storing size of project file (previews?)

[ChoJin]

I'm not sure whether it's a bug or a wishlist

I've just noticed that the storing size of a preview, when saving a project with images, seems to be the same than the full image.

my current project has an image stored compressed as roughly 700M and I have 13 (tiny) previews on that image.
Given the saved project data, I can see 14 files with a size of roughly 700M. So it looks like it's somehow storing the preview as a full sized image, yielding to a very big project storage.

I'm surprised, I would have expected a preview to take almost no space to store (just the coordinates), am I missing something?

[ChoJin]

maybe that's not the size of the previews, I copied the preview to a greyscale version of the image (hence smaller) and I can still see the same amount of 700M files. So I dont know why the project jumped from 2G to 11G.

[RickS]

The 700M files are probably snapshots of your image.  PI saves a copy every time you change an image so that you can undo an arbitrary number of processing steps.