[gimp-web/gimp-web-static] Ported Selective_Gaussian_Blur

From: Pat David <patdavid src gnome org>
To: commits-list gnome org
Cc:
Subject: [gimp-web/gimp-web-static] Ported Selective_Gaussian_Blur
Date: Fri, 25 Sep 2015 20:03:01 +0000 (UTC)
commit 87d71f10b3e0a874c5d545e720b98b5b3ff52be5
Author: Pat David <patdavid gmail com>
Date:   Fri Sep 25 15:02:53 2015 -0500

    Ported Selective_Gaussian_Blur

 content/about/meta/file-list.md                    |    2 +-
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 .../tutorials/Selective_Gaussian_Blur/after.jpg    |  Bin 0 -> 106431 bytes
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 .../tutorials/Selective_Gaussian_Blur/before.jpg   |  Bin 0 -> 123187 bytes
 content/tutorials/Selective_Gaussian_Blur/index.md |   85 ++++++++++++++++++++
 .../tutorials/Selective_Gaussian_Blur/org_sm.jpg   |  Bin 0 -> 40782 bytes
 19 files changed, 86 insertions(+), 1 deletions(-)
---
diff --git a/content/about/meta/file-list.md b/content/about/meta/file-list.md
index 3b05fab..1c9fe51 100644
--- a/content/about/meta/file-list.md
+++ b/content/about/meta/file-list.md
@@ -205,7 +205,7 @@ The main page links go to legacy WGO, the link icon (if there) will go to the po
 <del><http://www.gimp.org/tutorials/Red_Eye_Removal/index.html></del> [<i class="fa 
fa-link"></i>]({filename}../../tutorials/Red_Eye_Removal/index.md)  
 <del><http://www.gimp.org/tutorials/Reducing_CCD_Noise/index.html></del> [<i class="fa 
fa-link"></i>]({filename}../../tutorials/Reducing_CCD_Noise/index.md)  
 <del><http://www.gimp.org/tutorials/Selective_Color/index.html></del> [<i class="fa 
fa-link"></i>]({filename}../../tutorials/Selective_Color/index.md)  
-<http://www.gimp.org/tutorials/Selective_Gaussian_Blur/index.html>  
+<del><http://www.gimp.org/tutorials/Selective_Gaussian_Blur/index.html></del> [<i class="fa 
fa-link"></i>]({filename}../../tutorials/Selective_Color/index.md)  
 <http://www.gimp.org/tutorials/Sepia_Toning/index.html>  
 <http://www.gimp.org/tutorials/Simple_Animations/index.html>  
 <http://www.gimp.org/tutorials/Sketch_Effect/index.html>  
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diff --git a/content/tutorials/Selective_Gaussian_Blur/index.md 
b/content/tutorials/Selective_Gaussian_Blur/index.md
new file mode 100644
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--- /dev/null
+++ b/content/tutorials/Selective_Gaussian_Blur/index.md
@@ -0,0 +1,85 @@
+Title: Noise Removal with Selective Gaussian blur
+Date: 2002
+Modified: 2015-09-25T13:33:27-05:00
+Author: Atte André Jensen
+
+
+<small>
+Text and images Copyright (C) 2002 [Atte André Jensen](mailto:atteNOSPAM wanadoo nl) and may not be used 
without permission of the author.
+</small>
+
+## Intention
+
+Digital cameras often have quite some noise in their pictures. Some are worse than others, but it's there. 
Here I'll show you a way to get rid of that noise using the selective Gaussian blur filter.
+
+The basic idea behind selective Gaussian blur is that areas in the photo with contrast below a certain 
threshold gets blurred. You could think of it like the opposite of unsharpen mask (that sharpens everything 
with contrast above a certain threshold.
+
+## Step 1
+
+<figure>
+<img src="01.png" alt="01.png"/> <img src="02.jpg" alt="02.jpg"/>
+</figure>
+
+<figure>
+<img src="03.png" alt="03.png"/> <img src="04.jpg" alt="04.jpg"/>
+</figure>
+
+Since the selective Gaussian blur filter doesn't have a preview and is quite heavy to compute (proportional 
with blur radius), it's easier to only work on a cropped version of you picture. Select the crop tool from 
the tool box, draw a selection and click "crop".
+
+For best results, this should a part where there's some noise you want to remove and some detail you want to 
preserve.
+
+## Step 2
+
+<figure>
+<img src="05.jpg" alt="05.jpg"/>
+</figure>
+
+The next thing is to experiment with different combinations of the settings ("blur radius" and "maximum 
delta") in the selective Gaussian blur filter.
+
+Normally I find that both settings should be between 5 and 10, where low numbers has less effect and higher 
numbers more, but this is very depending on the camera. In short, maximum delta should be just high enough 
for the filter to kick in on the noise and blur radius should be just high enough to remove it (actually 
blend it with neighboring areas).
+
+<figure>
+<img src="06.png" alt="06.png"/> <img src="07.jpg" alt="07.jpg"/>
+</figure>
+
+<figure>
+<img src="08.png" alt="08.png"/> <img src="09.jpg" alt="09.jpg"/>
+</figure>
+
+<figure>
+<img src="15.png" alt="15.png"/> <img src="00.jpg" alt="00.jpg"/>
+</figure>
+
+For a more in depth explanation of what the settings do see 
[http://www.ftgimp.com/help/C/filters/sel_gauss.html](http://www.ftgimp.com/help/C/filters/sel_gauss.html).
+
+After playing with the settings a bit I liked the clean look of a blur radius of 10 and maximum delta of 
10\. Then I checked what those settings looked like on another crop (which is always a good idea to do), I 
decided that it was on the very edge, and maybe even too much. There was too much loss of detail in the hair.
+
+<figure>
+<img src="13.jpg" alt="13.jpg"/><br/>
+<img src="15.png" alt="15.png"/> <img src="16.jpg" alt="16.jpg"/>
+</figure>
+
+An option would have been to back off a bit and use settings around blur radius 7 and maximum delta 6, but 
then again the only offending area was the hair. I finally decided to go with settings of 8/7.
+
+You'll often find yourself in these arguments with yourself over when it's too much and when it's too 
little. All I can say is that you develop a feel for it, and I'm still not finished developing that feel. In 
any case, it's good to know that the first things that start to look funny are often faces and hair.
+
+## The result
+
+<figure>
+<img src="org_sm.jpg" alt="org_sm.jpg"/>
+</figure>
+
+<figure>
+<img src="after_sm.jpg" alt="after_sm.jpg"/>
+</figure>
+
+After 8 minutes my AMD-K6 300 running Linux finished the process, and I got the following (note they are 
resized to 640x480 from 1280x960, you can get the larger files at the bottom of this page):
+
+**First image**: Before.  
+**Last image**: After (blur radius:8, maximum delta:7).
+
+## Files
+
+[Before, 1280x960, JPEG (120 Kb)](before.jpg)  
+[After, 1280x960, JPEG (104 Kb)](after.jpg)
+
diff --git a/content/tutorials/Selective_Gaussian_Blur/org_sm.jpg 
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