Convert DDS to PNG using linux command line

Does anyone know a good way to batch-convert a bunch of PNGs into JPGs in linux? (I'm using Ubuntu).

A png2jpg binary that I could just drop into a shell script would be ideal.

Your best bet would be to use Imagemagick

I am not an expert in the actual usage, but I know you can pretty much do anything image related with this!

An example is:

convert image.png image.jpg

and it will keep the original as well as creating the converted image. As for batch. I think you need to use the Mogrify tool (from the same command line when in imagemagick). Keep in mind that this overwrites the old images.

The command is:

mogrify -format jpg *.png  

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:

for img in *.png; do
    filename=${img%.*}
    convert "$filename.png" "$filename.jpg"
done

The actual "png2jpg" command you are looking for is in reality split into two commands called pngtopnm and cjpeg, and they are part of the netpbm and libjpeg-progs packages, respectively.

png2pnm foo.png | cjpeg > foo.jpeg

I have a couple more solutions.

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

for i in *.png ; do convert "$i" "${i%.*}.jpg" ; done

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

ls -1 *.png | xargs -n 1 bash -c 'echo "$0" "${0%.*}.jpg"'

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).

parallel convert '{}' '{.}.jpg' ::: *.png

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.

parallel -j 3 convert '{}' '{.}.jpg' ::: *.png

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

parallel --eta convert '{}' '{.}.jpg' ::: *.png

The final command that I use looks like this for refrence. I use ls rather than parallel's syntax for who-knows-what reason.

ls -1 *.png | parallel -j 3 --eta convert '{}' '{.}.jpg'

For batch processing:

for img in *.png; do
  convert "$img" "$img.jpg"
done

You will end up with file names like image1.png.jpg though.

This will work in bash, and maybe bourne. I don't know about other shells, but the only difference would likely be the loop syntax.

my quick solution for i in $(ls | grep .png); do convert $i $(echo $i.jpg | sed s/.png//g); done