Google| Subject | Re: Lenses and sharpening |
| From | Eric Stevens |
| Date | 2014-09-20 04:01 (2014-09-20 14:01) |
| Message-ID | <v4kp1alrgpj4ik0omiu76lccp5gen0q69c@4ax.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Sandman |
| Followups | nospam (5m) > Eric Stevens Sandman (9h & 18m) > Eric Stevens |
On 19 Sep 2014 06:50:24 GMT, Sandman <mr@sandman.net>wrote:
SandmanNo, quite correct. See, for example: http://tinyurl.com/mbrhs3e
In article <qogm1a5hikba6q578as28s1el6u3l7v9se@4ax.com>, Eric Stevens wrote:SandmanEric StevensSandmanWell, we all know that YOU rarely have the first clue about what you're talking about, so I have no problem understanding why you're here supporting ignorant Floyd.Eric Stevens
Floyd's usage is strictly in accordance with http://en.wikipedia.org/wiki/Reversible_process_%28thermodynamics%29
Great input, if the topic had been about thermodynamics.
The article is about thermodynamics. The concepts and the mathematics and the concept of entropy apply to a number of topics including information processing which, in turn, includes image processing.
Incorrect.
I've just explained that in another article.SandmanEric StevensSandman
as it applies information theory. If you think there is no room for reversible processes in information theory see http://tinyurl.com/otp5pug
Why can't you read?1. Floyd thinks that HPS + JPG compression can be reversed. It can not.Eric Stevens
He never claimed that the JPG can be reversed.
Yes, he did. His example included JPG compression and the recieving end being able to reverse a process that took place before the JPG compression.
Yes, it should be that the original sharpening can be recovered.Eric StevensSandman
As I have already written, he said that the original image can be recovered after sharpening by HPS even after the image has been saved as a JPG.
Which is incorrect.
I *know* how he used the term and I have already explained in detail. A non-destructive work flow is not a fully reversible process.Sandman2. Floyd thinks that a non-destructive workflow is not a reversible process, it is.Eric Stevens
It's not a reversible process in the way that he used the term.
I don't care how you think he "used" the term. A non-destructive workflow is a reversible process in every sense of the term.
Say I have a bomb, and cause it to explode. If I then with superhuman speed capture all the escaping gases and stuff them back into the ruptured casing, and then slam the casing shut, I might be said to have fully reversed the process. (In fact, that would not be correct in thermodynamic terms).
Say I have another bomb and after I have exploded the first bomb I put the second bomb in it's place. It might now look as if the first bomb had never explodedbut I have not reversed the changes to the first bomb: I have merely substituted for it.
Then you should have found the part I just quoted.Eric StevensSandman
You previously quoted from a dictionary. Here is what the New Shorter Oxford English Dictionary says of this particular usage of 'reversible':
My quote was *from* Oxford.
You will see why this does not apply to the LR situation when you consider my example of the bombs.Eric StevensSandman
"2 Physics. Of a change or process: that is capable of complete and detailed reversal; spec designating or undergoing an ideal change in which a system is thermodynamic equilibrium at all times."
Funny how you had to ignore the part of the Oxford dictionary that wasn't about physics - which has nothing to do with image processing - and was specifically about "of the effects of a process or condition" which is exactly what we're talking about:
(of the effects of a process or condition) capable of being reversed so that the previous state or situation is restored
Don't quote dictionaries if you don't know which part of them to quote.But I do know which part to quote. I quoted the bit that I did to show Floyd was correct in his usage. That doesn't mean that it is the only possible meaning for the term reversible but, in this case, the use of the other meanings is incorrect.
Why not quote the part about chemistry while you're at it, Eric?It uses external storage for the edit data. Lightroom uses the database but it can also use the sidecar files. Where you store the edit data is irrelevant. The argument is equally valid if the edit data is stored inside the image file as does NX-2. It's the fact that the original is not touched and the editing can be constructed from the list of edits which matters.
Chemistry (of a colloid) capable of being changed from a gel into a sol by a reversal of the treatment that turns the sol into a gel.
Obviously Floyd doesn't know what a reversible process is, since he can't change the image from a gel to a sol. Right?Eric StevensSandman
As nospam has so often told us, Lightroom (and other software using side car files)
Lightroom. Does. Not. Use. Sidecar. Files.
True, but it is neither of these which is exported.Eric StevensSandman
do not actually change the file being edited until it is in the process of being exported.
Incorrect. The file is *never* changed. Lightroom has a preview file that is constantly being updated to reflect the adjustment changes you make. This is a JPG file that resides on your hard drive at all times. For every single adjustment you make in Lightroom, it creates a current-state preview file on disk. The original file is never touched.
How can it be identical, how can it contain the same amount of image information if it is a much smaller file. I've already commented mine are generally between 50% and 20% of the size of the original?Eric StevensSandman
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.
Incorrect, what you see on the screen is exactly what the exported file - if you even export it - will look like. It's not simplified, and it's not a representation of something else.
Thhe fact that you can't reverse them in the image file is what this argument is all about. Doing them over again but differently is not reversing them.Eric StevensSandman
Once you export the file - that's it. You cannot reverse the changes.
Incorrect. All changes are still non-destructive in your workflow and you can reverse 100% of them at all times. Just because you can't reverse them *in the exported file* doesn't mean they're not reversible. This is what you need to learn.
Doing them over again but differently is not reversing them.Eric StevensSandman
All you can do is edit the original all over again but this time slightly differently.
I.e. it is 100% reversible.
It's only executed on the preview file.Eric StevensSandman
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.
It is executed when it is made. Nothing is excuted only when the file is exported. You don't know how this works.
Not necessarily in the sense that Floyd and I use the term.Eric StevensSandman
I do not know the type of sharpening used by Lightroom or whether or not it is truly reversible.
It is 100% truly reversible.
You should ponder on those words. --SandmanJust the plain facts.Eric Stevens
I'm afraid they are not as plain or as straightforward as you would like to have them.
Yes they are, you just don't understand them. Nothing to be ashamed of, there are lots of things you don't understand.
Regards,
Eric Stevens
2014-09-13-
