nospam
In article <qogm1a5hikba6q578as28s1el6u3l7v9se@4ax.com>, Eric Stevens <eric.stevens@sum.co.nz>wrote:

Eric Stevens
As nospam has so often told us, Lightroom (and other software using side car files) do not actually change the file being edited until it is in the process of being exported. In most case, all you see on the screen is a simplified simulacrum of what the edited file will look like, when the editing instructions are executed.

Once you export the file - that's it. You cannot reverse the changes. All you can do is edit the original all over again but this time slightly differently.

nospam
which means the changes are reversible.

Eric Stevens
Now it's interesting that Lightroom does incorporate something a little bit like the reversible process that Floyd was talking about but neither nospam or Savageduck seem to realise the fact. See http://tinyurl.com/p5sus42 From blur to sharpness on the one slider. But this is not actually a reversible process: it's a change in the instruction to the final edit which will only be executed when the image is exported.

nospam
not only do i realize it but that's what i've been saying all along.

you are *so* confused.

Eric Stevens
I do not know the type of sharpening used by Lightroom or whether or not it is truly reversible. If it uses HPS then it is possible to take a sharpened exported image and then reprocess it using the function above to remove the sharpening and return it to it's original state. However, it will not be possible to do this if the sharpening uses USM: there will always be artifacts of the original sharpening remaining.

nospam
still missing the point, which you almost had.

Sandman
Just the plain facts.

Eric Stevens
I'm afraid they are not as plain or as straightforward as you would like to have them.

nospam
they're very plain and straightforward.

here it is again: everything in lightroom is reversible.

simple.