img to 000 conversion is almost certainly related to recovery of disk images done using ISOBuster, which creates sequenced disk image files from RAW recovery of data from various disk image formats. You do not convert to this format manually, but it's done as part of the recovery procedure.
But 'img' is often short for just pretty much of any picture (image), so it might very well be possible that it might be related to conversion of graphics files as well. Quite often .000 files are just pictures in standard JPEG/PNG format with their suffix changed to create a numbered sequence.
Updated: November 2, 2023