Post-op file size reduction, mandatory tags

[mazeckenrode]

This is more curiosity than anything else, but I've noticed at least a few times now that files I've used ExifTool to add metadata to, and/or add to existing metadata in, have become smaller rather than larger files following the operation, even despite the fact that ExifTool is adding additional tags not specifically called for in my operation. Why would they become noticeably smaller?

Also, I understand that at least some (maybe all, I didn't cross-check every one) of the added tags are considered "mandatory" according to EXIF specs, but on the other hand, there are some EXIF tags listed as mandatory that were NOT added to the file in this case (InteropVersion, Compression, ExifImageWidth, ExifImageHeight).

Attached: "Meta+ Size.7z" (2,709)

Contents:

"Meta+ Size\"
  "Meta.png" (4,049) [1 x 1 x 1]
  "Meta+.png" (3,130) [1 x 1 x 1]

[StarGeek]

This is more curiosity than anything else, but I've noticed at least a few times now that files I've used ExifTool to add metadata to, and/or add to existing metadata in, have become smaller rather than larger files following the operation, even despite the fact that ExifTool is adding additional tags not specifically called for in my operation. Why would they become noticeably smaller?

See FAQ #13

[mazeckenrode]

See FAQ #13

Ah, managed to miss or forget about that in the FAQ. Sorry.