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Author Topic: smart curve  (Read 7629 times)
stamper
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« on: January 22, 2009, 05:54:09 AM »
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I don't have any affiliation with this program.    Therefore it isn't a "plug". I downloaded it and gave it a try. The curves can used in LAB mode and the results appear to be identical to using curves in LAB mode. My question is how can this be so when the filter doesn't change from RGB to LAB mode?
« Last Edit: January 22, 2009, 05:54:50 AM by stamper » Logged

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« Reply #1 on: January 22, 2009, 09:45:56 AM »
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Quote from: stamper

This us useful why? I can apply a curve and apply a luminosity blend mode IF there's some issue with tone/color alteration at the same time (which was designed to work that way for a specific reason).
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« Reply #2 on: January 22, 2009, 03:49:55 PM »
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coincidentally this same issue just came up at another forum. I have not explored this myself but those interested might take a look-
http://www.alternativephotoshop.com/phpBB3...p?f=14&t=12

Tyler
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digitaldog
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« Reply #3 on: January 22, 2009, 03:54:50 PM »
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Right, the Adobe engineers have it all wrong (since 1990). Millions of images are incorrectly processed.

And then there's this:

http://www.luminous-landscape.com/essays/Curves.shtml

And this:

http://www.luminous-landscape.com/pdf/Curves2.pdf
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Andrew Rodney
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stamper
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« Reply #4 on: January 23, 2009, 02:40:07 AM »
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Quote from: digitaldog
This us useful why? I can apply a curve and apply a luminosity blend mode IF there's some issue with tone/color alteration at the same time (which was designed to work that way for a specific reason).

I wasn't inferring that is was useful. I was curious as to how the filter could make changes to the a and b channels without changing colour modes? You yourself have said in the past that there are problems changing back and forth. I was hoping you would answer the post because you are knowledgeable about these things. I just wondered how it was possible?
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sniper
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« Reply #5 on: January 23, 2009, 05:16:35 AM »
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Quote from: digitaldog
Right, the Adobe engineers have it all wrong (since 1990). Millions of images are incorrectly processed.

And then there's this:

http://www.luminous-landscape.com/essays/Curves.shtml

And this:

http://www.luminous-landscape.com/pdf/Curves2.pdf

I hate to be the one to say it but just because Adobe say it's right doesn't make it so, they may well be right in this case, but we shouldn't automaticly rule out any other possibilites.

A good few years ago a well known airline worked out the correction factor for the effect of rain on it's aircraft windows, it published it's findings and they were accepted pretty much world wide by other airlines, added to the flight manuals of thousands of planes.  About 10 years later an engineer for another airline worked out in his lunch break with a pocket calculator that it was wrong (lots wrong in fact) the first company checked it original figures and guess what they found...  a mistake.
For 10 years millions of people had been flying in planes using the wrong calculations, simply because it was assumed the first company was right.    Wayne
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digitaldog
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« Reply #6 on: January 23, 2009, 08:30:11 AM »
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Quote from: stamper
I wasn't inferring that is was useful. I was curious as to how the filter could make changes to the a and b channels without changing colour modes? You yourself have said in the past that there are problems changing back and forth. I was hoping you would answer the post because you are knowledgeable about these things. I just wondered how it was possible?

How they do it? Have no idea. Maybe they use some RGB to Lab lookup table, maybe they have some algorithm similar to what Adobe has been doing for years with blend modes. Its pretty much a solution in search of a problem.
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Andrew Rodney
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« Reply #7 on: January 23, 2009, 08:35:01 AM »
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Quote from: sniper
I hate to be the one to say it but just because Adobe say it's right doesn't make it so, they may well be right in this case, but we shouldn't automaticly rule out any other possibilites.

Actually the millions of customers and probably billions of images run through Photoshop in the past 19 years suggests its right, or at least its not obviously wrong! Thomas Knoll is quoted in Mark's piece about WHY Adobe did what they did but the fact remains, they have a back door to producing a result whereby the saturation increase which most users find desirable can be handled. Again, this is all about a niche group of people looking for a solution where a problem doesn't really exist, at least for the huge majority of Photoshop users.

Got nothing to do with calculators, it has to do with the results in editing an image and then outputting it. We've got a very long and successful history of image editing that more than suggests Thomas was correct (again).

This debate is even less useful than "Mac vs. PC" or "Nikon vs Canon", "Film vs. Digital" or Atlantic ocean versus Pacific ocean.
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Andrew Rodney
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« Reply #8 on: January 23, 2009, 09:32:43 AM »
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So because millions of people use Adobes product without knowing it may not be the best way of doing something makes Adobe right?  No that just means they don't realise there are other possibly better ways.
A closed mind is a terrible thing, just because Thomas Knoll says something we must all slavishly believe it?  
Wayne
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digitaldog
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« Reply #9 on: January 23, 2009, 09:39:00 AM »
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Quote from: sniper
So because millions of people use Adobes product without knowing it may not be the best way of doing something makes Adobe right?  No that just means they don't realise there are other possibly better ways.
A closed mind is a terrible thing, just because Thomas Knoll says something we must all slavishly believe it?  
Wayne


OK, the millions of images, viewed, processed and printed are wrong.

The proof is in the proof. With nearly 20 years of use and millions of users, Adobe has no evidence, at least in terms of this so called issue with curves, that this isn't a problem?

Now what evidence do you have otherwise?

My mind isn't closed, I actually did something you should, I tried both processes and surprise, 99 times out of 100, what Thomas said is true. And for that one time? Well he provided us a blend mode to handle that.

If there's a better way, prove it.
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Andrew Rodney
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« Reply #10 on: January 23, 2009, 11:32:49 AM »
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Quote from: digitaldog
OK, the millions of images, viewed, processed and printed are wrong.

The proof is in the proof. With nearly 20 years of use and millions of users, Adobe has no evidence, at least in terms of this so called issue with curves, that this isn't a problem?

Now what evidence do you have otherwise?

My mind isn't closed, I actually did something you should, I tried both processes and surprise, 99 times out of 100, what Thomas said is true. And for that one time? Well he provided us a blend mode to handle that.

If there's a better way, prove it.

I didn't say there was a better way, I said there might be a better way.  And I certainly don't have to prove it to you or anybody else.  What I did say was that Adobes may not be the best way just because it's Adobes way!
You "proof" consists of millions of images being processed,  so what? millions of people drink cheap crap coffee everyday, that doesn't make it the best coffee in the world, just the most convenient.
In essence I'm saying don't believe it just because Adobe say so, do what you did and find out for yourself.  If Adobe said up was down would you believe that? some here would.  Wayne
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digitaldog
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« Reply #11 on: January 23, 2009, 12:31:58 PM »
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Quote from: sniper
I didn't say there was a better way, I said there might be a better way.

And there might be technology that will make pigs file and allow humans to transport themselves to the USS Enterprise.

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And I certainly don't have to prove it to you or anybody else.

No, you don't. That makes it especially easy to dismiss your remakes. Basic scientific methodically states* that its not up to me to prove a hypothesis or theory, its up to me (or others) to disprove it!  Considering the number of users of this product, where's the smoking gun that the current implementation is anything but adequate if not better? Where's the scientific methodically? Dan M. suggested that the curves in Photoshop are broken, Mark's article used the scientific method to dismiss his claims, Dan never responded to Mark's points even though he was asked to. While some could say Mark's piece isn't the end all summery that puts this scientific debate to rest, he at least conducted himself in a scientific manner with his essays and as far as I know, they have not been disproved let alone argued. As such, I'm far more willing to believe what I see, have tested and what I've read about just as I'm far more inclined to believe in the theory of evolution then those who say the world was created 6 thousand years ago.

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You "proof" consists of millions of images being processed,  so what? millions of people drink cheap crap coffee everyday, that doesn't make it the best coffee in the world, just the most convenient.
In essence I'm saying don't believe it just because Adobe say so, do what you did and find out for yourself.  If Adobe said up was down would you believe that? some here would.  Wayne

IOW, you're just a skeptic.

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*The scientific method requires a hypothesis to be eliminated if experiments repeatedly contradict predictions. No matter how great a hypothesis sounds, it is only as good as it's ability to consistently predict experimental results. It should also be noted that a theory or hypothesis is not meaningful if it is not quantitative and testable. If a theory does not allow for predictions and experimental research to confirm these predictions, than it is not a scientific theory.

The hypothesis is, Photoshop curves are or are not ideally designed based on a change in saturation with the tonal adjustment. Repeated usage of the curves by millions of users on perhaps billions of images have or have not provided the desired effect by the end user? End users are or are not producing the desired edit using the curves as designed? End users do or do not have the ability to alter this behavior for times in which they do want to lock the appearance of saturation when using curves?
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Andrew Rodney
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« Reply #12 on: February 14, 2009, 04:43:49 AM »
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Quote from: digitaldog
Right, the Adobe engineers have it all wrong (since 1990). Millions of images are incorrectly processed.

And then there's this:

http://www.luminous-landscape.com/essays/Curves.shtml

And this:

http://www.luminous-landscape.com/pdf/Curves2.pdf

What so if someone bakes their thoughts into a PDF it suddenly becomes tantamount to the truth. The hue and saturation shifts in a normal curves implementation are caused by fundermental characteristics of tristimulus RBG colourspaces and the way that luminosity is defined within Photoshop.
It is not as Thomas Knoll says a 'saturation boost' that replicates the tonal response of colour film. To educate yourself about the why these shifts occur in both normal curves and those blended on luminosity I suggest you read the manuals at http://freegamma.com/package.shtml and to get the full story read Les Walkling's dissertation entitled 'New techniques in the production of colour images in the field of fine art photography' which probably can be most easily obtained by contacting the author directly at      

All the best
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Tim Lookingbill
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« Reply #13 on: February 14, 2009, 05:35:44 AM »
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Viewing saturation levels on a bright display looks a lot different viewing on a print.

This is what all of this is about.

Coming from a commercial art and fine art painting background working with expensive dyes, Windsor Newton watercolors and acrylics, I can even see why Thomas Knoll went this route because in my work it IS very desirable to maintain contrast induced saturation especially into the shadows due to the reflectance characteristics when ink hits paper.

Applying contrast using a luminosity curve injects black ink or desaturates color which translates into dull looking prints.


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digitaldog
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« Reply #14 on: February 15, 2009, 03:04:52 PM »
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Quote from: TylerB
coincidentally this same issue just came up at another forum. I have not explored this myself but those interested might take a look-
http://www.alternativephotoshop.com/phpBB3...p?f=14&t=12

Tyler

Actually, a clever fellow by the name of Marco Ugolini figured out how to do this within Photoshop without the need of any other exotic products, give it a try:

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1) Open an RGB file, ANY RGB file.

2) Create a new pixel layer, and fill it with either pure White, pure Black, or 50% Gray.

3) Change this new layer's blend mode to "Color"

What you are seeing here now is Lobster's fabled RGB luminosity mask! Ya know, the one that doesn't change the underlying pixels when set in Luminosity blend mode.

5) So, now select the whole canvas, and execute Edit > Copy Merged.

6) With the Luminosity mask in your Clipboard, toss the Color blend mode pixel layer.

7) Paste the Luminosity mask above the RGB image; set it in Luminosity blend mode, like so:


Done! You can clip a Curves or Levels or Channel Mixer or Exposure or Brightness and Contrast or Photo Filter adjustment layer to the Luminosity mask to make changes to the underlying image without changing hue. Once clipped to the Luminosity mask, the adjustment layer can remain in Normal mode.

By the way, from a limited amount of testing I've done, I don't see any "wow!" differences between using, say, the same exact Curve adjustment layer clipped to a Luminosity mask or by itself in Luminosity mode. The differences are NEGLIGIBLE! No, actually let me say that the Curves layer by itself, in Luminosity mode, appears to me like it's doing a BETTER job of preserving the finer detail in the image!
« Last Edit: February 15, 2009, 03:05:46 PM by digitaldog » Logged

Andrew Rodney
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BernardLanguillier
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« Reply #15 on: February 16, 2009, 02:35:59 AM »
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Quote from: digitaldog
No, you don't. That makes it especially easy to dismiss your remakes. Basic scientific methodically states* that its not up to me to prove a hypothesis or theory, its up to me (or others) to disprove it!

That makes me think I should start re-reading 'Zen or the art of motorcycle maintenance'.

Cheers,
Bernard

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A few images online here!
Chris_T
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« Reply #16 on: February 16, 2009, 08:20:21 AM »
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Quote from: sniper
So because millions of people use Adobes product without knowing it may not be the best way of doing something makes Adobe right?  No that just means they don't realise there are other possibly better ways.
A closed mind is a terrible thing, just because Thomas Knoll says something we must all slavishly believe it?  
Wayne

Well said.

The same can be said about M$FT's products. By monopolyzing the market, they can sell what they want and charge what they want. Most users are left with few alternatives. Those with vested interest are wise not to step on the gorillas.

Monopoly without competitions stifles creativity.
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Schewe
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« Reply #17 on: February 16, 2009, 12:00:28 PM »
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Quote from: sniper
A closed mind is a terrible thing, just because Thomas Knoll says something we must all slavishly believe it?

You need to separate what Thomas says from what "Adobe says"...Thomas is an individual person...Adobe is a corporate identity. It's been my experience over the last 10 years (the length of time I've worked with Thomas Knoll on "things") that if Thomas DOES say something, you would do yourself a favor to believe it because Thomas does not "lie" (he really doesn't have the bandwidth to "make something up) and he honestly and truly does want to do "the right thing". So, his motives, when he says something, are pretty easy to know. And when he says something about digital imaging/raw processing, you really have to consider him the leading authority in the field. So, to ignore what Thomas says is pretty stupid.

It actually sounds like it's YOUR mind that is closed...
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Peter_DL
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« Reply #18 on: February 17, 2009, 04:59:06 PM »
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Quote from: tlooknbill
... I can even see why Thomas Knoll went this route because in my work it IS very desirable to maintain contrast induced saturation especially into the shadows due to the reflectance characteristics when ink hits paper.

Applying contrast using a luminosity curve injects black ink or desaturates color which translates into dull looking prints.
So what exactly did Thomas Knoll say and in which context. Here’s an original comment by him (dated Oct. 11, 2005, Adobe Camera Raw Forum, Topic: Color reproduction in digital photography):

"While developing Camera Raw, I experimented with a pure luminance curve (as Simon suggests). However, based on my testing results, I rejected this algoirthm since it produced results that were most often visually worse looking that the tone curve algorithm actually used by Camera Raw (which is a special hue-preserving curve, NOT three indepent curves as Simon incorrectly assumed). The saturation effects that Simon considers a defect is actually something that most users actually want."

In my opinion it was based on a misunderstanding. Simon was not suggesting a "luminance curve" like with Luminosity blend mode in Photoshop. More (smart) curves.

Peter

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digitaldog
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« Reply #19 on: February 17, 2009, 05:05:57 PM »
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Quote from: DPL
In my opinion it was based on a misunderstanding. Simon was not suggesting a "luminance curve" like with Luminosity blend mode in Photoshop.

Simon may not have but a so called imaging expert in love with polishing truds in LAB has repeatedly said that the so called "Master RGB curves" are bad, wrong and don't belong in a professional package. I'm paraphrasing but have the exact quotes. This lead to the published articles on this site by Mark, referenced above.
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Andrew Rodney
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