(07-27-2021, 07:54 AM)snowforest Wrote: For the last item, filing to copyright office for my book, which includes the images I made is also a good protection right? Because most my images are not very complicated ones I draw myself using librecad etc... and cropping doesn't mean much (someone can add the lines to the sides of the image)
If you have the LibreCAD project from which you can re-export the image then you are good.
(07-27-2021, 07:54 AM)snowforest Wrote: And about the thing you mention about layers, so I should put empty layer onto my image and save like that even if it is redundant?
Sevres to purposes, but if your Gimp image has several non-trivial layers, then you can show that you can makes small alterations easily (something that a copyright thief won't be able to do).
(07-27-2021, 07:54 AM)snowforest Wrote: also does it help to put copyright as a Jpeg "comment", as you suggested or that means nothing?
Not that much, but at least it normally survives the erasure of other metadata.
All in all, don't overthink it. If your images are a few lines they can be redone... Their added value may be in the idea they carry (a novel way to explain something, for instance) and there is no copyright for this.