I started to use my Sony a7 III to produce uncompressed raw files. Since then I have done some testing and I’d like to “convert” all of my uncompressed ARW files to be compressed. Do you have any idea how to do that?
Don’t think that’s possible. In Sony’s world lossless raw compression (which Canon has has had for as long as I can remember) is a reason for you to buy a new camera. Lossless DNG compression works well though. 
Whatever you do, please don’t discard the original raw file!
For photos you already took , just use 7z to compress them, if you want them to take up less space.
Maybe you can use Adobe dng converter to create a lossy, small resolution DNG to keep along with the 7z / rar / bz2 / xz compressed file . That way you have something to view and toy around with and index with all metadata and stuff…
But like others said , ALWAYS keep your original arw. I’ve read more than enough people who converted entire catalogs to DNG, and then regretted it later.
1 Like
Thank you for the answers. I live on Ubuntu, so I just thought something can exists on Linux world… similar like ffmpeg what can convert images without GUI.