Question

I have a folder of images over 4MB – let’s call this folder dsc_big/. I’d like to use convert -define jpeg:extent=2MB to convert them to under 2MB and copy dsc_big/* to a folder dsc_small/ that already exists.

I tried convert dsc_big/* -define jpeg:extent=2MB dsc_small/ but that produces images called -0, -1, and so on.

What do I do?

Answer 1

convert is designed to handle a single input file as far as I can tell, although I have to admit I don’t understand the output you’re getting. mogrify is better suited for batch processing in the following style:

mogrify -path ../dsc_small -define jpeg:extent=2MB dsc_big/*

But honestly I consider it dangerous for general usage (it’ll overwrite the original images if you forget that -path) so I always use convert coupled with a for loop for this:

for file in dsc_big/*; do convert $file -define jpeg:extent=2MB dsc_small/`basename $file`; done

The basename call isn’t necessary if you’re processing files in the current directory.