UNDERSTANDING THE TRANSFORM
The standard X-H2SFuji2Alexa transform is divided into two components, the camera match transform and the output transform.
The first component or transform matches the cameras in linear space and outputs the image in log. It takes F-Log2 footage from the X-H2S as the input, linearises the image, matches it to the Alexa, then outputs this match as ARRI LogC/Alexa Wide Gamut.
The second component is an output transform LUT that takes the ARRI LogC/Alexa Wide Gamut image and converts it to Rec709. This takes the flat desaturated log image, applies a LogC to Rec709 2.4 gamma curve, an Alexa Wide Gamut to Rec709 matrix and outputs an image with restored contrast and saturation that will look correct on your display.
WHY TWO TRANSFORMS?
The main reason is so that footage converted with X-H2SFuji2Alexa can be integrated into existing colour grading workflows designed for the Alexa, or so that it can integrate alongside footage from the Alexa allowing the same look to be applied to both sets of footage with little or no modifications.
The key component of X-H2SFuji2Alexa is the camera match transform. This is actually where the “Alexa look” lives. The output transform, while important, isn’t actually a large part of what gives the Alexa its distinctive look. In most Alexa productions, the default ARRI Rec709 output transform LUT used in camera, is discarded when it comes to grading. And all grading is carried out on the ARRI LogC/Alexa Wide Gamut image. Therefore using just the first component of X-H2SFuji2Alexa places the X-H2S footage at an equal start point to real Alexa footage. From this point the X-H2S footage can be treated as if it was real Alexa footage. Any grade, PowerGrade, look or LUT designed for the Alexa can now be used on the X-H2S footage with little or no modification.
WHEN YOU MIGHT WANT TO USE A SINGLE COMBINED TRANSFORM
In some situations or workflows it might be necessary to use a single combined transform. A combined transform is useful for previewing the look on-set via a LUT as it would be impractical and unnecessary to use two transforms at this stage. It can also be useful to use a combined LUT at the edit stage so you can work with a more finished looking image. Combined in-camera/on-set LUTs can be found in the X-H2SFuji2Alexa Rec709 In-Camera and On-Set LUTs folder. If you purchased the LUT version of X-H2SFuji2Alexa, high quality combined LUTs for post production can be found in the X-H2SFuji2Alexa Rec709 Post-Production folder.
IMPROVING THE STANDARD ARRI REC709 OUTPUT TRANSFORM
While the standard ARRI Rec709 LUT is probably the best of all camera manufacturer LUTs, it can still be improved on. As part of 2Alexa I have made some modifications to the standard ARRI LUT. These new LUTs have been modified for a more finished look with more filmic saturation. They were born from my research into film emulation. They allow for deeper, richer colours whilst avoiding over-saturation. The new LUT is called ARRI_LogC2Video_709_V2.cube. And a lower contrast wide dynamic range version is called ARRI_LogC2Video_709_WDR_V2.cube
CAMERA SIDE SETUP
As mentioned above, X-H2SFuji2Alexa expects F-Log2 as the input. Below are the recommended camera settings.
Gamma/Gamut: F-Log2
ISO: Use whatever ISO setting you need to achieve correct exposure.
Temp/Tint: Use whatever temp and tint you need to achieve the correct white balance. I find that the X-H2S is a little cool and a fraction magenta compared to the Alexa, so for daylight scenes I use 5700K. The in-camera tint setting is not fine enough to remove the magenta tint, so I leave it as the default.
Codec: I recommend using the highest quality codec that works with your media, frame rate and bit rate combination.
INSTALLATION AND USAGE
IN-CAMERA AND MONITOR LUTS
The in-camera and monitor LUTs can be found in the X-H2SFuji2Alexa Rec709 In-Camera and On-Set LUTs folder. Currently the X-H2S does not support internal LUTs, so LUTs need to be applied via an external monitor.
LUT VERSION RESOLVE INSTALLATION
Extract the zip file, open Resolve and bring up Project Settings. Navigate to the Color Management tab on the left and find the Lookup Tables section. Click the Open LUT folder and copy over the X-H2SFuji2Alexa LUT folder. If you also want the all-in-one Rec709 versions you can also copy the X-H2SFuji2Alexa Rec709 Post-Production folder as well. Navigate back to Resolve and click the Update Lists button. The LUTs will now be accessible inside Resolve.
RESOLVE COLOR MANAGEMENT SETUP
In the Color Management tab make sure the Color Science is set to the default of Davinci YRGB and the Timeline color space is set to Rec.709 Gamma 2.4. If you’re on a Mac and usually set your timeline colour space to Rec709-A, leave the Timeline color space as Rec709 Gamma 2.4 and set Rec709-A as the gamma tag in the delivery page.
USING THE LUTS IN RESOLVE
This is the basic node structure I recommend for the LUTs.
Node 01 is noise reduction. Whether noise reduction is needed depends on the footage. Normally I use NeatVideo, but Resolve’s noise reduction is actually very good. When using Resolve’s 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 3.0-8.0.
Node 02 place the X-H2SFuji2Alexa_LogC_V1.cube camera match transform LUT in this node. Avoid making any changes prior to this node as it will affect the accuracy of the camera match transform.
Node 03 is used for image balancing, generally using the offset colour wheel, offset master wheel and contrast/pivot. The idea here is to balance the image and correct for shot to shot differences. For colour balancing use the offset colour wheel. Use the master offset wheel (slider under the offset colour wheel) for exposure changes and use contrast and pivot to dial in the contrast for your image. Working in this node and onwards is the same as working on real Alexa footage.
The gap between Node 03 and 04 this is where creative grading takes place. You can use any tool or technique here. Use whatever is needed to achieve the look you are after.
Node 04 is used for the output transform LUT. This node handles the conversion of ARRI LogC/Alexa Wide Gamut to Rec709. Select a LUT from the X-H2SFuji2Alexa/Alexa Rec709 folder or any other LUT designed for ARRI LogC. You can also use a Colour Space Transform node in place of this node to handle the conversion for extra flexibility. Or you can remove this node completely and append one of my YRGB print film emulation PowerGrades.
USING THE LUTS WITH OTHER SOFTWARE
The are two methods to use the X-H2SFuji2Alexa LUT transforms in NLEs such as Adobe Premiere.
The easiest method is to use the all-in-one LUTs included with the LUT version of X-H2SFuji2Alexa. Apply one of the LUTS from the X-H2SFuji2Alexa Rec709 Post-Production folder, then grade underneath this LUT. The way I would set this up in Premiere is to create an Adjustment Layer that sits over the entire timeline. Add a Lumetri effect to the Adjustment Layer and select one of the all-in-one LUTs. Add another Lumetri effect to any clip that needs grading/correction. Corrections to each clip are now happening under the main Adjustment Layer LUT.
The second method is slightly more involved but it’s more accurate and closer to working with real Alexa footage. It It also gives you more flexibility as you can choose to use any output transform LUT made for the Alexa. The way to set this up in Premiere is to apply a Lumetri effect to a clip, then in the Input LUT field select the X-H2SFuji2Alexa_LogC_V1.cube LUT from the X-H2SFuji2Alexa/X-H2SFuji2Alexa LogC folder. Then copy this Lumetri effect to every clip in your timeline. Create an Adjustment Layer that sits over the entire timeline, add a Lumetri effect to it and select any LUT from the X-H2SFuji2Alexa/Alexa Rec709 folder. You can also select any LUT made for the Alexa. Any corrections made to the Lumetri effect at the clip level are happening under the main Adjustment Layer LUT.
POWERGRADE INSTALLATION AND USAGE
POWERGRADE INSTALLATION
To install the PowerGrades in Resolve, navigate to the PowerGrade 1 stills album in the Gallery. Adding PowerGrades to this album will allow you to access the PowerGrades from any project and it will also mean you only have to import them once. Once the album is selected, second mouse button click in the gallery window background pane and select Import. Navigate to the extracted zip file location and select the .drx file(s) 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 .drx from the list, then try again.
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 X-H2SFuji2Alexa 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 X-H2SFuji2Alexa YRGB POWERGRADE
Once installed, the PowerGrades can be applied to the selected shot by middle mouse button clicking on the thumbnail still in the gallery. Or with a second mouse button click on the thumbnail and then selecting Apply Grade from the menu.
This is the structure of the PowerGrade.
Node 01 corrects the individual RGB channels via the RGB curves.
Node 02 is a custom curve that converts F-Log2 to F-Log as F-Log2 is not currently supported by Resolve’s CST. There is no loss of dynamic range in this conversion. I’ll release a new version of the PowerGrade when Resolve supports F-Log2.
Node 03 is a CST node that transforms F-Log to linear.
Node 04 is the 3x3 matrix and the core of the camera match transform. This matrix lives in the RGB mixer and it aligns the X-H2S colours to match the Alexa.
Node 05 is for accurate exposure adjustments using the master gain wheel (the slider under the main gain colour wheel). Doubling the gain from 1.00 to 2.00, 2.00 to 4.00 etc increases the exposure by precisely 1 stop. It doesn’t need to be whole rounded values, any value that is doubled is an increase of one stop. In the same way halving from 1.00 to 0.50, 0.50 to 0.25 etc decreases the exposure by 1 stop. And again it’s any value, not just whole rounded values. You can also colour balance in this node by using the gain colour wheel, which results in more accurate and cleaner results than using the offset wheel and sometimes even better results than the temp/tint controls when working with raw footage. Do not use any tool other than master gain wheel and colour gain wheel in this node as it will produce incorrect results.
Node 06 is a CST that transforms the image from linear into ARRI LogC. If you have any colours that are clipping or causing out of gamut issues, try enabling Gamut Mapping in the CST in this node.
Node 07 houses hue v hue/sat/luma custom curves that add extra accuracy to the camera match. Due to the non linear response of the sensor, it is not possible to fully match it to the Alexa with just a 3x3 matrix. This node is the final node of the camera match transform.
The Gap between Node 07 and 08 is where creative grading takes place. You can use any tool or technique to achieve the look you are after. Grading at this point is the same as grading real Alexa footage.
Node 08 is the output transform. It handles the conversion from ARRI LogC/Alexa Wide Gamut to Rec709. This node can be replaced with any LUT in the folder. Or any other LUT designed for ARRI LogC. You can also use a Colour Space Transform node in place of this node to handle the conversion for extra flexibility. Or you can remove this node completely and append one of my many YRGB print film emulation PowerGrades.
Much the same as the LUT version, avoid making any adjustments prior to the first node as this will affect the transform’s accuracy.
Following my standard Alexa workflow, for most grades I remove Node 08 and replace it with a Print Film Emulation (PFE). Either a real PFE LUT or one of my PFE PowerGrade rebuilds.
With or without the PFE, all grading should take places after Node 07 but before the output transform.
Similar to the LUT version of the PowerGrade, I pretty much always add noise reduction in a node before Node 01. I mostly use NeatVideo, but I sometimes use Resolve’s noise reduction. For noise reduction settings check the LUT section above.
X-H2sFuji2ALEXA RCM POWERGRADES
The RCM version of X-H2SFuji2Alexa will be released soon.
QUESTIONS, COMMENTS, SUPPORT
For questions, comments or if you need LUT/PowerGrade support feel free to contact me at support@juanmelara.com.au