Hello all,
Following an earlier thread on this list, I would like to propose a
minor update to the Thumbnail Managing Standard. A patch is attached
against the HTML version. (I contacted Olivier Sessink, but he indicated
that there was probably no valid up-to-date docbook source for the
original HTML files.)
The proposed changes are meant to be uncontroversial, and are meant to
codify existing best practices. The basic changes are:
1) Indicate that all cache reads and writes should be skipped for
non-readable images (as discussed earlier on this list).
2) Indicate that image metadata, including orientation tags, should be
respected. (The libgnomeui thumbnailer and gthumb do this for sure;
other programs may differ.)
3) Some minor spelling corrections.
A patch is attached for discussion. A patched version is viewable here:
http://www.avtechpulse.com/opensource/spec-new/index.html
- Mike
diff -bur spec-old/creation.html spec-new/creation.html
--- spec-old/creation.html 2008-03-08 05:08:16.000000000 -0500
+++ spec-new/creation.html 2008-04-12 13:09:00.000000000 -0400
@@ -79,7 +79,7 @@
CLASS="SECT2"
><A
NAME="AEN139"
->Fileformat</A
+>File format</A
></H2
><P
> The image format for thumbnails is the <A
@@ -93,7 +93,16 @@
possible quality when creating the thumbnail. The exact meaning of this
is left to the specific program but it should consider applying
antialising.</P
-></DIV
+><P
+> If the original file contains metadata affecting the interpretation
+ of the image, it should be respected as much as possible. In particular,
+ metadata specifying the orientation of the original image data should
+ always be respected. The image data should be transformed as specified by the
+ metadata before generating the thumbnail. JPEG files commonly have Exif
+ orientation tags. TIFF files may also have Exif orientation tags, although
+ this is less common. It is less critical, but still desirable, to respect
+ other image metadata, such as white balance information.</P
+</DIV
><DIV
CLASS="SECT2"
><H2
diff -bur spec-old/delete.html spec-new/delete.html
--- spec-old/delete.html 2008-03-08 05:08:20.000000000 -0500
+++ spec-new/delete.html 2008-04-12 13:15:15.000000000 -0400
@@ -84,13 +84,13 @@
TYPE="1"
><LI
><P
->If a filemanger is aware of this standard and deletes a file it
+>If a file manager is aware of this standard and deletes a file it
could take care of deleting the thumbnail too.</P
></LI
><LI
><P
>A daemon runs in the background which cleans up the cache in certain
- intervalls.</P
+ intervals.</P
></LI
><LI
><P
diff -bur spec-old/failures.html spec-new/failures.html
--- spec-old/failures.html 2008-03-08 05:08:28.000000000 -0500
+++ spec-new/failures.html 2008-04-12 13:14:02.000000000 -0400
@@ -117,7 +117,7 @@
>~/.thumbnails/fail/nautilus-1.0</SAMP
>).</P
><P
-> For every thumbnail generation failure the program creates an empty
+> For every thumbnail generation failure of a readable image, the program creates an empty
PNG file. If it's possible to obtain some additional information from
the image (see <A
HREF="creation.html#ADDINFOS"
diff -bur spec-old/index.html spec-new/index.html
--- spec-old/index.html 2008-03-08 05:08:32.000000000 -0500
+++ spec-new/index.html 2008-04-12 13:19:36.000000000 -0400
@@ -78,7 +78,7 @@
></DIV
><SPAN
CLASS="RELEASEINFO"
->Version 0.7.0<BR></SPAN
+>Version 0.7.1<BR></SPAN
><HR></DIV
><DIV
CLASS="SECT1"
@@ -93,6 +93,22 @@
><UL
><LI
><P
+>April 2008, Version 0.7.1</P
+><P
+></P
+><UL
+><LI
+><P
+>Indicate that image metadata, including orientation tags, should be respected.</P
+></LI
+><LI
+><P
+>Indicate that all cache reads and writes should be skipped for non-readable images.</P
+></LI
+></UL
+></LI
+><LI
+><P
>September 2004, Version 0.7.0</P
><P
></P
diff -bur spec-old/thumbsave.html spec-new/thumbsave.html
--- spec-old/thumbsave.html 2008-03-08 05:08:58.000000000 -0500
+++ spec-new/thumbsave.html 2008-04-12 13:13:34.000000000 -0400
@@ -146,8 +146,12 @@
>Permissions</A
></H2
><P
->A few words regarding permissions:
- All the directories including the ~/.thumbnails directory must have set
+> The program should first check to ensure that the original image file is
+ readable. If it is not, the program should not attempt to read a thumbnail
+ from the cache, and it should not save any information in the cache
+ (including "failed" thumbnails).</P
+><P
+> All the directories including the ~/.thumbnails directory must have set
their permissions to 700 (this means only the owner has read, write and
execute permissions, see "man chmod" for details). Similar, all the files
in the thumbnail directories should have set their permissions to 600. This
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