Re: JPEG thumbnailing latency
- From: "Dr. Michael J. Chudobiak" <mjc avtechpulse com>
- To: Christian Kirbach <christian kirbach googlemail com>
- Cc: nautilus-list gnome org, Mike Rooney <mrooney gmail com>
- Subject: Re: JPEG thumbnailing latency
- Date: Tue, 10 Jun 2008 08:18:26 -0400
Christian Kirbach wrote:
Thumbnailing is a slow process (especially for raw files) since it is
compute and io intensive (i.e., lots of matrix algebra + large files).
That is not neccessarily true. I know that the Nikon RAW file format
also stores jpeg encoded preview images ('thumbnails')
But I don't know whether ufraw is used by nautilus with this option
Yes, on my Fedora system, ufraw is called as a thumbnailer script with
/usr/bin/ufraw-batch --embedded-image --out-type=png --size=%s %i
However, thumbnailing of ordinary jpeg and tiff images is still too slow
and highly memory intensive, mostly because the gtk scaling routines
don't work well for large scaling factors (typically required for
digital photos). This will slow down the embedded thumbnail -> system
thumbnail process too.
The gtk scaling routines really need some love from an algebra guru.
The tiff pixbuf loader could really use some optimization (e.g.,
skipping strips in strip-based images to speed up thumbnailing). Maybe
the png loader could use similar tricks.
Side note: yes, some jpeg images also have embedded thumbnails. However,
many apps forget to modify this thumbnail if the main image is modified,
making the embedded thumbnail highly unreliable...
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