How to batch convert RAW images in several subfolders to DNG

Question

So I have 20 subfolders full of files in my main folder and have around 200 files in every subfolder. I've been trying to write a script to convert every picture in every subfolder to DNG. I have done some research and was able to batch convert images from the current folder. I've tried developping the idea to get it to work for subfolders but to no success. Here is the code I've written:

for D in 'find . -type d'; do for i in *.RW2; do sips -s format jpeg $i --out "${i%.*}.jpg"; cd ..; done; done;

Answer 1

The easiest and fastest way to do this is with GNU Parallel like this:

find . -iname \*rw2 -print0 | parallel -0 sips -s format jpeg --out {.}.jpg {}

because that will use all your CPU cores in parallel. But before you launch any commands you haven't tested, it is best to use the --dry-run option like this so that it shows you what it is going to do, but without actually doing anything:

find . -iname \*rw2 -print0 | parallel --dry-run -0 sips -s format jpeg --out {.}.jpg {}

Sample Output

sips -s format jpeg --out ./sub1/b.jpg ./sub1/b.rw2
sips -s format jpeg --out ./sub1/a.jpg ./sub1/a.RW2
sips -s format jpeg --out ./sub2/b.jpg ./sub2/b.rw2

If you like the way it looks, remove the --dry-run and run it again. Note that the -iname parameter means it is insensitive to upper/lower case, so it will work for ".RW2" and ".rw2".

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GNU Parallel is easily installed on macOS via homebrew with:

brew install parallel

It can also be installed without a package manager (like homebrew) because it is actually a Perl script and Macs come with Perl. So you can install by doing this in Terminal:

(wget pi.dk/3 -qO - ||  curl pi.dk/3/) | bash

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Your question seems confused as to whether you want DNG files like your title suggests, or JPEG files like your code suggests. My code generates JPEGs as it stands. If you want DNG output, you will need to install Adobe DNG Converter, and then run:

find . -iname \*rw2 -print0 | parallel --dry-run -0 \"/Applications/Adobe DNG Converter.app/Contents/MacOS/Adobe DNG Converter\" 

There are some other options you can append to the end of the above command:

• -e will embed the original RW2 file in the DNG
• -u will create the DNG file uncompressed
• -fl will add fast load information to the DNG

DNG Converter seems happy enough to run multiple instances in parallel, but I did not test with thousands of files. If you run into issues, just run one job at a time by changing to parallel -j 1 ...

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Adobe DNG Converter is easily installed under macOS using homebrew as follows:

brew install caskroom/cask/adobe-dng-converter