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Batch converting PNG to JPG with convert from the ImageMagick suite

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melodie:
Hi,

All is here:
http://superuser.com/questions/71028/batch-converting-png-to-jpg-in-linux


--- Citer --- 10 down vote

The convert command found on many Linux distributions is installed as part of the ImageMagick suite. Here's the bash code to run convert on all PNG files in a directory and avoid that double extension problem:


--- Code: ---for img in *.png; do
    filename=${img%.*}
    convert "$filename.png" "$filename.jpg"
done
--- Fin du code ---


--- Fin de citation ---

This is the one I just used, I ended with both png and jpg files in the same directory, which was the perfect result.



--- Citer ---I have a couple more solutions.

The simplest solution is like most already posted. A simple bash for loop.


--- Code: ---for i in *.png ; do convert "$i" "${i%.*}.jpg" ; done
--- Fin du code ---

For some reason I tend to avoid loops in bash so here is a more unixy xargs approach, using bash for the name-mangling.


--- Code: ---ls -1 *.png | xargs -n 1 bash -c 'convert "$0" "${0%.*}.jpg"'
--- Fin du code ---

The one I use. It uses GNU Parallel to run multiple jobs at once, giving you a performance boost. It is installed by default on many systems and is almost definitely in your repo (it is a good program to have around).


--- Code: ---ls -1 *.png | parallel convert '{}' '{.}.jpg'
--- Fin du code ---

The number of jobs defaults to the number of processes you have. I found better CPU usage using 3 jobs on my dual-core system.


--- Code: ---ls -1 *.png | parallel -j 3 convert '{}' '{.}.jpg'
--- Fin du code ---

And if you want some stats (an ETA, jobs completed, average time per job...)


--- Code: ---ls -1 *.png | parallel --eta convert '{}' '{.}.jpg'
--- Fin du code ---

There is also an alternative syntax if you are using GNU Parallel.


--- Code: ---parallel convert '{}' '{.}.jpg' ::: *.png
--- Fin du code ---

And a similar syntax for some other versions (including debian).


--- Code: ---parallel convert '{}' '{.}.jpg' -- *.png
--- Fin du code ---


--- Fin de citation ---

More on the above linked page.

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