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

[dmward255]

I asked this question in another forum on the Adobe site and it was suggested I also post it here.

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?

[descender]

I had a similar question last week, right after the same Camera Raw and PS and LR CC update went out.

I was finding that there didn't seem to be any existing profile, even the Adobe Neutral one, that was truly neutral, zeroed, and linear. When I opened Camera Raw as a smart filter applying to a smart object image layer in PS, the image was immediately, visibly affected, before I even chose a profile, and even explicitly choosing Adobe Neutral and checking that all sliders in all control sections were neutral/zero/linear, I could not get back to zero alteration of the image. It really seemed as though merely opening Camera Raw as a filter was applying something "below the surface", as you say, that I couldn't find any option to avoid.

This was really confusing me and I wasn't finding any solution after asking and searching and even contacting support. Finally, by chance I also noticed that Scrubby Zoom had become disabled for no apparent reason after the same Adobe updates. In pursuing that, I turned off every option in PS > Edit Preferences > Performance and turned back on just the ones that I always use, closing out in between and restarting the program. This did not look like it ought to help, since the Performance prefs showed that I was indeed using GPU acceleration and OpenGL was enabled. But in the spirit of "just reset stuff and hope" I tried what I tried anyway. I ended up getting Scrubby Zoom back on my next restart of Photoshop, and after that point I no longer saw images tweaked by merely opening a new Camera Raw smart filter with no settings made.

What I'm describing follows different lines than your stated issue but seems like it could possibly be closely related. In short, maybe you need to break your LR or PS's connection to your graphics card and then reinstate it. I am hypothesizing that doing so "burps" something we can't see in the OpenGL and/or OpenCL environment and gets things running correctly.

Best of luck in any case.

[2Pop]

Hello,

Not sure on how you create your linear profile but, to my knowledge, DNG profile editor is for editing files not creating them. I use DCP and ICC profle files that I have created (shooting color target and creating profile) and I ended up with true linar response curve when using in ACR or Lightroom

[savage08]

here! https://trentsizemore.com/blog/using-a-linear-camera-calibration-profile/

[xx Zoki xx]

As the name suggests, the mentioned app creates and edits profiles. It has the capability to create a linear profile.

[PECourtejoie]

Hello, I'm surprised, it is not explained in the SDK? Digital Negative (DNG), Adobe DNG Converter | Adobe Photoshop CC

[D Fosse]

dmward255  wrote

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.

This assumption seems flawed to me. Rather, this is a characteristic of shooting raw in general. This is why we shoot raw in the first place. There is always more information available in a 14 bit raw file with a dynamic range of ten or twelve stops - than can be reproduced in a gamma encoded RGB file. That's the whole point.

I don't have the technical background to document this, but my gut feeling is that this is what they call a red herring. It's not where the meat is.