A Standard for Thumbnailers

[Stanislav Brabec]

Benedikt Meurer wrote:
> Steve Frécinaux wrote:
> >> BTW: I fail to see the problem here. How often do people regenerate
> >> thumbnails that +1 or 2 seconds for 40 JPEGs makes a difference?
> > 
> > It's important because it gives an impression of slowness and
> > unresponsiveness. And you rarely generate them, but you import pictures
> > from digital cameras rather often.
> 
> Here the I/O is definitely the limiting factor from my experience.
> Accessing data on digital cameras is very slow with the models I've tested.

No, for digital cameras the limiting factor is the stupidity of the
thumbnailer.

Small jpeg-EXIF-embedded thumbnail is most often stored in first few
blocks of the image. You can create thumbnail much faster than you can
load the image.

Mid-size jpeg thumbnail (typically 640x480) is typically stored in last
few blocks of the image and you need only few additional seeks to find
exact start point. You can again create thumbnail faster than to load
image.

You can try to compare my dcraw-thumbnailer with Nautilus jpeg
thumbnailer to see the difference:
http://www.penguin.cz/~utx/gnome-dcraw
Note that this page also contain "classical" thumbnailer, which reads
the whole file and scales it down by its own.

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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