[Digikam-devel] extragear/graphics/digikam/kioslave

Gilles Caulier caulier.gilles at free.fr
Fri Jun 30 15:42:30 BST 2006

SVN commit 556526 by cgilles:

digikam from trunk : thumbnail KIO-slave use now the IPTC preview image to render thumbs on album view (if exist of course).

This way is very fast. If you take a large RAW file and convert it to a new png in 16 bits color depth, an IPTC preview tag will be created. This one will be used instead the whole image !

For example : I take a MRW RAW file from my Dynax 5D (3000x2000 pixels), and i convert it to a new 16 bits PNG file using editor. The size of the target PNG file is around 27Mb. If i take the whole image, thumb rendering thumb take 3-5 seconds on my Laptop PIII-650Mhz. Using IPTC preview tag instead, it take 300-500 mili-seconds !

Note : IPTC preview tag embed a 800x600 JPEG image... This tag is always created when a new image is saved in digiKam editor

CCMAIL: digikam-devel at kde.org

 M  +10 -0     digikamthumbnail.cpp  

--- trunk/extragear/graphics/digikam/kioslave/digikamthumbnail.cpp #556525:556526
@@ -246,6 +246,16 @@
     if (!fileInfo.exists())
         return false;
+    // Try to use embeded preview image from metadata.    
+    DMetadata metadata(path);
+    if (metadata.getImagePreview(image))
+    {
+        kdDebug() << "Use Exif/Iptc preview extraction. Size of image: " 
+                  << image.width() << "x" << image.height() << endl;
+        return true;
+    }
+    // Else, use the right way depending of image file extension.
     QString ext = fileInfo.extension().upper();
     if (ext == QString("JPEG") || ext == QString("JPG"))

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