- GC adds generates embedded thumbnails (Thumbnail IFD in addition to IFD0) for files that had no EXIF, but
- does NOT add embedded thumbnails for files that had EXIF (IFD0, Exif IFD) that were generated with GC with store exif preview disabled
How to make editor rotations to also be lossless?
My settings (the ones I think might be relevant, but I'm not familiar with all of them):
- Browser ⟶ Edit ⟶ JPEG ⟶Rotate always lossless (may add margins to the image)
- Browser ⟶ General ⟶ Thumbnails Generation
- ⟶ Fast (use only available icons)
- ⟶ (disabled) Always recreate preview
- ⟶ (disabled) Always recreate preview of JPEGs,...
- ⟶ (disabled) Use EXIF Preview...
- Browser ⟶ Thumbnails & Icons ⟶ Thumbnails
- ⟶ (disabled) Always recreate JPEG previews
However, if I rotate a jpeg that has no EXIF (empty Exif tab in the preview area) in the Viewer, embedded thumbnails do get generated, so I get two EXIF fields (Thumbnail IFD in addition to IFD0)
But then if instead of rotating I export the same file within GC to another jpeg (but disable store exif preview in the additional options) and then rotate this newly generated file (now it has two Exif fields: IFD0 and empty Exif IFD), I get no thumbnails.
I've also noticed that when I open the original noexif file in GC for editing and rotate it with the same shortcut there and then save, I don't get any Exif fields, not even IFD0
After enabling "Show options dialog" in Open ⟶ Image formats for JPEG I see that saving after rotation shows up this dialog, so I assume the save operation in not lossless, but a complete recompression. Is there a way to also force lossless rotation in the Editor?
Finally, how to make sure that lossless rotation never generates embedded thubnails?
Side question: is there an option to run a batch deletion of any existing embedded thumbnails? Or even to auto-delete them while browsing files?