I am sure that someone will come along with a more technical answer, however my simple view on this is with variations on saving / exporting.
If you export to lossy format jpeg / webp you will get a small file size but lose the data.
Some file size comparisons:
00-from-camera.jpg 7.0 MB - 96 compression
01-save.xcf 51.5 MB
02-save.xcf.gz 40 MB
03-save-better.xcf 33.6 MB
The original (00) is a jpeg and small - open in Gimp and it shows as 167 MB Any extra layers adds to that, however without any editing. A Save in lossless xcf format with options .
A straight Save (01) is large, you can get a smaller file size with secondary compression, a .xcf.gz (02) and smaller again using Gimp 3 "better compression" option. All those are lossless.
With editing and adding layers / masks / groups will add to the saved file size, however it is worth using Gimp 3 layer effects (fx) where it seems to add only a small overhead and are still editable. This one is better-with-effects.xcf is 40 MB compared to 33.6 MB. Obviously all depends on the image and editing, add text for example is adding layers and increased file size.
Quote:...snip.... In definitive I want to keep the original photo, the exported one and all that allowed to obtain the exported result.
If you export to lossy format jpeg / webp you will get a small file size but lose the data.
Some file size comparisons:
00-from-camera.jpg 7.0 MB - 96 compression
01-save.xcf 51.5 MB
02-save.xcf.gz 40 MB
03-save-better.xcf 33.6 MB
The original (00) is a jpeg and small - open in Gimp and it shows as 167 MB Any extra layers adds to that, however without any editing. A Save in lossless xcf format with options .
A straight Save (01) is large, you can get a smaller file size with secondary compression, a .xcf.gz (02) and smaller again using Gimp 3 "better compression" option. All those are lossless.
With editing and adding layers / masks / groups will add to the saved file size, however it is worth using Gimp 3 layer effects (fx) where it seems to add only a small overhead and are still editable. This one is better-with-effects.xcf is 40 MB compared to 33.6 MB. Obviously all depends on the image and editing, add text for example is adding layers and increased file size.