pcrr7t-">Xres       </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-11-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-11-1"
 class="td11">36&#8211;39</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-11-2"
 class="td11">Vertical resolution (float, pixels mm<sup><span
 class="cmsy-7">-</span><span
 class="cmr-7">1</span></sup>)       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-11-3"
 class="td11"><span
 class="pcrr7t-">Yres       </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-12-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-12-1"
 class="td11">40&#8211;43</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-12-2"
 class="td11">Unused (legacy)                                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-12-3"
 class="td11"><span
 class="pcrr7t-">Length     </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-13-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-13-1"
 class="td11">44&#8211;45</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-13-2"
 class="td11">Unused (legacy)                                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-13-3"
 class="td11"><span
 class="pcrr7t-">Compression</span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-14-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-14-1"
 class="td11">46&#8211;47</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-14-2"
 class="td11">Unused (legacy)                                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-14-3"
 class="td11"><span
 class="pcrr7t-">Level      </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-15-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-15-1"
 class="td11">48&#8211;51</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-15-2"
 class="td11">Horizontal offset of origin                            </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-15-3"
 class="td11"><span
 class="pcrr7t-">Xoffset    </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-16-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-16-1"
 class="td11">52&#8211;55</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-16-2"
 class="td11">Vertical offset of origin                                 </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-16-3"
 class="td11"><span
 class="pcrr7t-">Yoffset    </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-1-17-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-17-1"
 class="td11">56&#8211;63</td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-17-2"
 class="td11">For future expansion (all zeros for now)       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-1-17-3"
 class="td11">           </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-1-18-"><td  style="white-space:nowrap; text-align:left;" id="TBL-1-18-1"
 class="td11">    </td></tr></table></div></div>
 <br /><div class="caption"
 ><span class="id">Table&#x00A0;1.1: </span><span
 class="content">VIPS header</span></div><!--tex4ht:label?: x7-80011 -->


   </div><hr class="endfloat" />


 <!--l. 67--><p class="indent" >  <a
  id="x7-80022"></a><hr class="float"><div class="float"
 >


 <div class="center"
 >
 <!--l. 67--><p class="noindent" >
 <div class="tabular"> <table id="TBL-2" class="tabular"
 cellspacing="0" cellpadding="0" rules="groups"
 ><colgroup id="TBL-2-1g"><col
 id="TBL-2-1"></colgroup><colgroup id="TBL-2-2g"><col
 id="TBL-2-2"></colgroup><colgroup id="TBL-2-3g"><col
 id="TBL-2-3"></colgroup><colgroup id="TBL-2-4g"><col
 id="TBL-2-4"></colgroup><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-2-1-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-1-1"
 class="td11"><span
 class="pcrr7t-">BandFmt             </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-1-2"
 class="td11">C++ and Python name</td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-1-3"
 class="td11">Value</td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-1-4"
 class="td11">Meaning                   </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-2-2-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-2-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_NOTSET   </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-2-2"
 class="td11"><span
 class="pcrr7t-">FMTNOTSET      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-2-3"
 class="td11">-1      </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-2-4"
 class="td11">              </td></tr><tr
  style="vertical-align:baseline;" id="TBL-2-3-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-3-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_UCHAR </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-3-2"
 class="td11"><span
 class="pcrr7t-">FMTUCHAR </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-3-3"
 class="td11">0 </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-3-4"
 class="td11">Unsigned 8-bit int</td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-4-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-4-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_CHAR     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-4-2"
 class="td11"><span
 class="pcrr7t-">FMTCHAR        </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-4-3"
 class="td11">1       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-4-4"
 class="td11">Signed 8-bit int         </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-5-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-5-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_USHORT   </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-5-2"
 class="td11"><span
 class="pcrr7t-">FMTUSHORT      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-5-3"
 class="td11">2       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-5-4"
 class="td11">Unsigned 16-bit int   </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-6-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-6-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_SHORT    </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-6-2"
 class="td11"><span
 class="pcrr7t-">FMTSHORT       </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-6-3"
 class="td11">3       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-6-4"
 class="td11">Signed 16-bit int       </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-7-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-7-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_UINT     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-7-2"
 class="td11"><span
 class="pcrr7t-">FMTUINT        </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-7-3"
 class="td11">4       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-7-4"
 class="td11">Unsigned 32-bit int   </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-8-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-8-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_INT      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-8-2"
 class="td11"><span
 class="pcrr7t-">FMTINT         </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-8-3"
 class="td11">5       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-8-4"
 class="td11">Signed 32-bit int       </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-9-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-9-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_FLOAT    </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-9-2"
 class="td11"><span
 class="pcrr7t-">FMTFLOAT       </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-9-3"
 class="td11">6       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-9-4"
 class="td11">32-bit IEEE float      </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-10-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-10-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_COMPLEX  </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-10-2"
 class="td11"><span
 class="pcrr7t-">FMTCOMPLEX     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-10-3"
 class="td11">7       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-10-4"
 class="td11">Complex (2 floats)    </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-11-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-11-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_DOUBLE   </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-11-2"
 class="td11"><span
 class="pcrr7t-">FMTDOUBLE      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-11-3"
 class="td11">8       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-11-4"
 class="td11">64-bit IEEE double   </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-2-12-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-12-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_BANDFMT</span><span
 class="pcrr7t-">_DPCOMPLEX</span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-12-2"
 class="td11"><span
 class="pcrr7t-">FMTDPCOMPLEX   </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-12-3"
 class="td11">9       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-2-12-4"
 class="td11">Complex (2 doubles)</td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-2-13-"><td  style="white-space:nowrap; text-align:left;" id="TBL-2-13-1"
 class="td11">                    </td></tr></table></div></div>
 <br /><div class="caption"
 ><span class="id">Table&#x00A0;1.2: </span><span
 class="content">Possible values for <span
 class="pcrr7t-">BandFmt</span></span></div><!--tex4ht:label?: x7-80022 -->


   </div><hr class="endfloat" />


 <!--l. 90--><p class="indent" >  <a
  id="x7-80033"></a><hr class="float"><div class="float"
 >


 <div class="center"
 >
 <!--l. 90--><p class="noindent" >
 <div class="tabular"><table id="TBL-3" class="tabular"
 cellspacing="0" cellpadding="0" rules="groups"
 ><colgroup id="TBL-3-1g"><col
 id="TBL-3-1"></colgroup><colgroup id="TBL-3-2g"><col
 id="TBL-3-2"></colgroup><colgroup id="TBL-3-3g"><col
 id="TBL-3-3"></colgroup><colgroup id="TBL-3-4g"><col
 id="TBL-3-4"></colgroup><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-3-1-"><td  style="white-space:nowrap; text-align:left;" id="TBL-3-1-1"
 class="td11"><span
 class="pcrr7t-">Coding        </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-1-2"
 class="td11">C++ and Python name</td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-1-3"
 class="td11">Value</td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-1-4"
 class="td11">Meaning                           </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-3-2-"><td  style="white-space:nowrap; text-align:left;" id="TBL-3-2-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_NONE</span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-2-2"
 class="td11"><span
 class="pcrr7t-">NOCODING       </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-2-3"
 class="td11">0       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-2-4"
 class="td11">VIPS computation format</td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-3-3-"><td  style="white-space:nowrap; text-align:left;" id="TBL-3-3-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_LABQ</span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-3-2"
 class="td11"><span
 class="pcrr7t-">LABQ           </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-3-3"
 class="td11">2       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-3-4"
 class="td11">LABQ storage format      </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-3-4-"><td  style="white-space:nowrap; text-align:left;" id="TBL-3-4-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_RAD </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-4-2"
 class="td11"><span
 class="pcrr7t-">RAD            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-4-3"
 class="td11">6       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-3-4-4"
 class="td11">Radiance storage format  </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-3-5-"><td  style="white-space:nowrap; text-align:left;" id="TBL-3-5-1"
 class="td11">              </td></tr></table></div></div>
 <br /><div class="caption"
 ><span class="id">Table&#x00A0;1.3: </span><span
 class="content">Possible values for <span
 class="pcrr7t-">Coding</span></span></div><!--tex4ht:label?: x7-80033 -->


   </div><hr class="endfloat" />


 <!--l. 105--><p class="indent" >  <a
  id="x7-80044"></a><hr class="float"><div class="float"
 >


 <div class="center"
 >
 <!--l. 105--><p class="noindent" >
 <div class="tabular"><table id="TBL-4" class="tabular"
 cellspacing="0" cellpadding="0" rules="groups"
 ><colgroup id="TBL-4-1g"><col
 id="TBL-4-1"></colgroup><colgroup id="TBL-4-2g"><col
 id="TBL-4-2"></colgroup><colgroup id="TBL-4-3g"><col
 id="TBL-4-3"></colgroup><colgroup id="TBL-4-4g"><col
 id="TBL-4-4"></colgroup><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-4-1-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-1-1"
 class="td11"><span
 class="pcrr7t-">Type             </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-1-2"
 class="td11">C++ and Python name</td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-1-3"
 class="td11">Value</td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-1-4"
 class="td11">Meaning                           </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-4-2-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-2-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_MULTIBAND</span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-2-2"
 class="td11"><span
 class="pcrr7t-">MULTIBAND      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-2-3"
 class="td11">0       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-2-4"
 class="td11">Some multiband image    </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-3-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-3-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_B</span><span
 class="pcrr7t-">_W      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-3-2"
 class="td11"><span
 class="pcrr7t-">B</span><span
 class="pcrr7t-">_W            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-3-3"
 class="td11">1       </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-3-4"
 class="td11">Some single band image  </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-4-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-4-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_HISTOGRAM</span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-4-2"
 class="td11"><span
 class="pcrr7t-">HISTOGRAM      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-4-3"
 class="td11">10     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-4-4"
 class="td11">Histogram or LUT           </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-5-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-5-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_FOURIER  </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-5-2"
 class="td11"><span
 class="pcrr7t-">FOURIER        </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-5-3"
 class="td11">24     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-5-4"
 class="td11">Image in Fourier space     </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-6-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-6-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_XYZ      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-6-2"
 class="td11"><span
 class="pcrr7t-">XYZ            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-6-3"
 class="td11">12     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-6-4"
 class="td11"><span
 class="ptmri7t-">CIE XYZ </span>colour space      </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-7-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-7-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LAB      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-7-2"
 class="td11"><span
 class="pcrr7t-">LAB            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-7-3"
 class="td11">13     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-7-4"
 class="td11"><span
 class="ptmri7t-">CIE</span><span
 class="ptmri7t-">&#x00A0;</span><span
 class="cmmi-10">L</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">a</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">b</span><span
 class="cmsy-7">*</span> colour space</td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-8-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-8-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_CMYK     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-8-2"
 class="td11"><span
 class="pcrr7t-">CMYK           </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-8-3"
 class="td11">15     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-8-4"
 class="td11"><span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_icc</span><span
 class="pcrr7t-">_export()  </span></td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-9-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-9-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LABQ     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-9-2"
 class="td11"><span
 class="pcrr7t-">LABQ           </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-9-3"
 class="td11">16     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-9-4"
 class="td11">32-bit <span
 class="ptmri7t-">CIE</span><span
 class="ptmri7t-">&#x00A0;</span><span
 class="cmmi-10">L</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">a</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">b</span><span
 class="cmsy-7">*</span>    </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-10-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-10-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_RGB      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-10-2"
 class="td11"><span
 class="pcrr7t-">RGB            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-10-3"
 class="td11">17     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-10-4"
 class="td11">Some RGB                       </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-11-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-11-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_UCS      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-11-2"
 class="td11"><span
 class="pcrr7t-">UCS            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-11-3"
 class="td11">18     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-11-4"
 class="td11"><span
 class="ptmri7t-">UCS(1:1) </span>colour space     </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-12-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-12-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LCH      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-12-2"
 class="td11"><span
 class="pcrr7t-">LCH            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-12-3"
 class="td11">19     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-12-4"
 class="td11"><span
 class="ptmri7t-">CIE LCh </span>colour space      </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-13-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-13-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_LABS     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-13-2"
 class="td11"><span
 class="pcrr7t-">LABS           </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-13-3"
 class="td11">21     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-13-4"
 class="td11">48-bit <span
 class="ptmri7t-">CIE</span><span
 class="ptmri7t-">&#x00A0;</span><span
 class="cmmi-10">L</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">a</span><span
 class="cmsy-7">*</span><span
 class="cmmi-10">b</span><span
 class="cmsy-7">*</span>    </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-14-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-14-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_sRGB     </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-14-2"
 class="td11"><span
 class="pcrr7t-">sRGB           </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-14-3"
 class="td11">22     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-14-4"
 class="td11">sRGB colour space           </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-15-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-15-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_YXY      </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-15-2"
 class="td11"><span
 class="pcrr7t-">YXY            </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-15-3"
 class="td11">23     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-15-4"
 class="td11"><span
 class="ptmri7t-">CIE Yxy </span>colour space       </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-16-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-16-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_RGB16    </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-16-2"
 class="td11"><span
 class="pcrr7t-">RGB16          </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-16-3"
 class="td11">25     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-16-4"
 class="td11">16-bit RGB                       </td>
 </tr><tr
  style="vertical-align:baseline;" id="TBL-4-17-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-17-1"
 class="td11"><span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_TYPE</span><span
 class="pcrr7t-">_GREY16   </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-17-2"
 class="td11"><span
 class="pcrr7t-">GREY16         </span></td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-17-3"
 class="td11">26     </td><td  style="white-space:nowrap; text-align:left;" id="TBL-4-17-4"
 class="td11">16-bit monochrome          </td>
 </tr><tr
 class="hline"><td><hr></td><td><hr></td><td><hr></td><td><hr></td></tr><tr
  style="vertical-align:baseline;" id="TBL-4-18-"><td  style="white-space:nowrap; text-align:left;" id="TBL-4-18-1"
 class="td11">                 </td></tr></table></div></div>
 <br /><div class="caption"
 ><span class="id">Table&#x00A0;1.4: </span><span
 class="content">Possible values for <span
 class="pcrr7t-">Type</span></span></div><!--tex4ht:label?: x7-80044 -->


   </div><hr class="endfloat" />
   <h4 class="subsectionHead"><span class="titlemark">1.2.2    </span> <a
  id="x7-90001.2.2"></a>Computation formats</h4>
 <!--l. 134--><p class="noindent" >This type of image has <span
 class="pcrr7t-">Coding </span>set to <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_NONE</span>.
 The header is then followed by a large array of pixels, laid
 out left-to-right, top-to-bottom. Each pixel contains the
 specified number of bands. Each band has the specified
 band format, which may be an 8-, 16- or 32-bit integer
 (either signed or unsigned), a single or double precision
 IEEE floating point number, or a pair of single or double
 precision floats forming a complex number.
 <!--l. 142--><p class="indent" >  All values are stored in the host-machine&#8217;s native number
 representation (that is, either most-significant first, as in
 SPARC and 680x0 machines, or least-significant first,
 for Intel and DEC machines). If necessary, the VIPS
 library will automatically byte-swap for you during
 read.
 <!--l. 147--><p class="noindent" >
   <h4 class="subsectionHead"><span class="titlemark">1.2.3    </span> <a
  id="x7-100001.2.3"></a>Storage formats</h4>
 <!--l. 149--><p class="noindent" >All storage formats have other values for the <span
 class="pcrr7t-">Coding</span>
 field. This release supports <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_LABQ </span>and
 <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_RAD</span>.
 <!--l. 152--><p class="indent" >  <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_LABQ </span>stores <span
 class="cmmi-10">L</span><sup><span
 class="cmsy-7">*</span></sup>, <span
 class="cmmi-10">a</span><sup><span
 class="cmsy-7">*</span></sup> and <span
 class="cmmi-10">b</span><sup><span
 class="cmsy-7">*</span></sup> for each
 pixel, with 10 bits for <span
 class="cmmi-10">L</span><sup><span
 class="cmsy-7">*</span></sup> and 11 bits for each of <span
 class="cmmi-10">a</span><sup><span
 class="cmsy-7">*</span></sup>
 and <span
 class="cmmi-10">b</span><sup><span
 class="cmsy-7">*</span></sup>. These 32 bits are packed into 4 bytes, with
 the most significant 8 bits of each value in the first 3
 bytes, and the left-over bits packed into the final byte as
 2:3:3.
 <!--l. 158--><p class="indent" >  This format is a little awkward to process. Some VIPS
 functions can work directly on <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_LABQ</span>
 images (<span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_extract</span><span
 class="pcrr7t-">_area()</span>, for example), but
 most will require you to unpack the image to one of the
 computation formats (for example with <span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_LabQ2Lab()</span>)
 first.
 <!--l. 163--><p class="indent" >  <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_RAD </span>stores <span
 class="cmmi-10">RGB </span>or <span
 class="cmmi-10">XY Z </span>float images
 as 8 bytes of mantissa and then 8 bytes of exponent,
 shared between the three channels. This coding style
 is used by the Radiance family of programs (and the
 HDR format) commonly used for HDR imaging. This
 style of image is generated when you load an HDR
 image.
 <!--l. 169--><p class="indent" >  This format is a little awkward to process. Some VIPS
 functions can work directly on <span
 class="pcrr7t-">IM</span><span
 class="pcrr7t-">_CODING</span><span
 class="pcrr7t-">_RAD</span>
 images (<span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_extract</span><span
 class="pcrr7t-">_area()</span>, for example), but
 most will require you to unpack the image to one of     the computation formats with <span
 class="pcrr7t-">im</span><span
 class="pcrr7t-">_rad2float()</span>
  first.


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