LUT INSTALLATION AND USAGE
RESOLVE LUT INSTALLATION
Extract the zip file, open Resolve and bring up Project Settings. Navigate to the Color Management tab on the left and scroll down to Lookup Tables. Click the Open LUT folder and copy over the G2URSA2Alexa folder. If you also want the all-in-one Rec709 versions you can copy the G2URSA2Alexa Rec709 Post-Production folder as well. Navigate back to Resolve and click the Update Lists button. The LUTs will now be accessible inside Resolve.
IN-CAMERA LUT INSTALLATION
The in-camera LUTs can be found in the G2URSA2Alexa Rec709 In-Camera and On-Set LUTs folder. LUT installation instructions can be found on page 124 in the URSA Mini Pro Manual.
USING THE LUTS IN RESOLVE
This is the basic node structure I use with the LUT.
Node 01 is noise reduction. I generally use Spatial NR with Mode set to Faster, Radius set to Small. Then under Spatial Threshold I unlink Luma and Chroma and leave Luma at 0.0 and set Chroma to around 8.0.
Node 02 is the G2URSA2Alexa_LogC_InputScale transform LUT.
Node 03 is used for fine tuning the image balance, generally using contrast/pivot and offset. The idea here is to correct for shot to shot differences as the overall balance is best handled in the raw tab. If the footage is Prores, the bulk of the balancing will take place in this node. This balance node placement is different to the PxK2Alexa transforms as G2URSA2Alexa does some very precise corrections to the RGB channels. The less you do prior to the LUT, the more accurate the conversion. I would limit any pre LUT adjustments to just temperature and tint.
The gap between Node 03 and 04 this is where creative grading takes place.
Node 04 is the output LUT. This node handles the conversion of ARRI LogC to Rec709. Select a LUT from the Alexa Rec709 folder or any other LUT designed for ARRI LogC. You can also use a Color Space Transform node to handle the conversion for extra flexibility.
USING THE LUTS IN PREMIERE PRO
There are two methods to use the LUTs in Premiere Pro.
The first and easiest method is to add an Adjustment Layer over the entire timeline then add a Lumetri effect and apply a LUT from the G2URSA2Alexa Rec709 Post-Production folder. You can then add a Lumetri effect on any clip that needs any specific corrections beyond the raw tab.
The second method also requires an Adjustment Layer and a Lumetri effect, but this time add a LUT from the G2URSA2Alexa / Alexa Rec709 folder. These LUTs convert Alexa LogC to Rec709. However, they don’t contain the G2URSA2Alexa transform component in them like the Post-Production LUTs in the first method. Therefore each clip will need its own G2URSA2Alexa_LogC LUT applied to each clip via another Lumetri effect.
One of the issues with Premiere Pro is that effects like Lumetri lose access to any information that exceeds the top of the waveform. This information is clipped and can’t be recovered by any process within Lumetri. Unfortunately the brightest highlights in ISO800 URSA footage decoded as BMDFilm gamma exceed the top of the waveform. To get around this limitation I created the G2URSA2Alexa_LogC_Premiere LUT. To use this LUT select ACEScct gamma in the raw tab. ACEScct gamma is a flatter curve that prevents information from exceeding the top of the waveform. The LUT then handles the conversion from ACEScct to BMDFilm then applies the G2URSA2Alexa conversion and outputs LogC ready for the Rec709 LUT in the Adjustment Layer above. You can then make any adjustments in the same Lumetri effect but only if they happen after the LUT. Which I believe is the case if you use the Input LUT slot in Lumetri.
For the most accurate results I would recommend always decoding at ISO800. This is due to the precise corrections that G2URSA2Alexa applies at specific luminance levels. I would do any exposure corrections in the Lumetri effect so they take place after the G2URSA2Alexa corrections.
POWERGRADE INSTALLATION AND USAGE
POWERGRADE INSTALLATION
To install the PowerGrade in Resolve, in the Gallery tab navigate to the PowerGrade 1 stills album. Adding the PowerGrade to this album will allow you to access the PowerGrade from any project and it also means you only have to add it once. Once selected second mouse button click in the gallery window background and select Import. Navigate to the directory where the zip file was extracted and select the .dpx file and click import. If it doesn’t let you select a file, you might need to click the options button at the bottom of the import window and then select .dpx or .drx from the list, then try again.
Once installed the PowerGrade can be applied to the selected shot by middle mouse button clicking on the still in the gallery. Or with a second mouse button click and then selecting Apply Grade.
Along with the PowerGrade you’ll need to install the ARRI LogC to Rec709 conversion LUTs. Follow the LUT installation instructions above and copy the G2URSA2Alexa Rec709 LUTs folder to Resolve’s LUT folder. If you do this incorrectly, your footage will remain as flat log gamma after applying the PowerGrade. You will also get a missing LUT error message.
USING THE POWERGRADE
This is the structure of the PowerGrade node graph. I will update this section with detailed instructions in the next couple of days.
Much the same as LUT version, avoid making any adjustments prior to the first node as this will affect the transform’s accuracy. Limit any pre LUT adjustments to just temperature and tint. I would also stick to ISO800 and use the gain wheel in the Exposure Node 04 to do accurate fully corrected exposure adjustments. Any other corrections or creative grading should take place after Node 05.