[Digikam-users] slow auto-rotate images when downloading from camera

Tom Malfrere tom.malfrere at telenet.be
Tue Aug 31 11:16:41 BST 2010


I have a Canon 550D camera which takes 18Mpixel images.

I noticed that when I download the image from my camera there is a huge 
speed difference between photo's in landscape and photo in portrait.
A landscape take about 0,5s to download while a portrait photo takes about 3s.
300 images at 3s a piece is 900s. 
That's a long wait while it would normally only take 150s...

The problem is that the images in portrait are auto-rotated based on the 
EXIF info. 
I have no problem with the rotation but it just takes to much time.

I had the following idea:
1) Thread 1 downloads all the image from the camera to the PC as fast as 
2) Thread 2 checks the downloaded images on disk to see if they need to 
be auto-rotated based on the EXIF info. This second thread spawns a worker 
thread for every image that must be rotated. The worker thread does the 
actual rotating. Maybe the number of simultaneous worker threads should 
be limited.

I'm posting this message here to know what other people think about this,
so let me know and post a message back.


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