[solang/help] help: more about histograms

[Florent Thévenet <fthevenet src gnome org>]

commit 11caa7ec5e34d3d0805edcadc658e2114ba1ba13
Author: Florent Thévenet <feuloren free fr>
Date:   Thu Mar 25 00:53:09 2010 +0100

    help: more about histograms

 help/C/export_CD.page       |    2 +-
 help/C/figures/modified.jpg |  Bin 0 -> 25229 bytes
 help/C/figures/normal.jpg   |  Bin 0 -> 28256 bytes
 help/C/figures/over.jpg     |  Bin 0 -> 25862 bytes
 help/C/figures/under.jpg    |  Bin 0 -> 24653 bytes
 help/C/histogram.page       |   42 ++++++++++++++++++++++++++++++++----------
 help/C/index.page           |    2 +-
 7 files changed, 34 insertions(+), 12 deletions(-)
---
diff --git a/help/C/export_CD.page b/help/C/export_CD.page
index 4a9672c..9adfdde 100644
--- a/help/C/export_CD.page
+++ b/help/C/export_CD.page
@@ -27,7 +27,7 @@
 	</item>
 	<item>
 	<p>Check <gui>Create an archive</gui> if you want your photos to be packed up in a compressed archive. Thanks to this function you can put more photos on the same CD but devices like DVD players won't be able to display your photos.
-	Otherwise your photos will be burned directly to the CD.</p>
+	Otherwise your photos will be burned directly onto the CD.</p>
 	</item>
 	<item>
 	<p>Choose <gui>Export</gui> to export the photos.</p>
diff --git a/help/C/figures/modified.jpg b/help/C/figures/modified.jpg
new file mode 100644
index 0000000..c788375
Binary files /dev/null and b/help/C/figures/modified.jpg differ
diff --git a/help/C/figures/normal.jpg b/help/C/figures/normal.jpg
new file mode 100644
index 0000000..9bb4b69
Binary files /dev/null and b/help/C/figures/normal.jpg differ
diff --git a/help/C/figures/over.jpg b/help/C/figures/over.jpg
new file mode 100644
index 0000000..458aab4
Binary files /dev/null and b/help/C/figures/over.jpg differ
diff --git a/help/C/figures/under.jpg b/help/C/figures/under.jpg
new file mode 100644
index 0000000..48229d4
Binary files /dev/null and b/help/C/figures/under.jpg differ
diff --git a/help/C/histogram.page b/help/C/histogram.page
index ba6e86b..6216508 100644
--- a/help/C/histogram.page
+++ b/help/C/histogram.page
@@ -60,30 +60,47 @@
 <p>Histograms are useful because they let you see if your photos are correctly exposed. Take the following examples.</p>
 <table frame="all" rules="rows cols" shade="rows">
     <tr>
-    <td><p>Photo normal</p></td>
+    <td>
+  <figure>
+    <media type="image" src="figures/normal.jpg" mime="image/jpg" style="right">
+      <p>A correctly exposed photo</p>
+    </media>
+  </figure>
+</td>
     <td><p>Histogram</p></td>
     </tr>
     <tr>
     <td><p>Correctly exposed photo</p></td>
-    <td></td>
+    <td><p>This is an example of a correctly exposed image with a "good" histogram. The smooth curve downwards ending in 255 shows that the subtle highlight detail in the clouds and waves is preserved. Likewise, the shadow area starts at 0 and builds up gradually. </p></td>
     </tr>
 
     <tr>
-    <td><p>Photo overexposed</p></td>
+    <td>
+  <figure>
+    <media type="image" src="figures/over.jpg" mime="image/jpg" style="right">
+      <p>An overexposed photo</p>
+    </media>
+  </figure>
+ </td>
     <td><p>Histogram</p></td>
     </tr>
     <tr>
     <td><p>Overexposed photo</p></td>
-    <td></td>
+    <td><p>The histogram indicates there are a lot of pixels with value 255 or close to 255, which is an indication of "clipped highlights". Subtle highlight detail in the clouds and waves is lost. There are also very few pixels in the shadow area.</p></td>
     </tr>
 
     <tr>
-    <td><p>Photo underexposed</p></td>
+    <td>
+  <figure>
+    <media type="image" src="figures/under.jpg" mime="image/jpg" style="right">
+      <p>An underexposed photo</p>
+    </media>
+  </figure></td>
     <td><p>Histogram</p></td>
     </tr>
     <tr>
     <td><p>Underexposed photo</p></td>
-    <td></td>
+    <td><p>The histogram indicates there are a lot of pixels with value 0 or close to 0, which is an indication of "clipped shadows". Some shadow detail is lost forever as explained in the dynamic range topic. Unless there is a lot of pure black in the image, there should not be that many pure black pixels. There are also very few pixels in the highlight area.</p></td>
     </tr>
 
     <tr>
@@ -92,7 +109,7 @@
     </tr>
     <tr>
     <td><p>Photo with too much contrast</p></td>
-    <td></td>
+    <td><p>This image has both clipped shadows and highlights. The dynamic range of the scene is larger than the dynamic range of the camera. The dinamic range is the capability of a camera to capture both shadow and highlights details.</p></td>
     </tr>
 
     <tr>
@@ -101,16 +118,21 @@
     </tr>
     <tr>
     <td><p>Photo with too low contrast</p></td>
-    <td></td>
+    <td><p>This image only contains midtones and lacks contrast, resulting in a hazy image.</p></td>
     </tr>
 
     <tr>
-    <td><p>Photo modified</p></td>
+    <td>
+  <figure>
+    <media type="image" src="figures/modified.jpg" mime="image/jpg" style="right">
+     <p>A photo with modified contrast</p>
+    </media>
+  </figure></td>
     <td><p>Histogram</p></td>
     </tr>
     <tr>
     <td><p>Photo with modified contrast</p></td>
-    <td></td>
+    <td><p>When "stretching" the above histogram via a Levels or Curves adjustment, the contrast of the image improves, but since the tones are redistributed over a wider tonal range, some tones are missing, as indicated in this "combed" histogram. Too much combing can lead to posterization.</p></td>
     </tr>
 </table>
 
diff --git a/help/C/index.page b/help/C/index.page
index 9359d83..ac58520 100644
--- a/help/C/index.page
+++ b/help/C/index.page
@@ -48,7 +48,7 @@
 		<title>Tips and Tricks</title>
 		<info>
 			<link type="topic" xref="keys"/>
-			<!--<link type="topic" xref="histogram"/>-->
+			<link type="topic" xref="histogram"/>
 		</info>
 	</section>