Lenses and sharpening

On 2014-09-17 07:25:45 +0000, (Floyd L. Davidson) said:

Savageduck wrote:
On 2014-09-17 04:23:29 +0000, Eric Stevens said:
What then is a reversible process?

We are descending into silliness here. A reversible
process is one where any changes made in the execution
of that process can be reversed to revert to the
original state

You have long since ceased anything not silly. But
using your own definitions of very technical terms just
leads to farther down the same path. Your definition is
trivial, and not valid in a technical discussion.

Reversiblility is not equivalent to revertability.

And undo function (linear or not) reverts. That is it
goes back to a previous state.

A "reversible function" incrementally moves forward,
or backward, in granular steps that are necessarily
small compared to the potential range.

An excellent definition for the difference between a
reversible function and a non-reversible function is
that in an isolated system entropy change will be
greater than 0 with a non-reversible process, and will
be 0 with a reversible process.

That means there is one original state, and one current
state that derives from a specific process that cannot
produce any other state; and if 1) the process is
reversible there is only one possible state if the
process moves backwards, while 2) there are multiple
different possible states if an irrevsible process moves
backwards.

https://dl.dropboxusercontent.com/u/1295663/Photo%20Jan%2005%2C%2012%2038%2052.jpg

--


Regards,

Savageduck

Savageduck wrote:
https://dl.dropboxusercontent.com/u/...%2038%2052.jpg

I'm sure you do, probably far more often that a mere 20
times a day, considering how often you respond with
shallow comments on topics that you can't understand.
Why not just read and try to learn?

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)

Savageduck wrote:
Alfred's query regarding USM. We ended up discussing HPS & USM and the
qualities of both. I know what Floyd was talking about.
Then why are you rabitting on about non-destructive
work flows?

Because there is more to this thread, and NG than the
arcane pontificating of Floyd D, and more over he, or
anybody else here doesnâEUR(Tm)t control the flow and drift
of any thread.

There is much more to post processing than FloydâEUR(Tm)s way
of doing things. Even though he denies the reality of
the tools available to the Photoshop user.

You and nospam continue to try shifting everything to
the one thing you claim to know, which is how to read an
Abobe user manual.

Nobody has denied that Photoshop users can do this or
that. The problem is that Photoshop's capabilities, or
lack thereof, are not the topic in this thread no matter
how limited your personal horizons are.

The topic was sharpening, and the differences in ways to
do that. Abobe's programs are not even close to the
only way to sharpen. In fact *most* users that actually
get into the more sophisticated aspects of sharpening
cease using anything that Abobe provides for that
purpose, and shift to better tools.

Generic atributes of sharpen tools can and should be
discussed absent references to specific implementations.
When specific attributes are discussed it doesn't make a
great deal of sense to look at low end products designed
to appeal to the lowest common denominator, as might
well be discussed in your "Abobe Tools for Dummies"
manual.

--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska)

On Wed, 17 Sep 2014 01:29:00 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

That is a good move on your part. Start sticking with
what Adobe calls it, and in the process use appropriate
terms.

adobe didn't come up with the name. it's what everyone calls it,
because it's non-destructive.

But that doesn't make the processes employed reversible.

who cares.

what matters is the results, not micromanaging every step of the way.

a non-destructive workflow is reversible. period.

So you accept that you are not talking about the same thing that Floyd
was talking about, and that you don't care.
--

Regards,

Eric Stevens

On Tue, 16 Sep 2014 22:27:43 -0700, Savageduck
wrote:

On 2014-09-17 04:08:19 +0000, Eric Stevens said:

On Tue, 16 Sep 2014 07:53:15 -0700, Savageduck
wrote:

On 2014-09-16 10:36:29 +0000, (Floyd L. Davidson) said:

Savageduck wrote:
So? The fact still remains, regardless of personal
opinion about Adobe, Lightroom, & Photoshop, those using
that software have the ability to maintain a fully
non-destructive, and reversible workflow, that includes
reversing the effects of any filter including USM.

It's not a "reversible" workflow. The correct terms
would be either a non-linear undo, or simply that it
can be reverted.

I guess you are in complete denial with regard to the capabilities of
current versions of Lightroom & Photoshop, so it doesn?t really matter
what you want the correct terms would be. I will take ?reversible? out
of my obviously too hyperbolic for you, description of the capabilities
of those Adobe products, and just continue to use the word Adobe uses,
?non-destructive?.

âEUR¦and if you are going to start that reverse
mathematical operation from a compressed, & lossy JPEG,
good luck getting back to where you started.

Your workflow, even if non-destructive, will be totally
unable to deal with reverting any previous editing
with the exception of processes, such as sharpen (not
USM), that are reversible.

It seems that you have never worked with a truly non-destructive
workflow, with Photoshop and Lightroom I have a totally reversible
workflow which can deal with reverting crops, spot removal, content
aware fill, content aware move, any of the various grad filters
available, and filters, including the notorious USM.

The reason that all this argument is underway is that you and nospam
fail to recognise that a "totally reversible work flow" is one thing
but a reversible process is another. What Floyd has been saying is
that sharpening with a high-pass filter is basically the same as
Gaussian blur except that one goes forward and the other goes
backwards. Whatever you do with one can be undone with the other.

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.

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

This is not the same as just cancelling the operation as you do when you
delete it from a sidecar file.

We have an apples & oranges issue here I have been speaking of the two
varieties of non-destructive workflow available to PS and LR users,
they are not the same. What you have said above is sort of correct for
Lightroom, but not for Photoshop where there are no sidecar, or catalog
files. you should learn the difference.

As I have said in some other responses of mine, the JPEG which might be
produced is just a compressed, lossy snapshot of the actual,
non-destructively adjusted, and uncompressed layered PSD, or TIF. It is
best to consider it a version, and there is no point in even trying to
rework it. Call it ?version-1.jpg?. Once you are done with readjusting
the layered PSD/TIF you can produce ?version-2.jpg?, and still have the
ability to return to the working PSD/TIF to produce a ?version-3.jpg?.

The product of a non-destructive workflow is not a JPEG, and there is
little point in doing any reversion work in those JPEGs other than some
polishing tweaks.

Obviously there is nothing I can say or demonstrate to convince you
that I am able to do what I say I can with LR &/or PS. You are stuck in
a World void of Adobe where you spin your knowledge of fundamental
technical minutia into a shield of denial. I will not be, nor do I
strive to be the the technical wizard you obviously are, but this is
one of those times where you have not moved with the times.

As I said when I first came into this thread, I fully expected you to
tell me I was wrong and an ignoramus (which I might well be regarding
some stuff), and you met that expectation, and there isn?t much point
in going any further and we should just agree to disagree, you in your
World, and me in mine.

You could always try to understand what he (and I) are really saying.
It's not what you seem to think it is.

What you claim isn’t actually 100% possible once you are trying to
reverse changes to a JPEG. It might look close, but an exact reversal,
never. However, I can make that exact reversal using the tools I (&
you) have available in Photoshop.

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

Regards,

Eric Stevens

On Tue, 16 Sep 2014 22:13:43 -0700, Savageduck
wrote:

On 2014-09-17 03:48:48 +0000, Eric Stevens said:

On Tue, 16 Sep 2014 09:12:12 +0100, Martin Brown
wrote:

On 16/09/2014 05:37, John McWilliams wrote:
On 9/15/14 PDT, 7:07 PM, Floyd L. Davidson wrote:
Savageduck wrote:

I got what Floyd was talking about when he was talking
of high pass sharpening, and reversing it by applying
the corresponding reverse parameter blur. However, he
also stated above, "UnSharpMask is not reversible". My
point addressed the fact that for some of us, that is
not an entirely valid statement.

IN an environment that supports a saved original copy so that all edits
are non-destructive then that is true.

You can't reverse a process if you have never executed it. If you make
a copy of an image and edit it, you cant reverse the process of
editing by just hauling out your original image. The edited version of
the image remains edited and in most cases there is nothing you can do
to reverse it.

You have Photoshop installed on your computer don't you?
The time has come for you to actually learn how to use it. We will
leave Lightroom for later.

The water is muddied by the several applications which make use of a
sidecar file of some kind to preserve a list of edits which are only
executed when the image file is exported from the editing environment.
Modifying a sidecar file by deleting an editing process from it does
not make that process reversible. It merely makes that process
asthough it never was.

If you make the adjustments in Photoshop with a non-destructive
workflow there is no use of sidecar files or catalog entries as in
Lightroom.

True, but this has nothing to do with whether a process is reversible
or not.

But the mathematics of blurring and of unsharp masking make it
irreversible if you are only given just the processed image.
(and not some hybrid Photoshop workflow encapsulated format)

That is in fact a valid statement. The USM function is
not reversible.

That isn't a opinion, it's a fact.

For one definition of the word!

This seems to have degenerated into a heated and utterly pointless
semantic argument over the meaning of "reversible" that is in conflict
with normal image processing and mathematical parlance.

A mathematical operation is reversible if a strict inverse function
exists that can exactly get you back to where you started.

Any operation can be made non-destructive simply by saving a copy of the
original before applying the irreversible filter but that isn't very
interesting. Some packages do support this sort of safe workflow.
--

Regards,

Eric Stevens
--

Regards,

Eric Stevens

In article , Floyd L. Davidson wrote:

Savageduck:
https://dl.dropboxusercontent.com/u/...%2038%2052.jpg

I'm sure you do, probably far more often that a mere 20 times a day,
considering how often you respond with shallow comments on topics
that you can't understand. Why not just read and try to learn?

Winner in Most Ironic Comment, september 2014.

Congratulations!

--
Sandman[.net]

On Wed, 17 Sep 2014 01:29:01 -0400, nospam
wrote:

In article , Eric Stevens
wrote:


I was saying that I doubt nospam could get his mind around the thought
that "A reversible function and ditto workflow ain't the same thing".
The evidence is that he (and you) can't.

of course i can.

what you and floyd fail to understand is none of that matters to anyone
except you and floyd.

You could have let us alone to get on with it, but no you had continue
at full bore with your missionary work.

users are interested in getting the best results with the least amount
of hassle. they don't want math tutorials or whether a function has an
inverse.

It sounds as though the penny has dropped.

users edit their images with lightroom (or aperture) and can change
anything at any time at any point in the future, *including* altering
unsharp mask. to them, *everything* is reversible. that's the
*reality*.

Which has nothing to with whether or not a process is reversible.

to put it another way, i can change the amount of unsharp mask on an
image i processed a year ago, without having to redo *anything* else i
did. all of the retouching, white balance, etc. remain the same (unless
i choose to adjust those too).

But you can't do that once the image has been exported.
--

Regards,

Eric Stevens

In article , Eric Stevens wrote:

Floyd L. Davidson:
That is a good move on your part. Start sticking with what
Adobe calls it, and in the process use appropriate terms.

nospam:
adobe didn't come up with the name. it's what everyone calls
it, because it's non-destructive.

Eric Stevens:
But that doesn't make the processes employed reversible.

nospam:
who cares.

what matters is the results, not micromanaging every step of the
way.

a non-destructive workflow is reversible. period.

So you accept that you are not talking about the same thing that
Floyd was talking about, and that you don't care.

Floyd has no idea what he's talking about, so as soon as someone knows what
they're talking about, they're by definition not talking about whatever it
is Floyd is babbling about.


--
Sandman[.net]

On Tue, 16 Sep 2014 22:39:44 -0700, Savageduck
wrote:

On 2014-09-17 04:23:29 +0000, Eric Stevens said:

On Tue, 16 Sep 2014 01:34:16 -0700, Savageduck
wrote:

On 2014-09-16 08:05:37 +0000, Eric Stevens said:

On Mon, 15 Sep 2014 22:35:31 -0700, Savageduck
wrote:

On 2014-09-16 02:59:40 +0000, Eric Stevens said:

On Tue, 16 Sep 2014 04:36:08 +0200, android wrote:

In article ,
(Floyd L. Davidson) wrote:

nospam wrote:
In article , Eric Stevens
wrote:

All adjustments made to *Smart Objects*, in Photoshop terms, are
non-destructive.

I fully expect you to tell me I am wrong.

I will tell you that you are discussing a point which is not the point
raised by Floyd. So too is nospam, but that is not surprising.

Floyd was referring to a reversible function: run it forwards and you
get sharpening; run it backwards and you get blur. Or the other way
around if you wish.

there are indeed such functions, but that doesn't matter to users. they
want to edit photos, not learn mathematical theory.

when a user can modify an image and change it later, it's reversible
and that's why it's called a non-destructive workflow.

Squirm all you like, but USM is well known to be a
non-reversible function.

Oki... A reversible function and ditto workflow ain't the same thing. ;-)

I doubt if nospam can get his mind around that thought. :-(

You might have notice that android addressed that comment to Floyd.

So what? I was agreeing with him.

Not quite. You redirected the intended comment to *nospam*, If you
agreed with him your snide response would have poked at Floyd.

I was saying that I doubt nospam could get his mind around the thought
that "A reversible function and ditto workflow ain't the same thing".
The evidence is that he (and you) can't.

A non-destructive workflow makes that irreversible function very
reversible indeed.

You are fudging word meanings. In fact you seem to be demonstrating
that you too don't know the difference between a reversible function
and a reversible work flow.

Not at all. If you reread what I wrote below, you will see that I have
a firm grasp of each of the proposed concepts in this thread.

What then is a reversible process?

We are descending into silliness here. A reversible process is one
where any changes made in the execution of that process can be reversed
to revert to the original state.

A non-destructive work flow does not make a process reversible. All it
does is let you have another go at a process using different settings.


Once that working copy has had USM applied, the layers merged, and
compressed into a JPEG (a destructive action) then Floyd is correct,
the function can no longer be reversed. However, Floyd doesn't see the
concept of the non-destructive workflow because he doesn't, or appears
not to use one. He certainly isn't using what is available to those
running either Lightroom or Photoshop CS6/CC/CC 2014, and ignores that
some here have the ability to take advantage of a non-destructive, or
"reversible" workflow because of the software tools installed on their
computers.


Floyd wasn't even talking about it! He was talking about different
sharpening algorithms.

Floyd specifically addressed high pass sharpening (HPS) in response to
Alfred's query regarding USM. We ended up discussing HPS & USM and the
qualities of both. I know what Floyd was talking about.

Then why are you rabitting on about non-destructive work flows?

Because there is more to this thread, and NG than the arcane
pontificating of Floyd D, and more over he, or anybody else here
doesn’t control the flow and drift of any thread.

Floyd was trying to address the question raised by the OP. The arrival
of nospam and then you on the scene confusing non-destructive editing
with whether a process is reversible or not has brought all sensible
discussion to a halt.

There is much more to post processing than Floyd’s way of doing things.
Even though he denies the reality of the tools available to the
Photoshop user.

I'm afraid it's not a turf war. What Floyd said was perfectly correct
and fundamental. It's quite independent of the editing software.
--

Regards,

Eric Stevens