2008.04.16 13:26 "[Tiff] efficient thumbnailing", by Dr. Michael J. Chudobiak

Hi all,

Is there an efficient way to generate thumbnails from tiff files?

Currently, when the gnome/gtk+ gdk-pixbuf tiff loader wants to generate a thumbnail of a tiff file, it loads the entire image, and then scales it. (See http://svn.gnome.org/viewvc/gtk%2B/trunk/gdk-pixbuf/io-tiff.c?view=markup).

This uses a lot of memory, and the gtk+ scale-down routines are not very good (http://bugzilla.gnome.org/show_bug.cgi?id=80925).

Is there a way in libtiff to do some scale-while-loading, or prescaling, to reduce memory usage and speed things up? (Or could it be added to libtiff?)

The jpeg loader uses some fast-scaling trickery to scale down by a factor of 2, 4, or 8 first (http://sylvana.net/jpegcrop/djpeg) - I was wondering if there is a tiff equivalent.

Suggestions and pointers to existing code appreciated!

- Mike