Camera Raw: Add Rec 709 to LUT color spaces in new enhanced profiles

  • 14
  • Idea
  • Updated 10 months ago
  • Under Consideration
The new enhanced profiles can include LUTs, but the most common color space for existing LUTs, Rec 709, is omitted: 



There are thousands of Rec 709 LUTs available for video color grading, and allowing Rec 709 LUTs in enhanced profiles would let people achieve the same look for their video and still images.

Note that it would be necessary to include two versions of Rec 709 for gamma 2.2 and 2.4, since those are both widely used.
Photo of John R. Ellis

John R. Ellis, Champion

  • 4368 Posts
  • 1160 Reply Likes

Posted 1 year ago

  • 14
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Where are you accessing that screen capture? 
Photo of John R. Ellis

John R. Ellis, Champion

  • 4310 Posts
  • 1142 Reply Likes
In the New Profile dialog of ACR 10.3, which you get to by holding down Opt / Alt and clicking the New Preset button in the Presets tab.
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
But what are you loading there? It's grayed out until you load something right? 
Photo of John R. Ellis

John R. Ellis, Champion

  • 4310 Posts
  • 1142 Reply Likes
I loaded a LUT in .cube format.  Once it was loaded, then the Space dropdown menu was active.
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
I get that, but why then select one of the RGB working space options above? 
Photo of John R. Ellis

John R. Ellis, Champion

  • 4310 Posts
  • 1142 Reply Likes
"Space" specifies the color space of the LUT. The .cube LUT format doesn't specify the LUT's space, so you've got to tell ACR what it is.
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Ah, good to known, thanks. So what happens if the color space isn't in sync? That is, you pick sRGB or ProPhoto but you want Rec 709? Like with ICC profiles, does that screw up the color appearance? And if you use such a LUT, does one have to use them only on images that are in the same color space (seems that wouldn’t be necessary with raws that have to be encoded into something at some point). 
Photo of John R. Ellis

John R. Ellis, Champion

  • 4310 Posts
  • 1142 Reply Likes
"So what happens if the color space isn't in sync? That is, you pick sRGB or ProPhoto but you want Rec 709? Like with ICC profiles, does that screw up the color appearance?"

Yup.  

sRGB is pretty close to Rec 709, with the same primaries but modestly differently gamma encoding.  A Rec 709 LUT applied to an sRGB image will often / usually result in an image acceptably close to that LUT applied to the Rec 709 version of the image, though I can often see differences in the shadows, as you'd expect.

"if you use such a LUT, does one have to use them only on images that are in the same color space (seems that wouldn’t be necessary with raws that have to be encoded into something at some point)."

No, the enhanced profile containing the LUT can be applied to any image that ACR / LR can read.  Looking at the profile's .xmp file, the color space isn't recorded anywhere, just an encoded LUT.  I'm guessing that encoded LUT represents the specified LUT, converted to the working space of ACR (MelissaRGB).
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Very interesting, thanks!
Obviously I need to dig into LUT's and creation a lot more know that we have such features in ACR/LR. I'm toying with buying 3D LUT Creator; are you familiar with it and if so, is the entry level ($99) version sufficient? 
TIA.
Photo of John R. Ellis

John R. Ellis, Champion

  • 4310 Posts
  • 1142 Reply Likes
I don't have any experience with 3D LUT Creator.  I've used Lattice a little for technical transforms of LUTs. 
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Thanks, interesting video's on Lattice. I have to see if the $99 version of 3D LUT creator is going to cut it for starting out or, their Standard version which is on par price wise with Lattice:
https://3dlutcreator.com
Photo of Cameron Rad

Cameron Rad

  • 5 Posts
  • 0 Reply Likes
Andrew, if you're comfortable with command look into this. From the creator of Lattice.

https://github.com/gregcotten/pylut

https://www.jasonmyres.com/converting-3d-luts-for-resolve-lustre-and-nuke-using-pylut-in-osx
(Edited)
Photo of Cameron Rad

Cameron Rad

  • 5 Posts
  • 0 Reply Likes
Also Lattice isn't a WYSIWYG freeform LUT editor like 3DLUTCreator. By that I mean it's not such that one can select a range of colors and modify them. It's more a GUI for LUT math. Similar to LUTcalc https://cameramanben.github.io/LUTCalc/LUTCalc/index.html but in my opinion far more intuitive and provides a bit more options. 
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Thanks ; more and more, 3DLUT creator seems like the best option for me.
Photo of John R. Ellis

John R. Ellis, Champion

  • 4368 Posts
  • 1160 Reply Likes
As an indication of the need for Rec 709, this LR feature request for the ability to use LUTs in LR has 97 votes:
https://feedback.photoshop.com/photoshop_family/topics/id_love_to_get_the_ability_to_use_3d_luts_in_...
Photo of Cameron Rad

Cameron Rad

  • 5 Posts
  • 0 Reply Likes
I agree. I commented on Julieanne Kost's blog post about it as well. http://blogs.adobe.com/jkost/2018/04/lightroom-cc.html

Copy/Pasting my comment from the post:

Question about the LUTs in the SDK. In regards to Space and Clip/Extend. What specifically is this referring to? The RGB data being input, output?

For instance if I have a LUT that converts Rec709 Gamut/sRGB Gamma -> Rec709/Cineon > Kodak 2383/Rec709 Emulation would I select space: srgb/clip?

Basically do I need to make my LUT loop back into whatever colorspace I define in ACR? For instance ProphotoRGB/Gamma 1.8 -> Rec709/Cineon -> Kodak2383/Rec709 Emulation -> ProphotoRGB/Gamma 1.8.

How does ACR/LR interpret the RGB data after it’s run through the LUT?

I assume it has to process the data from LR Internal working space > some RGB > LUT > Interpret RGB DATA > Convert for display icc.

I feel like it’d be useful to add a couple parameters that define how to encode the RGB data going into the LUT and another for how to interpret the output data from the LUT. A few standard ones can be:

LUT Input Space (This is the data fed into the LUT/Exported out of ACR):

Rec709/Cineon Log
Rec709/sRGB
Rec709/Gamma 2.4
Rec709/Rec709 Gamma
P3D65/Gamma 2.6
P3D60/Gamma 2.6
P3D65/sRGB (DisplayP3)
ACESCG/Gamma 1.0
ProphotoRGB/Gamma 1.0
ProphotoRGB/Gamma 1.8
ProphotoRGB/sRGB

LUT Output Space(This is the data fed out of the LUT/Interpreted by ACR):

AdobeRGB/Gamma 2.2
Rec709/sRGB
Rec709/Gamma 2.4
Rec709/Gamma 2.2
Rec2020/Gamma 2.4
P3D65/Gamma 2.6
P3DCI/Gamma 2.6
P3D60/Gamma 2.6
P3D65/sRGB (DisplayP3)
ProphotoRGB/Gamma 1.8
ProphotoRGB/sRGB

Thanks so much!
(Edited)
Photo of John R. Ellis

John R. Ellis, Champion

  • 4368 Posts
  • 1160 Reply Likes
The color space specified by Space refers to the color space on which the LUT is defined to operate.  So if you select Rec 2020, then the LUT will be assumed to take as input color numbers in Rec 2020 and produce as output color numbers in Rec 2020.

I believe that internally, ACR transforms that LUT to operate on color numbers in the internal working space of ACR (Melissa RGB, a variant of ProPhoto RGB). But I haven't verified that yet.
Photo of Cameron Rad

Cameron Rad

  • 5 Posts
  • 0 Reply Likes
I figured it out. Some LUTs are used as color space transforms, so it's likely best to use Prophoto RGB as the operating space to prevent clipping.

Round trip example with ProphotoRGB selected using Lattice to create LUT:

Prophoto RGB  > REC709/Cineon > Kodak 2383 DCIP3 >  Prophoto RGB. 

Also with Lattice make sure "Preserve Embedded Color Space Profiles" is checked in the preferences. 
(Edited)
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Minor point: Melissa RGB which is a variant of ProPhoto RGB has a 2.2 TRC but isn't the internal color space for processing which has no name and has a 1.0 TRC. Melissa RGB is only used for the RGB values and Histogram (when no soft proof profile is selected as in LR). 
Photo of Cameron Rad

Cameron Rad

  • 5 Posts
  • 0 Reply Likes
Hi Andrew,

Do you know if it's 2.2 or sRGB? The TRCs are very slightly different, linear section near bottom part.

The reason I ask is in the enhanced profile documentation it states there are two encodings for profile look tables, 0=Linear and 1=sRGB
Photo of John R. Ellis

John R. Ellis, Champion

  • 4368 Posts
  • 1160 Reply Likes
"Melissa RGB which is a variant of ProPhoto RGB has a 2.2 TRC but isn't the internal color space for processing which has no name and has a 1.0 TRC."

Right, thanks for the correction.
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Just the same sRGB TRC of 2.2, not a simple gamma curve.
Photo of Andrew Rodney

Andrew Rodney

  • 761 Posts
  • 149 Reply Likes
Better yet: Think of it as sRGB with ProPhoto RGB primaries.
Photo of John R. Ellis

John R. Ellis, Champion

  • 4368 Posts
  • 1160 Reply Likes
Any chance of getting this in the next version of Camera Raw? This would make it possible to use the thousands of LUTs available in Rec 709, and make it much easier for people producing videos and stills to use LUTs to achieve consistent looks.

 Isn't it a trivial change to add two more ICC profiles?  
Photo of Vanni Tagliavento

Vanni Tagliavento

  • 1 Post
  • 0 Reply Likes
Any news guys?