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DRC 0c23b0ad60 Various doc tweaks 
- "Optimized baseline entropy coding" = "Huffman table optimization"

  "Optimized baseline entropy coding" was meant to emphasize that the
  feature is only useful when generating baseline (single-scan lossy
  8-bit-per-sample Huffman-coded) JPEG images, because it is
  automatically enabled when generating Huffman-coded progressive
  (multi-scan), 12-bit-per-sample, and lossless JPEG images.  However,
  Huffman table optimization isn't actually an integral part of those
  non-baseline modes.  You can forego Huffman table optimization with
  12-bit data precision if you supply your own Huffman tables.  The spec
  doesn't require it with progressive or lossless mode, either, although
  our implementation does.  Furthermore, "baseline" describes more than
  just the type of entropy coding used.  It was incorrect to say that
  optimized "baseline" entropy coding is automatically enabled for
  Huffman-coded progressive, 12-bit-per-sample, and lossless JPEG
  images, since those are clearly not baseline images.

- "Progressive entropy coding" = "Progressive JPEG"

  "Progressive" describes more than just the type of entropy coding
  used.  (In fact, both Huffman-coded and arithmetic-coded images can be
  progressive.)

- Mention that TJPARAM_OPTIMIZE/TJ.PARAM_OPTIMIZE can be used with
  lossless transformation as well.

- General wordsmithing

- Formatting tweaks
2024-08-16 11:49:00 -04:00

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<a href="#pub-attribs">Data Fields</a> </div>
<div class="headertitle"><div class="title">tjtransform Struct Reference<div class="ingroups"><a class="el" href="group___turbo_j_p_e_g.html">TurboJPEG</a></div></div></div>
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<div class="contents">
<p>Lossless transform.
<a href="structtjtransform.html#details">More...</a></p>
<p><code>#include &lt;turbojpeg.h&gt;</code></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a id="pub-attribs" name="pub-attribs"></a>
Data Fields</h2></td></tr>
<tr class="memitem:ac324e5e442abec8a961e5bf219db12cf" id="r_ac324e5e442abec8a961e5bf219db12cf"><td class="memItemLeft" align="right" valign="top"><a class="el" href="structtjregion.html">tjregion</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structtjtransform.html#ac324e5e442abec8a961e5bf219db12cf">r</a></td></tr>
<tr class="memdesc:ac324e5e442abec8a961e5bf219db12cf"><td class="mdescLeft">&#160;</td><td class="mdescRight">Cropping region. <br /></td></tr>
<tr class="separator:ac324e5e442abec8a961e5bf219db12cf"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a2525aab4ba6978a1c273f74fef50e498" id="r_a2525aab4ba6978a1c273f74fef50e498"><td class="memItemLeft" align="right" valign="top">int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structtjtransform.html#a2525aab4ba6978a1c273f74fef50e498">op</a></td></tr>
<tr class="memdesc:a2525aab4ba6978a1c273f74fef50e498"><td class="mdescLeft">&#160;</td><td class="mdescRight">One of the <a class="el" href="group___turbo_j_p_e_g.html#ga2de531af4e7e6c4f124908376b354866">transform operations</a>. <br /></td></tr>
<tr class="separator:a2525aab4ba6978a1c273f74fef50e498"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ac0e74655baa4402209a21e1ae481c8f6" id="r_ac0e74655baa4402209a21e1ae481c8f6"><td class="memItemLeft" align="right" valign="top">int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structtjtransform.html#ac0e74655baa4402209a21e1ae481c8f6">options</a></td></tr>
<tr class="memdesc:ac0e74655baa4402209a21e1ae481c8f6"><td class="mdescLeft">&#160;</td><td class="mdescRight">The bitwise OR of one of more of the <a class="el" href="group___turbo_j_p_e_g.html#gaecaaa3b7e2af812592c015d83207f010">transform options</a>. <br /></td></tr>
<tr class="separator:ac0e74655baa4402209a21e1ae481c8f6"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a688fe8f1a8ecc12a538d9e561cf338e3" id="r_a688fe8f1a8ecc12a538d9e561cf338e3"><td class="memItemLeft" align="right" valign="top">void *&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structtjtransform.html#a688fe8f1a8ecc12a538d9e561cf338e3">data</a></td></tr>
<tr class="memdesc:a688fe8f1a8ecc12a538d9e561cf338e3"><td class="mdescLeft">&#160;</td><td class="mdescRight">Arbitrary data that can be accessed within the body of the callback function. <br /></td></tr>
<tr class="separator:a688fe8f1a8ecc12a538d9e561cf338e3"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a0dc7697d59a7abe48afc629e96cbc1d2" id="r_a0dc7697d59a7abe48afc629e96cbc1d2"><td class="memItemLeft" align="right" valign="top">int(*&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="structtjtransform.html#a0dc7697d59a7abe48afc629e96cbc1d2">customFilter</a> )(short *coeffs, <a class="el" href="structtjregion.html">tjregion</a> arrayRegion, <a class="el" href="structtjregion.html">tjregion</a> planeRegion, int componentID, int transformID, struct <a class="el" href="structtjtransform.html">tjtransform</a> *transform)</td></tr>
<tr class="memdesc:a0dc7697d59a7abe48afc629e96cbc1d2"><td class="mdescLeft">&#160;</td><td class="mdescRight">A callback function that can be used to modify the DCT coefficients after they are losslessly transformed but before they are transcoded to a new JPEG image. <br /></td></tr>
<tr class="separator:a0dc7697d59a7abe48afc629e96cbc1d2"><td class="memSeparator" colspan="2">&#160;</td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Lossless transform. </p>
</div><h2 class="groupheader">Field Documentation</h2>
<a id="a0dc7697d59a7abe48afc629e96cbc1d2" name="a0dc7697d59a7abe48afc629e96cbc1d2"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a0dc7697d59a7abe48afc629e96cbc1d2">&#9670;&#160;</a></span>customFilter</h2>
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<td class="memname">int(* tjtransform::customFilter) (short *coeffs, <a class="el" href="structtjregion.html">tjregion</a> arrayRegion, <a class="el" href="structtjregion.html">tjregion</a> planeRegion, int componentID, int transformID, struct <a class="el" href="structtjtransform.html">tjtransform</a> *transform)</td>
</tr>
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<p>A callback function that can be used to modify the DCT coefficients after they are losslessly transformed but before they are transcoded to a new JPEG image. </p>
<p>This allows for custom filters or other transformations to be applied in the frequency domain.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">coeffs</td><td>pointer to an array of transformed DCT coefficients. (NOTE: This pointer is not guaranteed to be valid once the callback returns, so applications wishing to hand off the DCT coefficients to another function or library should make a copy of them within the body of the callback.)</td></tr>
<tr><td class="paramname">arrayRegion</td><td><a class="el" href="structtjregion.html" title="Cropping region.">tjregion</a> structure containing the width and height of the array pointed to by <code>coeffs</code> as well as its offset relative to the component plane. TurboJPEG implementations may choose to split each component plane into multiple DCT coefficient arrays and call the callback function once for each array.</td></tr>
<tr><td class="paramname">planeRegion</td><td><a class="el" href="structtjregion.html" title="Cropping region.">tjregion</a> structure containing the width and height of the component plane to which <code>coeffs</code> belongs</td></tr>
<tr><td class="paramname">componentID</td><td>ID number of the component plane to which <code>coeffs</code> belongs. (Y, Cb, and Cr have, respectively, ID's of 0, 1, and 2 in typical JPEG images.)</td></tr>
<tr><td class="paramname">transformID</td><td>ID number of the transformed image to which <code>coeffs</code> belongs. This is the same as the index of the transform in the <code>transforms</code> array that was passed to <a class="el" href="group___turbo_j_p_e_g.html#gaff23ba1dcabed456794b844791613920" title="Losslessly transform a JPEG image into another JPEG image.">tj3Transform()</a>.</td></tr>
<tr><td class="paramname">transform</td><td>a pointer to a <a class="el" href="structtjtransform.html" title="Lossless transform.">tjtransform</a> structure that specifies the parameters and/or cropping region for this transform</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>0 if the callback was successful, or -1 if an error occurred. </dd></dl>
</div>
</div>
<a id="a688fe8f1a8ecc12a538d9e561cf338e3" name="a688fe8f1a8ecc12a538d9e561cf338e3"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a688fe8f1a8ecc12a538d9e561cf338e3">&#9670;&#160;</a></span>data</h2>
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<td class="memname">void* tjtransform::data</td>
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<p>Arbitrary data that can be accessed within the body of the callback function. </p>
</div>
</div>
<a id="a2525aab4ba6978a1c273f74fef50e498" name="a2525aab4ba6978a1c273f74fef50e498"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a2525aab4ba6978a1c273f74fef50e498">&#9670;&#160;</a></span>op</h2>
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<td class="memname">int tjtransform::op</td>
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<p>One of the <a class="el" href="group___turbo_j_p_e_g.html#ga2de531af4e7e6c4f124908376b354866">transform operations</a>. </p>
</div>
</div>
<a id="ac0e74655baa4402209a21e1ae481c8f6" name="ac0e74655baa4402209a21e1ae481c8f6"></a>
<h2 class="memtitle"><span class="permalink"><a href="#ac0e74655baa4402209a21e1ae481c8f6">&#9670;&#160;</a></span>options</h2>
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<td class="memname">int tjtransform::options</td>
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<p>The bitwise OR of one of more of the <a class="el" href="group___turbo_j_p_e_g.html#gaecaaa3b7e2af812592c015d83207f010">transform options</a>. </p>
</div>
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<a id="ac324e5e442abec8a961e5bf219db12cf" name="ac324e5e442abec8a961e5bf219db12cf"></a>
<h2 class="memtitle"><span class="permalink"><a href="#ac324e5e442abec8a961e5bf219db12cf">&#9670;&#160;</a></span>r</h2>
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<td class="memname"><a class="el" href="structtjregion.html">tjregion</a> tjtransform::r</td>
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<p>Cropping region. </p>
</div>
</div>
<hr/>The documentation for this struct was generated from the following file:<ul>
<li><b>turbojpeg.h</b></li>
</ul>
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