[gimp-help] Small update in concepts

[Julien Hardlin <jhardlin src gnome org>]

commit c125a38bc59749a9283a8839754439d9b478923c
Author: Julien Hardelin <jhardlin orange fr>
Date:   Mon Apr 13 07:31:18 2020 +0200

    Small update in concepts

 images/C/using/file-open-dialog.png | Bin 20634 -> 88928 bytes
 src/concepts/image-types.xml        |  22 +++++++---------------
 2 files changed, 7 insertions(+), 15 deletions(-)
---
diff --git a/images/C/using/file-open-dialog.png b/images/C/using/file-open-dialog.png
index bb05be55d..ea4ce3b71 100644
Binary files a/images/C/using/file-open-dialog.png and b/images/C/using/file-open-dialog.png differ
diff --git a/src/concepts/image-types.xml b/src/concepts/image-types.xml
index 063bd69a5..06f5dd0e8 100644
--- a/src/concepts/image-types.xml
+++ b/src/concepts/image-types.xml
@@ -2,11 +2,7 @@
 <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
                        "http://www.docbook.org/xml/4.3/docbookx.dtd";>
 <!-- section history
-  2009-02-19 j.h:revised for v2.6. No change
-  2007-03-26 reviewed Korean translation by Dust
-  2006-08-28 added norwegian translation by KoSt
-  2006-05-02 added Korean translation by Dust
-  2005-12-18 reviewed and added rewrote de image explenation by lexa
+  2020-04-12 Update to 2.10.18
 -->
 <sect1 id="gimp-concepts-image-types">
   <title>Image Types</title>
@@ -121,15 +117,10 @@
     </mediaobject>
   </figure>
   <para>
-    In <acronym>GIMP</acronym>, every color channel, including the alpha
-    channel, has a range
-    of possible values from 0 to 255; in computing terminology, a depth of 8
-    bits. Some digital cameras can produce image files with a depth of 16
-    bits per color channel. <acronym>GIMP</acronym> cannot load such a file
-    without losing
-    resolution. In most cases the effects are too subtle to be detected by
-    the human eye, but in some cases, mainly where there are large areas
-    with slowly varying color gradients, the difference may be perceptible.
+    In <acronym>GIMP</acronym>, in every color channel, including the alpha
+    channel, possible values have a range depending on the image precision:
+    0 to 255 for a color depth of 8 bits. <acronym>GIMP</acronym> can now load 
+    16 and 32 bits images, and this range can be much larger.
   </para>
   <figure>
     <title>Example of an image with alpha channel</title>
@@ -186,7 +177,8 @@
   <para>
     The third type, <emphasis>indexed</emphasis>
     images, is a bit more complicated to understand. In an indexed image,
-    only a limited set of discrete colors are used, usually 256 or less.
+    only a limited set of discrete colors are used, usually 256 or less (so, 
+    this indexed mode can be applied only to images with 8 bits precision).
     These colors form the <quote>colormap</quote> of the image, and each
     point in the image is assigned a color from the colormap. Indexed images
     have the advantage that they can be represented inside a computer in a