Sandman
In article <1bhp1a9t7296qfn858npvei673csf7sagj@4ax.com>, Eric Stevens wrote:

Eric Stevens
And I have pointed out that you cannot reverse a change which has not actually been made. Even if it is reversible, you can't reverse something before you have done it.

nospam
the change *has* been made, just not to the pixels themselves.

Eric Stevens
And to what has the change been made?

Sandman
To the pixels. nospam is incorrect here. All LR adjustments are applied to a preview file and saved to disk.

nospam
the changes are rendered on the fly and may be cached to disk (which is the preview file you're talking about). the latter is optional.

Sandman
It's not optional. All images in LR are always rendered as previews. They are kept inside your LR library.

Eric Stevens
That's true, but all the preview images I have looked at are between about 50% and 20% of the size of the original.

Sandman
This is false.

Eric Stevens
They clearly can't contain as much data or be reconstructed to form a final export image.

Sandman
Depends on whether or not you're exporting a full resolution image, Eric. Just as I said.

Eric Stevens
In otherwords, what you have in these files is not an edited version of the original image.

Sandman
Incorrect. Otherwise they wouldn't be previews.