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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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                  <a href="#libvips-mosaicing.description" class="shortcut">Description</a></span>
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<div class="refentry">
<a name="libvips-mosaicing"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="libvips-mosaicing.top_of_page"></a>mosaicing</span></h2>
<p>mosaicing — build image mosaics</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="libvips-mosaicing.stability-level"></a><h2>Stability Level</h2>
<acronym title="The intention of a Stable interface is to enable arbitrary third parties to
develop applications to these interfaces, release them, and have confidence that
they will run on all minor releases of the product (after the one in which the
interface was introduced, and within the same major release). Even at a major
release, incompatible changes are expected to be rare, and to have strong
justifications.
"><span class="acronym">Stable</span></acronym>, unless otherwise indicated
</div>
<div class="refsect1">
<a name="libvips-mosaicing.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()">vips_merge</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-mosaic" title="vips_mosaic ()">vips_mosaic</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-mosaic1" title="vips_mosaic1 ()">vips_mosaic1</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-match" title="vips_match ()">vips_match</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()">vips_globalbalance</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="libvips-mosaicing.html#vips-remosaic" title="vips_remosaic ()">vips_remosaic</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="libvips-mosaicing.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include &lt;vips/vips.h&gt;
</pre>
</div>
<div class="refsect1">
<a name="libvips-mosaicing.description"></a><h2>Description</h2>
<p>These functions are useful for joining many small images together to make
one large image. They can cope with unstable contrast and arbitary sub-image
layout, but will not do any geometric correction. Geometric errors should
be removed before using these functions.</p>
<p>The mosaicing functions can be grouped into layers:</p>
<p>The lowest level functions are <code class="function">im_correl()</code> and <a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()"><code class="function">vips_merge()</code></a>.
<code class="function">im_correl()</code> 
searches a large image for a small sub-image, returning
the position of the best sub-image match. <a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()"><code class="function">vips_merge()</code></a> 
joins two images together
left-right or up-down with a smooth seam.</p>
<p>Next, <a class="link" href="libvips-mosaicing.html#vips-mosaic" title="vips_mosaic ()"><code class="function">vips_mosaic()</code></a> use the
search function plus the two low-level merge operations to join two images 
given just an approximate overlap as a start point. </p>
<p>The functions <code class="function">im_lrmosaic1()</code> and <code class="function">im_tbmosaic1()</code> are
first-order
analogues of the basic mosaic functions: they take two approximate 
tie-points and use
them to rotate and scale the right-hand or bottom image before starting to
join.</p>
<p>Finally, <a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()"><code class="function">vips_globalbalance()</code></a> can be used to remove contrast differences in 
a mosaic
which has been assembled with these functions. It takes the mosaic apart,
measures image contrast differences along the seams, finds a set of
correction factors which will minimise these differences, and reassembles
the mosaic.
<code class="function">im_remosaic()</code> uses the
same
techniques, but will reassemble the image from a different set of source
images.</p>
</div>
<div class="refsect1">
<a name="libvips-mosaicing.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="vips-merge"></a><h3>vips_merge ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_merge (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *ref</code></em>,
            <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *sec</code></em>,
            <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
            <em class="parameter"><code><a class="link" href="libvips-conversion.html#VipsDirection" title="enum VipsDirection"><span class="type">VipsDirection</span></a> direction</code></em>,
            <em class="parameter"><code><span class="type">int</span> dx</code></em>,
            <em class="parameter"><code><span class="type">int</span> dy</code></em>,
            <em class="parameter"><code>...</code></em>);</pre>
<p>Optional arguments:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><em class="parameter"><code>mblend</code></em>
: <code class="literal">gint</code>, maximum blend size </p></li></ul></div>
<p>This operation joins two images left-right (with <em class="parameter"><code>ref</code></em>
 on the left) or
up-down (with <em class="parameter"><code>ref</code></em>
 above) with a smooth seam.</p>
<p>If the number of bands differs, one of the images 
must have one band. In this case, an n-band image is formed from the 
one-band image by joining n copies of the one-band image together, and then
the two n-band images are operated upon.</p>
<p>The two input images are cast up to the smallest common type (see table 
Smallest common format in </p>
<a class="link" href="libvips-arithmetic.html" title="arithmetic">arithmetic</a>).
<p><em class="parameter"><code>dx</code></em>
 and <em class="parameter"><code>dy</code></em>
 give the displacement of <em class="parameter"><code>sec</code></em>
 relative to <em class="parameter"><code>ref</code></em>
, in other words,
the vector to get from the origin of <em class="parameter"><code>sec</code></em>
 to the origin of <em class="parameter"><code>ref</code></em>
, in other
words, <em class="parameter"><code>dx</code></em>
 will generally be a negative number. </p>
<p><em class="parameter"><code>mblend</code></em>
 limits  the  maximum width of the
blend area.  A value of "-1" means "unlimited". The two images are blended 
with a raised cosine. </p>
<p>Pixels with all bands equal to zero are "transparent", that
is, zero pixels in the overlap area do not  contribute  to  the  merge.
This makes it possible to join non-rectangular images.</p>
<p>See also: <a class="link" href="libvips-mosaicing.html#vips-mosaic" title="vips_mosaic ()"><code class="function">vips_mosaic()</code></a>, <a class="link" href="libvips-conversion.html#vips-insert" title="vips_insert ()"><code class="function">vips_insert()</code></a>.</p>
<div class="refsect3">
<a name="vips-merge.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>ref</p></td>
<td class="parameter_description"><p>reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>sec</p></td>
<td class="parameter_description"><p>secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>direction</p></td>
<td class="parameter_description"><p>horizontal or vertical merge</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>dx</p></td>
<td class="parameter_description"><p>displacement of ref from sec</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>dy</p></td>
<td class="parameter_description"><p>displacement of ref from sec</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-merge.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-mosaic"></a><h3>vips_mosaic ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_mosaic (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *ref</code></em>,
             <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *sec</code></em>,
             <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
             <em class="parameter"><code><a class="link" href="libvips-conversion.html#VipsDirection" title="enum VipsDirection"><span class="type">VipsDirection</span></a> direction</code></em>,
             <em class="parameter"><code><span class="type">int</span> xref</code></em>,
             <em class="parameter"><code><span class="type">int</span> yref</code></em>,
             <em class="parameter"><code><span class="type">int</span> xsec</code></em>,
             <em class="parameter"><code><span class="type">int</span> ysec</code></em>,
             <em class="parameter"><code>...</code></em>);</pre>
<p>Optional arguments:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p><em class="parameter"><code>bandno</code></em>
: <code class="literal">gint</code>, band to search for features</p></li>
<li class="listitem"><p><em class="parameter"><code>hwindow</code></em>
: <code class="literal">gint</code>, half window size</p></li>
<li class="listitem"><p><em class="parameter"><code>harea</code></em>
: <code class="literal">gint</code>, half search size </p></li>
<li class="listitem"><p><em class="parameter"><code>mblend</code></em>
: <code class="literal">gint</code>, maximum blend size</p></li>
</ul></div>
<p>This operation joins two images left-right (with <em class="parameter"><code>ref</code></em>
 on the left) or
top-bottom (with <em class="parameter"><code>ref</code></em>
 above) given an approximate overlap.</p>
<p><em class="parameter"><code>sec</code></em>
 is positioned so that the pixel (<em class="parameter"><code>xsec</code></em>
, <em class="parameter"><code>ysec</code></em>
) in <em class="parameter"><code>sec</code></em>
 lies on top of 
the pixel (<em class="parameter"><code>xref</code></em>
, <em class="parameter"><code>yref</code></em>
) in <em class="parameter"><code>ref</code></em>
. The overlap area is divided into three
sections, 20 high-contrast points in band <em class="parameter"><code>bandno</code></em>
 of image <em class="parameter"><code>ref</code></em>
 are found 
in each, and each high-contrast point is searched for in <em class="parameter"><code>sec</code></em>
 using
<em class="parameter"><code>hwindow</code></em>
 and <em class="parameter"><code>harea</code></em>
 (see <code class="function">vips_correl()</code>). </p>
<p>A linear model is fitted to the 60 tie-points, points a long way from the
fit are discarded, and the model refitted until either too few points
remain or the model reaches good agreement. </p>
<p>The detected displacement is used with <a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()"><code class="function">vips_merge()</code></a> to join the two images
together. </p>
<p>See also: <a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()"><code class="function">vips_merge()</code></a>, <a class="link" href="libvips-conversion.html#vips-insert" title="vips_insert ()"><code class="function">vips_insert()</code></a>.</p>
<div class="refsect3">
<a name="vips-mosaic.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>ref</p></td>
<td class="parameter_description"><p>reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>sec</p></td>
<td class="parameter_description"><p>secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>direction</p></td>
<td class="parameter_description"><p>horizontal or vertical join</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xref</p></td>
<td class="parameter_description"><p>position in reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>yref</p></td>
<td class="parameter_description"><p>position in reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xsec</p></td>
<td class="parameter_description"><p>position in secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ysec</p></td>
<td class="parameter_description"><p>position in secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-mosaic.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-mosaic1"></a><h3>vips_mosaic1 ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_mosaic1 (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *ref</code></em>,
              <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *sec</code></em>,
              <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
              <em class="parameter"><code><a class="link" href="libvips-conversion.html#VipsDirection" title="enum VipsDirection"><span class="type">VipsDirection</span></a> direction</code></em>,
              <em class="parameter"><code><span class="type">int</span> xr1</code></em>,
              <em class="parameter"><code><span class="type">int</span> yr1</code></em>,
              <em class="parameter"><code><span class="type">int</span> xs1</code></em>,
              <em class="parameter"><code><span class="type">int</span> ys1</code></em>,
              <em class="parameter"><code><span class="type">int</span> xr2</code></em>,
              <em class="parameter"><code><span class="type">int</span> yr2</code></em>,
              <em class="parameter"><code><span class="type">int</span> xs2</code></em>,
              <em class="parameter"><code><span class="type">int</span> ys2</code></em>,
              <em class="parameter"><code>...</code></em>);</pre>
<p>Optional arguments:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p><em class="parameter"><code>search</code></em>
: search to improve tie-points</p></li>
<li class="listitem"><p><em class="parameter"><code>hwindow</code></em>
: half window size</p></li>
<li class="listitem"><p><em class="parameter"><code>harea</code></em>
: half search size </p></li>
<li class="listitem"><p><em class="parameter"><code>interpolate</code></em>
: interpolate pixels with this</p></li>
<li class="listitem"><p><em class="parameter"><code>mblend</code></em>
: maximum blend size </p></li>
<li class="listitem"><p><em class="parameter"><code>bandno</code></em>
: band to search for features</p></li>
</ul></div>
<p>This operation joins two images top-bottom (with <em class="parameter"><code>sec</code></em>
 on the right) 
or left-right (with <em class="parameter"><code>sec</code></em>
 at the bottom)
given an approximate pair of tie-points. <em class="parameter"><code>sec</code></em>
 is scaled and rotated as
necessary before the join.</p>
<p>Before performing the transformation, the tie-points are improved by 
searching band <em class="parameter"><code>bandno</code></em>
 in an area of <em class="parameter"><code>sec</code></em>
 of size <em class="parameter"><code>hsearchsize</code></em>
 for a
match of size <em class="parameter"><code>hwindowsize</code></em>
 to <em class="parameter"><code>ref</code></em>
. </p>
<p>If <em class="parameter"><code>search</code></em>
 is <code class="literal">TRUE</code>, before performing the transformation, the tie-points 
are improved by searching an area of <em class="parameter"><code>sec</code></em>
 of size <em class="parameter"><code>harea</code></em>
 for a
mosaic1 of size <em class="parameter"><code>hwindow</code></em>
 to <em class="parameter"><code>ref</code></em>
. </p>
<p><em class="parameter"><code>mblend</code></em>
 limits  the  maximum size of the
blend area.  A value of "-1" means "unlimited". The two images are blended 
with a raised cosine. </p>
<p>Pixels with all bands equal to zero are "transparent", that
is, zero pixels in the overlap area do not  contribute  to  the  merge.
This makes it possible to join non-rectangular images.</p>
<p>If the number of bands differs, one of the images 
must have one band. In this case, an n-band image is formed from the 
one-band image by joining n copies of the one-band image together, and then
the two n-band images are operated upon.</p>
<p>The two input images are cast up to the smallest common type (see table 
Smallest common format in </p>
<a class="link" href="libvips-arithmetic.html" title="arithmetic">arithmetic</a>).
<p>See also: <a class="link" href="libvips-mosaicing.html#vips-merge" title="vips_merge ()"><code class="function">vips_merge()</code></a>, <a class="link" href="libvips-conversion.html#vips-insert" title="vips_insert ()"><code class="function">vips_insert()</code></a>, <a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()"><code class="function">vips_globalbalance()</code></a>.</p>
<div class="refsect3">
<a name="vips-mosaic1.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>ref</p></td>
<td class="parameter_description"><p>reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>sec</p></td>
<td class="parameter_description"><p>secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>direction</p></td>
<td class="parameter_description"><p>horizontal or vertical join</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xr1</p></td>
<td class="parameter_description"><p>first reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>yr1</p></td>
<td class="parameter_description"><p>first reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xs1</p></td>
<td class="parameter_description"><p>first secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ys1</p></td>
<td class="parameter_description"><p>first secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xr2</p></td>
<td class="parameter_description"><p>second reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>yr2</p></td>
<td class="parameter_description"><p>second reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xs2</p></td>
<td class="parameter_description"><p>second secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ys2</p></td>
<td class="parameter_description"><p>second secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-mosaic1.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-match"></a><h3>vips_match ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_match (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *ref</code></em>,
            <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *sec</code></em>,
            <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
            <em class="parameter"><code><span class="type">int</span> xr1</code></em>,
            <em class="parameter"><code><span class="type">int</span> yr1</code></em>,
            <em class="parameter"><code><span class="type">int</span> xs1</code></em>,
            <em class="parameter"><code><span class="type">int</span> ys1</code></em>,
            <em class="parameter"><code><span class="type">int</span> xr2</code></em>,
            <em class="parameter"><code><span class="type">int</span> yr2</code></em>,
            <em class="parameter"><code><span class="type">int</span> xs2</code></em>,
            <em class="parameter"><code><span class="type">int</span> ys2</code></em>,
            <em class="parameter"><code>...</code></em>);</pre>
<p>Optional arguments:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p><em class="parameter"><code>search</code></em>
: search to improve tie-points</p></li>
<li class="listitem"><p><em class="parameter"><code>hwindow</code></em>
: half window size</p></li>
<li class="listitem"><p><em class="parameter"><code>harea</code></em>
: half search size </p></li>
<li class="listitem"><p><em class="parameter"><code>interpolate</code></em>
: interpolate pixels with this</p></li>
</ul></div>
<p>Scale, rotate and translate <em class="parameter"><code>sec</code></em>
 so that the tie-points line up.</p>
<p>If <em class="parameter"><code>search</code></em>
 is <code class="literal">TRUE</code>, before performing the transformation, the tie-points 
are improved by searching an area of <em class="parameter"><code>sec</code></em>
 of size <em class="parameter"><code>harea</code></em>
 for a
match of size <em class="parameter"><code>hwindow</code></em>
 to <em class="parameter"><code>ref</code></em>
. </p>
<p>This function will only work well for small rotates and scales.</p>
<div class="refsect3">
<a name="vips-match.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>ref</p></td>
<td class="parameter_description"><p>reference image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>sec</p></td>
<td class="parameter_description"><p>secondary image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xr1</p></td>
<td class="parameter_description"><p>first reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>yr1</p></td>
<td class="parameter_description"><p>first reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xs1</p></td>
<td class="parameter_description"><p>first secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ys1</p></td>
<td class="parameter_description"><p>first secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xr2</p></td>
<td class="parameter_description"><p>second reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>yr2</p></td>
<td class="parameter_description"><p>second reference tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>xs2</p></td>
<td class="parameter_description"><p>second secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ys2</p></td>
<td class="parameter_description"><p>second secondary tie-point</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-match.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-globalbalance"></a><h3>vips_globalbalance ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_globalbalance (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *in</code></em>,
                    <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
                    <em class="parameter"><code>...</code></em>);</pre>
<p>Optional arguments:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p><em class="parameter"><code>gamma</code></em>
: gamma of source images</p></li>
<li class="listitem"><p><em class="parameter"><code>int_output</code></em>
: <code class="literal">TRUE</code> for integer image output</p></li>
</ul></div>
<p>vips_globalbalance() can be used to remove contrast differences in 
an assembled mosaic.</p>
<p>It reads the History field attached to <em class="parameter"><code>in</code></em>
 and builds a list of the source
images that were used to make the mosaic and the position that each ended
up at in the final image.</p>
<p>It opens each of the source images in turn and extracts all parts which
overlap with any of the other images. It finds the average values in the
overlap areas and uses least-mean-square to find a set of correction
factors which will minimise overlap differences. It uses <em class="parameter"><code>gamma</code></em>
 to
gamma-correct the source images before calculating the factors. A value of
1.0 will stop this.</p>
<p>Each of the source images is transformed with the appropriate correction 
factor, then the mosaic is reassembled. <em class="parameter"><code>out</code></em>
 is <a class="link" href="VipsImage.html#VIPS-FORMAT-FLOAT:CAPS"><span class="type">VIPS_FORMAT_FLOAT</span></a>, but 
if <em class="parameter"><code>int_output</code></em>
 is set, the output image is the same format as the input
images.  </p>
<p>There are some conditions that must be met before this operation can work:
the source images must all be present under the filenames recorded in the
history on <em class="parameter"><code>in</code></em>
, and the mosaic must have been built using only operations in
this package.</p>
<p>See also: <a class="link" href="libvips-mosaicing.html#vips-remosaic" title="vips_remosaic ()"><code class="function">vips_remosaic()</code></a>.</p>
<div class="refsect3">
<a name="vips-globalbalance.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>in</p></td>
<td class="parameter_description"><p>mosaic to rebuild</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-globalbalance.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-remosaic"></a><h3>vips_remosaic ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_remosaic (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *in</code></em>,
               <em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> **out</code></em>,
               <em class="parameter"><code>const <span class="type">char</span> *old_str</code></em>,
               <em class="parameter"><code>const <span class="type">char</span> *new_str</code></em>,
               <em class="parameter"><code>...</code></em>);</pre>
<p>vips_remosaic() works rather as <a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()"><code class="function">vips_globalbalance()</code></a>. It takes apart the
mosaiced image <em class="parameter"><code>in</code></em>
 and rebuilds it, substituting images.</p>
<p>Unlike <a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()"><code class="function">vips_globalbalance()</code></a>, images are substituted based on their file‐
names.  The  rightmost  occurence  of the string <em class="parameter"><code>old_str</code></em>
 is swapped
for <em class="parameter"><code>new_str</code></em>
, that file is opened, and that image substituted  for
the old image.</p>
<p>It's convenient for multispectral images. You can mosaic one band, then
use that mosaic as a template for mosaicing the others automatically.</p>
<p>See also: <a class="link" href="libvips-mosaicing.html#vips-globalbalance" title="vips_globalbalance ()"><code class="function">vips_globalbalance()</code></a>.</p>
<div class="refsect3">
<a name="vips-remosaic.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>in</p></td>
<td class="parameter_description"><p>mosaic to rebuild</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>out</p></td>
<td class="parameter_description"><p>output image</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>old_str</p></td>
<td class="parameter_description"><p>gamma of source images</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>new_str</p></td>
<td class="parameter_description"><p>gamma of source images</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p><code class="literal">NULL</code>-terminated list of optional named arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-remosaic.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
</div>
<div class="refsect1">
<a name="libvips-mosaicing.other_details"></a><h2>Types and Values</h2>
</div>
</div>
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