A number of Panasonic Lumix GH5 owners using Final Cut Pro X with LUT loading plug-ins have reported varying LUT interpretation results with 8-bit and 10-bit footage. The problem involves clamping or lowering the footage superwhites after LUTs have been applied.
High whites are well-preserved in GH5 V-Log 10-bit 4:2:2 footage with Leeming LUT One applied in Premiere Pro, before and after
The most common problem reportedly does not appear in Adobe’s Premiere Pro NLE using the Lumetri Color panel, but seems to be centred on Apple’s Final Cut Pro X or more specifically some current versions of third party LUT-loading plug-ins.
So far the specific causes of this problem, and its permanent solution, have not been 100% identified, but it may be useful to share a list of the free and paid-for LUT plug-ins and related software that are currently available. If the cause resides in one or more specific LUT plug-ins, then it may be wise to try out others on the list below.
Meanwhile Premiere Pro itself has some problems with correctly supporting 8-bit and 10-bit GH5 footage and Blackmagic’s DaVinci Resolve colour grading software-cum-NLE also seems to incorrectly clamp super whites after LUTs have been applied.
LUT and colour grading plug-ins, and applications
- Chromatic – currently undergoing development, CoreMelt’s Chromatic color grading plug-in is their “all in one color grading plugin that combines curves, color wheels, tracked masks, inside-outside mask grades, selective color correction, LUT loading and management and degrain, regrain all in one tool.”
- Color Finale and Color Finale Pro – colour grading plug-in suite with LUT loading capability, made by Denver Riddle of Color Grading Central.
- Epicolor – intriguing new product by Lemke Software, available through FxFactory, includes a post production LUT application feature.
- FxFactory – retails a catalog of plug-ins and effects for Final Cut Pro X and other NLEs including colour grading plug-ins.
- FCPX LUT Loader – free plug-in for Macs running macOS Sierra and later, made by FCPX plug-ins specialist Pixel Film Studios, which offers a number of LUT looks packs for purchase.
- LUT Buddy – free LUT loader plug-in by Red Giant, formerly available as a separate download but now included in Red Giant’s Magic Bullet Suite 13, available in a trial version.
- LUT Gallery – according to maker Denver Riddle of Color Grading Central, the “most powerful way to do color grading with LUTs! Includes Auto WB Color Picker”.
- LUT Utility – by Color Grading Central, also maker of Color Finale.
- LUTx – FCPX plug-ins maker CoreMelt states that LUTx is “the most powerful LUT solution for Final Cut Pro X” and retails a number of looks LUT collections.
- mLUT – free LUT loading plug-in by motionVFX, retailer of a range of looks LUT packages.
- ScopeBox – professional scopes application for macOS computers, that allows feeding video from a range of DIT tools and Adobe video software as well as Final Cut Pro X into ScopeBox via ScopeLink. ScopeBox maker divergent media says that “the scopes found in most desktop editing applications leave a lot to be desired – they’re not accurate, they’re slow, and they’re not configurable”.
The crux of the problem and a workaround
Paul Leeming of Leeming LUT One describes the problem as follows. The LUTs from his unified, corrective LUT system are “designed to maximize dynamic range, fix skin tones, remove unwanted colour casts and provide an accurate Rec. 709 starting point for further creative colour grading”.
The Leeming LUT One system provides “the best possible settings to maximise dynamic range and image quality for that camera, while minimising noise and other unwanted artefacts”. Thus the system’s LUTs are “designed to work with the full float levels of the video clips as they come out of camera”.
“Some cameras stop at 100 IRE, but others such as Panasonic and Sony retain superwhite up to 109 IRE (usually), so my LUTs are designed around that limit, not the 100 IRE limit,” Mr Leeming says.
He offers one potential workaround, until LUT plug-ins are updated to support float space. “The easiest temporary solution is to adjust IRE for clips to fall within 0-100 IRE, then apply the LUT, as in theory the distribution of values in float space should be the same. That should avoid clipping”.
Mr Leeming notes that he designs Leeming LUT One in Premiere Pro which “handles superwhites with the LUT directly” and “no need to pull down exposure” and was “not aware that there were programs which didn’t pull down superwhites or lift superblacks”.
A more permanent solution
Roger Bolton of CoreMelt, developer of Chromatic and LUTx, has further insights into the problem and its solution:
A LUT is defined in the color ranges 0-1 in float with 1 being defined as the highest legal level (100 IRE). You can stretch the LUT out to handle the additional levels but that’s changing the look of the LUT if it was designed on legal levels. There’s not really a “correct” solution that I’m aware of, so how a LUT loader should handle this is something that needs flexibility.
As Chromatic is currently under development, Mr Bolton says that “we plan to allow a few different ways of dealing with the issue” and has asked users to send him their requests. He states that LUTx will be updated to handle superwhites and Chromatic will also handle them when released.
- Apple – Customize your workflow. Perfect your projects with an array of ingenious plug-ins, devices, and content
- digital films – Greater LUT Control with Koji Advance
- digital films – Hawaiki Color