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Author Topic: Darkening, brightening and information loss  (Read 9008 times)
Eric Myrvaagnes
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« Reply #40 on: July 16, 2011, 06:28:55 PM »
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But there's no (good) reason to assume that any slider is the inverse of any other slider in LR. The only version of the OP's questionthat makes sense is if you end up with EACH slider in the SAME position at the end, but do the operations in a different order (NOT on different sliders). As numerous posters have mentioned, LR does its processing based only on the position of the sliders at rendering time and not on the order in which they were manipulated in getting to that final position. And the user has no control over the order in which LR does the processing steps.
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-Eric Myrvaagnes

http://myrvaagnes.com  Visit my website. New images each season.
Richowens
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« Reply #41 on: July 16, 2011, 07:00:45 PM »
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Hans,

  Perhaps I did not make myself clear. On picture 1 he slid the slider for exposure to 4.34, recovery he slid to 2.76, in that order.
 On picture 2 he slid the recovery slider to 2.76, exposure he slid to 4.34, in that order.

  Both pictures will be the same no matter what the order. He did not put both exposure and recovery to say 3.39 on picture 1, then set both exposure and recovery to say 2.54 on picture 2. If he did that of course they will look different.

Rich
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Schewe
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« Reply #42 on: July 16, 2011, 08:00:38 PM »
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Yeah, ya know, let's be crystal clear on this...the order of the settings adjustment makes zero difference to the order that ACR/LR will end up doing the processing. They are two completely different animals.

The parametric nature of the settings means you can keep going back and changing the settings applied to the raw file (not yet processed) and keep changing them forever and have zero impact on the raw file itself–only the settings stored.

Once you process the rendered file, it doesn't matter how many times your changed the settings and in what order, the actual order of the processing pipeline is dictated by the ACR/LR engineering team. The pipeline will always process the image in it's own internal optimal order which is fixed and unchanged by the user...
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kenlip
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« Reply #43 on: July 16, 2011, 10:09:11 PM »
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I didn't mention order...
As said above fill light is not the inverse of exposure and the also btw. have different metrics, so an equal amount does not make sense. Exposure sets the white point, fill light lifts the shadows and does not move the white point.

But I did mention order.  

Please read my posting again, with specific attention on lines 4 and 5.

That was the whole point of the exercise.  

The OP was suggesting that, if LR used integer maths or even floating point to just one or two decimal points, then as one wanged sliders back and forth the rounding errors would induce artifacts.  Order of using the sliders might make a difference if LR wasn't using floating point maths for its algorithms and if it doesn't have other algorithms built in to optimise the image irrespective of the order in which the sliders are used.

Most of us are in agreement that LR uses floating point and has algorithms to make the sequence of using the sliders irrelevant.  


Ken

Ken

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Schewe
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« Reply #44 on: July 16, 2011, 10:31:35 PM »
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Order of using the sliders might make a difference if LR wasn't using floating point maths for its algorithms and if it doesn't have other algorithms built in to optimise the image irrespective of the order in which the sliders are used.

And this is where I say, forget about it...regardless of HOW ACR/LR is doing what it's doing, the order that the user makes adjustment is irrelevant and will have ZERO impact on the results. Ya got that yet? Do what you want to do with the adjustments and ACR/LR will do what it wants to do with the adjustments and in the order ACR/LR decides is the optimal order. Really, we need to move on from this...
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Richowens
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« Reply #45 on: July 16, 2011, 11:45:45 PM »
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You know..........sometimes t's better to marvel at the magic show than to try to figure out how the magician does it.
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Alan Goldhammer
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« Reply #46 on: July 17, 2011, 08:05:22 AM »
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And this is where I say, forget about it...regardless of HOW ACR/LR is doing what it's doing, the order that the user makes adjustment is irrelevant and will have ZERO impact on the results. Ya got that yet? Do what you want to do with the adjustments and ACR/LR will do what it wants to do with the adjustments and in the order ACR/LR decides is the optimal order. Really, we need to move on from this...
From a visual point of view this is probably true but from a computational point of view it may not be IF AND ONLY IF LR does its calculations in a different order depending on how the user has made the changes.  I suspect that this will not happen since LR probably only recognizes the final changes to the sliders and will optimize the order (otherwise the code starts to become really complicated).  The only ones who can answer this for sure are the Adobe LR engineers and they probably have much better things to do with their time.
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Schewe
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« Reply #47 on: July 17, 2011, 10:28:13 AM »
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From a visual point of view this is probably true but from a computational point of view it may not be IF AND ONLY IF LR does its calculations in a different order depending on how the user has made the changes.

Again...the order that the user does something has ZERO (you understand the word zero) impact on the order that ACR/LR does it's thing.

I'm not sure why it's so hard to understand that the ACR/LR pipeline is pre-determined by the engineers to always do things in the order that will be optimal for processing, not the order that the user may have adjusted things. Also understand that the order of the pipeline is really, really complicated using a series of pretty impressive algorithms to deal with tone and color as well as sharpening and noise reduction and through in local adjustments and even lens corrections. Really, you don't want to know how to make the sausage...just eat it.
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Alan Goldhammer
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« Reply #48 on: July 17, 2011, 10:56:54 AM »
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Again...the order that the user does something has ZERO (you understand the word zero) impact on the order that ACR/LR does it's thing.

I'm not sure why it's so hard to understand that the ACR/LR pipeline is pre-determined by the engineers to always do things in the order that will be optimal for processing, not the order that the user may have adjusted things. Also understand that the order of the pipeline is really, really complicated using a series of pretty impressive algorithms to deal with tone and color as well as sharpening and noise reduction and through in local adjustments and even lens corrections. Really, you don't want to know how to make the sausage...just eat it.
Jeff, you are not reading my statement correctly (and I am in your camp on this).  The only people who really can answer the question definitively are the software engineers who built the program.  I've done enough programming in my lifetime to realize that the order one does certain calculations with algorithms can lead to disparities in data.  Usually these disparities are meaningless since they are down to many zeros to the right of the decimal point but they are there none-the-less (and even if they were present in LR as the result of calculations they would be meaningless).  I agree that Adobe has designed an optimal product that will give excellent results and that there is NO IMPACT on the rendered image when it comes to printing.  On this we are in violent agreement.
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Hans Kruse
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« Reply #49 on: July 17, 2011, 11:18:57 AM »
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Hans,

  Perhaps I did not make myself clear. On picture 1 he slid the slider for exposure to 4.34, recovery he slid to 2.76, in that order.
 On picture 2 he slid the recovery slider to 2.76, exposure he slid to 4.34, in that order.

  Both pictures will be the same no matter what the order. He did not put both exposure and recovery to say 3.39 on picture 1, then set both exposure and recovery to say 2.54 on picture 2. If he did that of course they will look different.

Rich

You are right, I somehow misread the post I responded to with the examples. I guess I thought we had left the discussion about the order at that point Wink
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Schewe
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« Reply #50 on: July 18, 2011, 03:59:05 AM »
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I've done enough programming in my lifetime to realize that the order one does certain calculations with algorithms can lead to disparities in data.

Uh huh...and if the order that the user might make an adjustments had ANY impact on the processing order, that would be interesting and useful.

Alas, that is not the case...regardless of what the user may do, the guys from Adobe have already chosen the optimal processing pipeline for ACR/LR. Regardless of what the user may or may not do, the actual order that ACR/LR has already been determined and fixed by the engineers...

While it's possible for a user to incorrectly adjust the settings for a given image, nothing the user might do will alter the order in which ACR/LR processes the image. Sure, users can screw up an image by selecting inappropriate settings but the order that the user may make the adjustments is simply not a factor.

OK? Can we move on? I really doesn't matter HOW the engineers do it (really, it doesn't) what matters is how you use the settings...

Are we done yet?
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Alan Goldhammer
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« Reply #51 on: July 18, 2011, 06:08:57 AM »
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Are we done yet?
I'm done! Wink
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