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Author Topic: How do the basic settings, contrast and the tone curve interact?  (Read 18195 times)

jrp

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Is there a pointer to a good tutorial on how the different tone settings interact?

It is clear how the basic settings work, shifting different parts of the tone curve.  But then we have contrast, which compresses or stretches the tonal range.  And then we have the tonal curve.  The default medium/strong contrast curves drop the shadows.  So there are clearly links between the different sliders.

Now, it may be that there are just different ways of achieving the same transformation of the original tonal curve, but there may be some subtle differences.  Can anyone explain them?
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jrsforums

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #1 on: July 26, 2015, 10:25:33 pm »

Is there a pointer to a good tutorial on how the different tone settings interact?

It is clear how the basic settings work, shifting different parts of the tone curve.  But then we have contrast, which compresses or stretches the tonal range.  And then we have the tonal curve.  The default medium/strong contrast curves drop the shadows.  So there are clearly links between the different sliders.

Now, it may be that there are just different ways of achieving the same transformation of the original tonal curve, but there may be some subtle differences.  Can anyone explain them?

George Jardine does a great job of showing examples of this in his tutorial.

The Image Correction Master Class
http://mulita.com/blog/?page_id=5852
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John

jrp

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #2 on: July 27, 2015, 01:55:11 pm »

Thanks. I like his tutorials, but don't really want / shouldn't need to pay for what I would hope was just factual info. Any alternatives?
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Tim Lookingbill

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #3 on: July 27, 2015, 02:49:02 pm »

Since a Raw capture can contain various levels of dynamic range from scene to scene as well as contain a ton of tone and color data that affect each other with even the slightest adjustment, it's pretty much like asking a sculptor when and why they switch from one tool to the other including the use of their hands to arrive at a finished piece. The sculptor can't reverse engineer what motivated every one of his twiddles and tweaks.

It becomes more of an intuitive process developed through trial and error according to what looks good versus accuracy or realism which is subjective and thus adding another level of complexity in attempting to dissect each editing tools affect on an image. It changes from image to image.

I've never found any use for connecting each tool's affect on individual tonal zones considering some of the sliders compress local contrast and definition in highlights such as in PV2012's Exposure and Highlight sliders. I just try to find a way to brighten the usually dark, dim and flat looking Raw so it retains local and global contrast and definition.

My approach is to first make sure I see every detail in the image from black to brightest white and that sometimes involves sliding Contrast to the far left which sometimes brightens the entire image but in a different way than increasing Exposure especially if the dynamic range is quite large (very high contrast). On narrower DR image it gives an overall chalky look without brightening.

So how is one to pin down what each tool does on every image when there's this many variations on the previewed results?

This tut is probably the best free one you can find online...

https://luminous-landscape.com/tonal-adjustments-in-the-age-of-lightroom-4/
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jrp

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #4 on: July 27, 2015, 04:14:46 pm »

Thanks.  I agree that trial end error can play a large part in processing, which is what I tend to do, but was looking for a more systematic approach.   That's a good tutorial, although it still does not completely nail how or whether the contrast / tone curve features interact.
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jrsforums

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #5 on: July 27, 2015, 05:58:11 pm »

Thanks. I like his tutorials, but don't really want / shouldn't need to pay for what I would hope was just factual info. Any alternatives?

Jardine shows a lot of the subtle differences between the different adjustment....which are difficult to describe in writing, I believe.  I also believe his low price is worth it.

There are big differences, as i remember, between LR 4 and 5/6
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John

Redcrown

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #6 on: July 28, 2015, 05:29:35 pm »

Can't help with a pointer to a single good tutorial, but I've read and participated in several forum discussions on the topic over the years, including some with input from Eric Chan, Adobe's ACR guru.

Eric claims that the ACR adjustments "interact", and should be used, in the way they are layed out in the UI. Top down and left to right. So, Basic adjustments first, Curves second, Detail third, etc. Within Basic, Exposure first, Contrast second, etc. There is one key exception to this, and that is Camera Calibration (profile) which is applied before anything else.

Exposure, Contrast, Whites, and Blacks are all just curves of different shapes (bell, arc, slant, S). Even Clarity is kind of an S-Curve applied with an edge mask. Highlights and Shadows adjustments are very different beasts. They are not curves. They have evolved to use some very complicated and unique logic. Google "Laplacian Filters" for a fun read about that.

Take an Exposure adjustment and a Curve adjustment as an example. Build a positive Exposure adjustment that moves a "highlight" pixel from 210 to 220 (+10 points) when used by itself (no other adjustments). Then build a Curves adjustment that does the same thing when used by itself. Now, when you make both adjustments active at the same time will the sample pixel move 10+10=20 points?

The answer is no. The reason is that whatever adjustment happens second is not starting at the 210 pixel value. It's starting at the 220 pixel value created by the first adjusment. If Eric is correct, the Curves is happening after the Exposure.
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jrsforums

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #7 on: July 29, 2015, 09:20:50 am »

Can't help with a pointer to a single good tutorial, but I've read and participated in several forum discussions on the topic over the years, including some with input from Eric Chan, Adobe's ACR guru.

Eric claims that the ACR adjustments "interact", and should be used, in the way they are layed out in the UI. Top down and left to right. So, Basic adjustments first, Curves second, Detail third, etc. Within Basic, Exposure first, Contrast second, etc. There is one key exception to this, and that is Camera Calibration (profile) which is applied before anything else.

Exposure, Contrast, Whites, and Blacks are all just curves of different shapes (bell, arc, slant, S). Even Clarity is kind of an S-Curve applied with an edge mask. Highlights and Shadows adjustments are very different beasts. They are not curves. They have evolved to use some very complicated and unique logic. Google "Laplacian Filters" for a fun read about that.

Take an Exposure adjustment and a Curve adjustment as an example. Build a positive Exposure adjustment that moves a "highlight" pixel from 210 to 220 (+10 points) when used by itself (no other adjustments). Then build a Curves adjustment that does the same thing when used by itself. Now, when you make both adjustments active at the same time will the sample pixel move 10+10=20 points?

The answer is no. The reason is that whatever adjustment happens second is not starting at the 210 pixel value. It's starting at the 220 pixel value created by the first adjusment. If Eric is correct, the Curves is happening after the Exposure.

Redcrown,

I just want to add or clarify....

It is not the order you use the controls that matters.  It is that the controls have a fixed sequence in which they are executed.  Therefore it is usually better to apply them in the same sequence.  Either way, it should be expected that further tweaking may be needed as you go along.
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John

EricV

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #8 on: October 30, 2015, 07:32:17 pm »

It is not the order you use the controls that matters.  It is that the controls have a fixed sequence in which they are executed. 
  Yes.  This means that if multiple sliders are changed, the final result is completely specified by the values of the sliders.

Therefore it is usually better to apply them in the same sequence.
  I do not see how this follows at all.  If I end up with the same slider settings, the sequence does not matter.  Is the implication that if I adjust exposure first and contrast second, I am likely to end up with a different (better) final set of slider settings?  Or perhaps I will get to the same slider settings, but with less back-and-forth tweaking along the way?
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mouse

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #9 on: October 30, 2015, 11:11:41 pm »

Thanks. I like his tutorials, but don't really want / shouldn't need to pay for what I would hope was just factual info. Any alternatives?

+10 for Jardine's tutorials.  You are better off paying (very little) for good factual information presented in very lucid fashion than relying on random (but free) speculation from a variety of self proclaimed experts.
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Peter_DL

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #10 on: November 02, 2015, 07:57:22 pm »

Eric claims that the ACR adjustments "interact", and should be used, in the way they are layed out in the UI. Top down and left to right. So, Basic adjustments first, Curves second, Detail third, etc. Within Basic, Exposure first, Contrast second, etc. There is one key exception to this, and that is Camera Calibration (profile) which is applied before anything else.

Exposure, Contrast, Whites, and Blacks are all just curves of different shapes (bell, arc, slant, S). Even Clarity is kind of an S-Curve applied with an edge mask. Highlights and Shadows adjustments are very different beasts. They are not curves. They have evolved to use some very complicated and unique logic. Google "Laplacian Filters" for a fun read about that.

well summarized.

It may further be worth to mention that the Exposure control is covered by the PV2012's autohighlight recovery, an intended feature to emulate the gentle highlight rolloff that film provides (as noted by Eric Chan). Unlike the Whites control, or a Whitepoint setting via the Curves tab (point curve), which transition straight into clipping but offer a better tonal separation of the non-clipped highlight details.


This means that if multiple sliders are changed, the final result is completely specified by the values of the sliders. I do not see how this follows at all.  If I end up with the same slider settings, the sequence does not matter.

Following are two related quotes from Eric Chan (iirc from the Adobe forums),
however, even though Eric is The engineer it should be mentioned that there are other philosophies i.e. Whites/Blacks first not last.

>>the results depend only on the numbers themselves, not the order in which you set the numbers. But the interaction of the controls may feel weird if you use the controls out of order.<<
>>The ranges and behavior of Whites/Blacks controls depend on how the earlier controls are set (one reason why working top-down is generally recommended). If you set Whites/Blacks earlier, this can result in interaction problems if you then go back up to the earlier sliders (e.g. Shadows).<<


Peter
--
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mouse

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Re: How do the basic settings, contrast and the tone curve interact?
« Reply #11 on: November 13, 2015, 03:45:07 pm »

Is there a pointer to a good tutorial on how the different tone settings interact?

It is clear how the basic settings work, shifting different parts of the tone curve.  But then we have contrast, which compresses or stretches the tonal range.  And then we have the tonal curve.  The default medium/strong contrast curves drop the shadows.  So there are clearly links between the different sliders.

Now, it may be that there are just different ways of achieving the same transformation of the original tonal curve, but there may be some subtle differences.  Can anyone explain them?

Have a look here; the video and the downloadable pdf file..   It is a brilliant way to visualize how all the settings in ACR Photoshop interact.
« Last Edit: November 14, 2015, 01:56:32 am by mouse »
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