Eric Stevens
On Thu, 18 Sep 2014 07:52:56 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-18 09:03:35 +0000, Eric Stevens <eric.stevens@sum.co.nz>said:

Eric Stevens
On Wed, 17 Sep 2014 21:32:17 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-18 04:17:59 +0000, floyd@apaflo.com (Floyd L. Davidson) said:

Floyd L. Davidson
Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-18 01:00:46 +0000, Eric Stevens <eric.stevens@sum.co.nz>said:

Eric Stevens
On Wed, 17 Sep 2014 06:05:14 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-17 09:22:00 +0000, Eric Stevens <eric.stevens@sum.co.nz>said:

Eric Stevens
On Tue, 16 Sep 2014 22:27:43 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-17 04:08:19 +0000, Eric Stevens <eric.stevens@sum.co.nz>said:

Eric Stevens
On Tue, 16 Sep 2014 07:53:15 -0700, Savageduck <savageduck1@{REMOVESPAM}me.com>wrote:

Savageduck
On 2014-09-16 10:36:29 +0000, floyd@apaflo.com (Floyd L. Davidson) said:

Eric Stevens
--- snip ---

Savageduck
The reverse process performed on a lossy, compressed JPEG is not going to reverse the HPF to return to the original state. That was lost once the save was executed.

Eric Stevens
That's why I never included a conversion to JPG in my example of a reversible process.

Savageduck
Â...but that genius Floyd did.

Eric Stevens
--- snip ---

No one who understood what we were trying to talk about would claim that a JPG conversion is a reversible process.

Savageduck
Â...but that genius Floyd did.

Eric Stevens
I've had a look and I cant see where. Could you refer me to the message?

Savageduck
With pleasure.

That wasnâEUR(Tm)t too tough to find: Posted: Mon, 15 Sep 2014 13:44:18 -0500 Message ID: <8738bs2076.fld@barrow.com>

Wherein Floyd stated the following:

âEURoeA non-destructive workflow means you can *undo* and then *redo*.

That is not a reversible function.

For example, you can add sharpening with a high pass sharpen tool to an image, save it as a JPEG, send it to someone else, and they can use a blur tool to reverse the sharpen.

If the sharpening is done with UnsharpMask that cannot be done. USM is not reversible.âEUR?

Note, the words, âEURoesave it as a JPEG,âEUR?.

As I said, that genius Floyd did.

Floyd L. Davidson
So we now we know you can't read.

What I said was that *high pass sharpen is reversible*. It is, even if a few people are unable to either understand or accept that it is.

Savageduck
From a lossy, compressed JPEG? You did say ?save it as a JPEG? didn?t you? Have you also developed the mathematics to reverse the compression and loss in that High-Pass sharpened file, so that you can return it to its original state?

HPS might well be reversible, but returning the file to its truly original state after being saved as a JPEG is improbable.

Eric Stevens
It's not the file that is being returned to the original state: it's the sharpening.

Savageduck
Holy spluttering wake up call!! Eric, just take a look at what you have written and tell me you arenÂ’t grasping at straws?

Eric Stevens
I'm talking about the very subject that was being discussed at the start of this now entirely wrecked thread.

Savageduck
However, I have the tools to do that, with HSP, and even USM regardless of how much you stamp your feet and say I can?t.

Eric Stevens
But you are not reversing it: you are reverting and replacing it. Not the same thing.

Savageduck
Actually, I am not replacing anything, and in an odd way I am not “reversing” the effect of any of those sharpening methods. I am readjusting the parameters, and in making that readjustment I can end up in any state, including the original so I can produce another version. In fact I am not even going to go through the pointless esoteric exercise of working on that saved JPEG, it will remain as a snapshot of the state of the working image file when it was saved.

Eric Stevens
If you are still talking about Lightroom, the edited image is only created when it is exported.

You can adjust what you like before that but all you are changing is a simplified simulacrum of what the final image will be. When you export it, whatever you get is fixed. You can of course treat it as a new image and re-edit it, but that comes back to Floyd's original point: if in the first edit you sharpened the image with USM you will not be able to restore the exact sharpness of the original by editing the exported image. USM is not fully reversible.

Savageduck
I can use the layer mask which is part of the *Smart Filter* and selectively remove or reduce the filterÂ’s effect as I please. You still have something to learn regarding just how you deal with *Smart Objects* & *Smart Filters* in Photoshop. All I have to do is double click on the *Smart Filter* layer and the filter dialog will reopen and I can re adjust away, and if I donÂ’t want that particular sharpening and want to return to an original state without the issues presented by a lossy, compressed JPEG, I can do one of three things; return parameters to their original, pre-effect state, turn off the visibility of the adjustment layer (you can do that you know), or just delete the layer.

Eric Stevens
This type of legerdemain is not what is meant by fully reversible in the context that Floyd was using it.

Savageduck
Whatever I do, I have reversed what was presented, reverting to the original uncompressed state, without any compression artifact issues. As I have said before, that JPEG was nothing but aversion, or a snapshot of the current state of the working image file. I can go on to have many versions all of the same quality, none showing generational degradation.

Unlike Floyd, you actually have the opportunity to see for yourself that what I am saying is true, Just open PS and experiment. Learn something about the capability of the software you have installed and are allegedly using.

Eric Stevens
I know what you are saying and I understand what you are saying, but you are missing the point.

I suggest that you actually start thinking about what is happening when you do these things in the context of what Floyd originally said.