How can I configure a profile to use the linear tone curve that is associated with a raw file?

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I would like to create profiles for my cameras that have a true linear tone curve. i.e. no embedded adjustments for highlights and shadows from the straight line that is characteristic of a raw file linear tone curve.

When I made camera profiles with the DNG Profile editor there was an option for a linear tone curve along with the Adobe standard tone curve.
When testing the profile creation capabilities of the new version of LR and ACR it seems that there is some "below the surface" adjustments made to the linear tone curve. i.e. pulling down highlights via slider or decreasing shadow density via the slide does add more detail to the highlights and shadows. This suggests that there are adjustments baked into the software that deviate from a straight line tone curve.
So, A) are there deviations? B) if so, how can they be removed?

Thanks,
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David Ward

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Posted 2 weeks ago

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DP HOME

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even if you are using just a simple matrix profile with explicitly embedded linear (0.0,0.0 - 1.0, 1.0) curve ACR code will still work in a non linear fashion around clipping - which you can mitigate somewhat by selecting prev. process version like v2010

content of dcp profiles can be examined (and modified) using dcptool ( dcptool.sourceforge.net )
(Edited)
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David Ward

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That's what I am trying to find out; what has to be changed to get ACR to handle it in a linear fashion.I know about going to earlier process version, but have no idea what else that impacts so would prefer to stay away from that option.
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DP HOME

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code behaviour (based on Process version used for example) and/or content of all profiles used... again - if you have to use ACR and have to be sure - use simple matrix DCP camera profile alone with explicitly embedded linear curve and proper process version... if you are using process v2012 you can't get linear behaviour around clipping (and even not around it),  so forget it... C1 for example has a special flag in .fcrv files (curves data) that will switch on/off special handling around clipping... but if you are fine with non linearity from the code then simply embed linear curves in your profiles explicitly
(Edited)
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Todd Shaner, Champion

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What's your target "end-use" or objective for the linear raw file conversion? Here's a fully linear raw converter that you can download and use for free. This is useful for processing color negative film.

http://www.colorperfect.com/MakeTiff/
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David Ward

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There are times when I want to start the processing from a file with all the tonal and color detail that the camera was able to get into the raw file without any hidden manipulation.Could be documenting art work, doing an architecture job with lots of sun and deep shadows, or even shooting models in studio.
I paid a lot of money for the cameras and I'd prefer to be the one making choices about tonality rather than an engineer at Adobe.
My workflow is built around Lightroom and Photoshop for a number of reasons. So don't really want to use a specialized raw converter. I prefer the parametric approach that LR uses offering multiple processing treatments of the same base file.
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The best suggestion I can offer is to change your Default Develop Settings for Highlights from 0 to -50 and Shadows from 0 to +50. You may find a lower setting works better like -25 and +25, but I suggest keeping them opposite and equal.

You'll need to change the settings for each camera model with a raw file selected. Hit the Reset button at the bottom of the Develop controls panel. Next select the desired camera profile, adjust Highlights and Shadows as suggested. Then hold down the ALT key and click on the Reset button again and click on 'Update to Current Settings.'
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David Ward

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Todd,
That's what I've been doing for years.What I'm looking for now, since Adobe has added the Profile module is a way to build profiles that can be easily applied while importing the files into Lightroom with the sliders then able to optimally fine tune the file.

Here are three screen captures of a file to illustrate how Lightroom impacts the file differently based on the underlying tone curve and camera profile.

All settings were left at Zero or the same value except for the highlight, shadow, white and black point. All three files have the same tone curve applied. Its the Adobe steep curve with + and - 15 added. Here is the tone curve as applied. 

This one is with the profile set to Adobe color;


This one is with the profile set to the profile I created for GFX using DNG Profile editor and the standard Adobe tone curve. The profile was placed into the profile module by Lightroom when it updated to the latest version.

This one is with the profile set to the profile I created for GFX using DNG Profile editor and the linear curve option. I then created a profile following the process described in the SDK PDF file. The 4 at the end means its using the Version 4 processing.I made adjustments using exposure and highlight/shadow sliders to adapt a Macbeth color chart gray scale during the process. I used the same Macbeth image file with Version 2 processing applied as the basis for the adjustments.


It may be hard to see without having the files at full size, but the detail in the bright area and clouds are much more detailed and subtle in this last example.
I think I've got a useful camera profile for the GFX-50s but without any empirical data about whats going on. And its a pain to have to go through this process for every camera.
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Todd Shaner, Champion

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So you want to create dcp camera profiles with a linear tone curve and then use the new XMP profile tools to piggyback custom Tone controls and Tone Curve settings correct? Sounds like a good idea to me, but I haven't worked with the new profile creation tools yet in ACR 10.3. Someone else landing here may be able to help. I suggest also posting your question in the Camera Raw forum. It may get more attention there: https://forums.adobe.com/community/cameraraw

One "piggyback" concern I would like to point out is that all of the Develop controls have limits. For example if you apply global Tone panel  -50 Highlights and then use the local Adjustment Brush to add more -Highlights the maximum effect will be Global + Local = -100. I'm fairly certain this same limit applies to when using the new XMP camera profiles. The sum of all three control settings (XMP Profile, Global, Local) will have an effective limit of the control's min and max settings (i.e. Highlights ±100).

UPDATE: I just tested the above described limit by creating a new XMP camera profile in ACR 10.3 containing -100 Highlights and +100 Shadows. When the camera profile is applied to an image file the Basic panel -Highlights setting has no effect and the same for a +Shadows setting (i.e. at max 100 limit). This confirms what I stated above and should be taken into consideration when processing image files so you don't get unexpected results.
(Edited)
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DP HOME

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>  I prefer the parametric approach

all raw converters are parametric ...
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David Ward

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They are until the settings are baked into an output file.
I want to go from Lightroom to Photoshop so that I can use smart object capabilities to continue to refine the parametric settings.
Working with TIFFs from a raw converter means that Photoshop is starting with baked in processing from the raw converter.