[gimp-help] Add Mean Curvature Blur filter

[Julien Hardlin <jhardlin src gnome org>]

commit 37f1544dbaa88cdb52bd4fee755249ea577e1c04
Author: Julien Hardelin <jhardlin orange fr>
Date:   Wed Dec 4 15:01:28 2019 +0100

    Add Mean Curvature Blur filter

 images/C/filters/blur/mean_curvature-dialog.png    | Bin 0 -> 17289 bytes
 .../examples/blur/mean_curvature-denoise.jpg       | Bin 0 -> 43606 bytes
 .../filters/examples/blur/mean_curvature-ex-1.jpg  | Bin 0 -> 65225 bytes
 .../filters/examples/blur/mean_curvature-ex-2.jpg  | Bin 0 -> 56706 bytes
 src/filters/blur.xml                               |   1 +
 src/filters/blur/mean-curvature-blur.xml           | 134 +++++++++++++++++++++
 6 files changed, 135 insertions(+)
---
diff --git a/images/C/filters/blur/mean_curvature-dialog.png b/images/C/filters/blur/mean_curvature-dialog.png
new file mode 100644
index 000000000..4067ed1d2
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diff --git a/images/C/filters/examples/blur/mean_curvature-denoise.jpg 
b/images/C/filters/examples/blur/mean_curvature-denoise.jpg
new file mode 100644
index 000000000..046958237
Binary files /dev/null and b/images/C/filters/examples/blur/mean_curvature-denoise.jpg differ
diff --git a/images/C/filters/examples/blur/mean_curvature-ex-1.jpg 
b/images/C/filters/examples/blur/mean_curvature-ex-1.jpg
new file mode 100644
index 000000000..65e713165
Binary files /dev/null and b/images/C/filters/examples/blur/mean_curvature-ex-1.jpg differ
diff --git a/images/C/filters/examples/blur/mean_curvature-ex-2.jpg 
b/images/C/filters/examples/blur/mean_curvature-ex-2.jpg
new file mode 100644
index 000000000..aea29274e
Binary files /dev/null and b/images/C/filters/examples/blur/mean_curvature-ex-2.jpg differ
diff --git a/src/filters/blur.xml b/src/filters/blur.xml
index 770cf6ed0..ccdf05bb6 100644
--- a/src/filters/blur.xml
+++ b/src/filters/blur.xml
@@ -10,6 +10,7 @@
 
   <xi:include href="blur/introduction.xml"/>
   <xi:include href="blur/gauss.xml"/>
+  <xi:include href="blur/mean-curvature-blur.xml"/>
   <xi:include href="blur/median-blur.xml"/>
   <xi:include href="blur/pixelize.xml"/>
   <xi:include href="blur/gauss_select.xml"/>
diff --git a/src/filters/blur/mean-curvature-blur.xml b/src/filters/blur/mean-curvature-blur.xml
new file mode 100644
index 000000000..f35cb1888
--- /dev/null
+++ b/src/filters/blur/mean-curvature-blur.xml
@@ -0,0 +1,134 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE sect2 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
+                       "http://www.docbook.org/xml/4.3/docbookx.dtd";>
+<!-- section history:
+  2019-12-29 j.h : initial version
+-->
+<sect2 id="gimp-filter-mean-curvature-blur">
+  <title>Mean Curvature Blur</title>
+
+  <indexterm>
+    <primary>Filters</primary>
+    <secondary>Blur</secondary>
+    <tertiary>Mean Curvature Blur</tertiary>
+  </indexterm>
+  <indexterm>
+    <primary>Mean Curvature Blur</primary>
+  </indexterm>
+  
+  <sect3>
+    <title>Overview</title>
+    <para>
+      Regularize geometry at a speed proportional to the local mean curvature 
+      value: this filter uses the mean curvature algorithm to blur the image 
+      preserving edges.
+    </para>
+    <para>
+      Mean Curvature algorithm is describes in <ulink 
+      url="https://en.wikipedia.org/wiki/Mean_curvature";>Wikipedia</ulink>
+    </para>
+  </sect3>
+  
+  <sect3>
+    <title>Activate the filter</title>
+    <para>
+      You can find this filter in the image menu under
+      <menuchoice>
+        <guimenu>Filters</guimenu>
+        <guisubmenu>Blur</guisubmenu>
+        <guimenuitem>Mean Curvature Blur…</guimenuitem>
+      </menuchoice>
+    </para>
+  </sect3>
+  
+  <sect3>
+    <title>Options</title>
+    <figure>
+      <title><quote>Mean Curvature Blur</quote> filter parameters</title>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="PNG"
+            fileref="images/filters/blur/mean_curvature-dialog.png"/>
+        </imageobject>
+      </mediaobject>
+    </figure>
+    <variablelist>
+      <varlistentry>
+        <term><guilabel>Presets</guilabel>, <guilabel>Preview</guilabel>, 
+          <guilabel>Split view</guilabel></term>
+        <listitem>
+          <para>
+            These options are common to GEGL-based filters. Please refer to 
+            <xref linkend="gimp-filters-common"/>.
+          </para>
+        </listitem>
+      </varlistentry>
+      
+      <varlistentry>
+        <term><guilabel>Iterations</guilabel></term>
+        <listitem>
+          <para>
+            Increasing Iterations increases blur.
+          </para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </sect3>
+  
+  <sect3>
+    <title>Examples</title>
+    <para>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="JPEG"
+            fileref="images/filters/examples/blur/mean_curvature-ex-1.jpg"/>
+        </imageobject>
+        <caption>
+          <para>
+            Original image
+          </para>
+        </caption>
+      </mediaobject>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="JPEG"
+            fileref="images/filters/examples/blur/mean_curvature-ex-2.jpg"/>
+        </imageobject>
+        <caption>
+          <para>
+            Iterations = 4
+          </para>
+        </caption>
+      </mediaobject>
+    </para>
+    <para>
+      Mean Curvature Blur can be used to denoise an image:
+      <figure>
+        <title>Mean Curvature Blur to denoise</title>
+        <mediaobject>
+          <imageobject>
+            <imagedata format="PNG"
+            fileref="images/filters/examples/enhance/noise-reduction-ex1.png"/>
+          </imageobject>
+          <caption>
+            <para>
+              Original image
+            </para>
+          </caption>
+        </mediaobject>
+        <mediaobject>
+          <imageobject>
+            <imagedata format="JPEG"
+          fileref="images/filters/examples/blur/mean_curvature-denoise.jpg"/>
+          </imageobject>
+          <caption>
+            <para>
+              Iterations = 9
+            </para>
+          </caption>
+        </mediaobject>
+      </figure>
+    </para>
+  </sect3>
+</sect2>
+