Hello there, Yesterday evening, when working on this http://bugzilla.gnome.org/show_bug.cgi?id=165645 , I've experienced some performance issues when using lossless jpeg rotation. For this, I use JpegUtils.Transform which itself use libjpegtran.
Here is some benchmarks of exiftran (same code as jpegtran) for rotating a 7Mpixels Jpeg image (file size: 3.18MB) $ time exiftran -9 IMG_0952.JPG -o out.jpg real 0m37.947s user 0m1.473s sys 0m26.873s That time correspond to the time f-spot need to rotate lossless. After googling around a bit this morning, I've found that you can speed up jpegtran with allowing it to use more memory. $ export JPEGMEM=64m $ time exiftran -9 IMG_0952.JPG -o out.jpg real 0m1.935s user 0m1.564s sys 0m0.242s For this image and on my system with only 1G of ram, I encounter better performances with JPEGMEM=64m than 128m, probably due to the time needed to allocate memory or sg like this. Now, I run f-spot like this: $ export JPEGMEM=64m $ f-spot And the lossless rotations in f-spot are automagically speeded by a factor of 10, at least. My question to the list: - Back in 98, when jpegtran was released, the default amount of memory was probably engouh. Now, with megapixels camera, we should probably compile libjpegtran with a superior default. What do you think of this, what's a good default value ? - With the great gap between entry level camera producing <200k files and the high-end Digital SLR, storing probably >10M files, and also to match with the user hardware configuration, could we foresee an runtime option in the preference dialog ? I'm waiting for your feedback. In the meantime, I'll try to see how to enhance the default memory value in libjpegtran Best regards, Stefan -- Stephane Delcroix [EMAIL PROTECTED] _______________________________________________ F-spot-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/f-spot-list
