Camera Raw: Color Space in Camera Raw Profiles created with .CUBE file

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I've not been able to find any information about creating profiles in Camera Raw using the .CUBE lookup table option "Space." It defaults to sRGB. Why? It's not the way the lookup table was created, since I created one in PS in ProPhoto RGB on a file that had been opened from CR as  ProPhoto RGB.  Is there some advantage to sRGB? Is there some disadvantage to choosing another color space?

If there's no disadvantage to using ProPhoto RGB (and it does turn off Clip which seems desirable often enough), then why isn't my default color space in Camera Raw automatically assigned? If that's not feasible because of some way these things are constructed, then why can't my settings in the dialog be sticky, at least if I choose that as a workspace Preference? Nothing is sticky in that dialog, so it's an awful lot of mousing about when generating more than one profile from a set of .CUBE files.
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Cristen Gillespie

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Posted 1 month ago

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Andrew Rodney

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All processing is happening in ProPhoto primaries (gamut) and 1.0 TRC. Always. There's no assigning anything in LR or ACR. You render the image and tell both what working space you want, that's what you get. Now I don't have a clue about creating .CUBE profiles and why you see sRGB but none the less, the underlying raw (and rendered) color space is that unnamed ProPhoto RGB/1.0 color space. 
There's no advantage to sRGB other than considering it an output color space to post images to the web and mobile devices. That's it. 
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Max Wendt, Employee

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The .CUBE file format does not include a color space specification; when you export from Photoshop, the resulting LUT has no indication that it is ProPhoto. That's why you need to specify it manually.
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Cameron Rad

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I would love if there was a simple tool to visualize and generate the CSV Look table files.

Something like a web app or something that would generate an image of unwrapped table/grid of swatches based on the look table parameters (limiting to the max amount allowed) and then allowing the user to select on one or a range of value and adjust the HSV/HSL parameters. Then allowing you to export that into a csv. I don't know anything about coding but am trying to learn so I can try to make something like this. 

Also I much appreciate the help and work you and the ACR team have done with this. I love using the 3DLUT enhanced profiles. I currently am experimenting with creating logarithmic DNG profiles and combining them with Film Print Emulation 3DLUTs. It's definitely fun to play around with and would love to learn how to do more. :)
(Edited)
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Cristen Gillespie

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> when you export from Photoshop, the resulting LUT has no indication that it is ProPhoto. That's why you need to specify it manually.>

Thanks for replying. Okay, that it doesn't know what color space it was created confirms what I saw when I experimented with it, but that makes me ask, then, why do you choose sRGB as the default — each and every time? Why DO I have to specify it manually? Why can't I set the defaults for this dialog, or have what I set be sticky?  It's a lot of defaults that I have to alter/uncheck.

If, as Andrew points out, sRGB doesn't have any advantage here, and I will want ProPhoto RGB as my output from CR, so why must I be stuck with sRGB?

We're all in love with Profiles now, as you can see from the message right above mine, so I'm afraid you'll get stuck with a lot of us asking for more features.<G>
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Cameron Rad

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sRGB is a good default. It's the ISO standard default for desktop computing and is fairly universally adopted at this point. https://www.w3.org/Graphics/Color/sRGB.html

Nuke and a lot of VFX apps as well as non-colormanaged applications default to assuming sRGB. I think for compatibility, ease of use, etc sRGB is a good default. Maybe with an option for Rec709 for basic users. More advanced users can use the other spaces and create their LUTs for those color spaces. In most cases you will find LUTs designed for Rec709 or DCIP3. Rec709 and sRGB are the same except for gamma. I think it would be useful for Adobe to have the option of Rec709 2.4 as well, so there isn't any gamma adjustment needed or gamma rendering issues.

Because ProphotoRGB isn't a common color space used in most LUTs, i don't think it'd serve well as a default color space. I think the people that want to use ProphotoRGB would have no issue selecting it as an option as they'd already have to do additional work making luts for it.
(Edited)
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Cristen Gillespie

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Okay. I understand that LUTs were originally for the video crowd if they were created in that space, it makes sense to keep them there—I suppose. I may be showing my ignorance there.

So why can't the dialog be sticky? Other dialogs/panel settings are. If I set things a certain way, why not hold it that way until I change things? If I've unchecked any of the panel settings, why not leave them unchecked. If I've switched to ProPhoto RGB, why not leave it there? If I'm in a specific set, why not have that set be the one I'm adding to. The SDK even suggests we put our own LUTs in our own set, but it's never selected. I have to select it manually each time.

And yes, I am doing the additional work of making LUTs, as well as modifying those I brought in and saved (manually) as profiles. That's half the fun of it. <s>

Thank you for answering my question as to why sRGB is the default. That at least answers half my question.
(Edited)
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Cameron Rad

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Yea I totally get you on the sticky thing, that's a good suggestion. I modify my LUTs for ProphotoRGB and have made quite a few.  I definitely have run into issues where I forget to select a parameter and either built the LUT with wrong color space or put it in wrong set.