The GoProTune LUT pack consists of over 110+ LUTs spanning the Native, WIDE (GoPro Labs firmware) and Rec.709 source color gamuts and various output Gammas in order to provide support across a large spectrum of workflows. The LUT Pack includes Lookup Tables supporting Natural, Protune Flat and the newly developed GP-Log for HERO12 Black cameras.
This LUT Pack has been specifically developed due to a lack of proper technical transforms available for GoPro Protune footage. Version 2.5 of the LUT Pack includes support for Natural and the updated GP-Log in addition to camera specific LUTs that have calculated using the mean color values across HERO9 Black up to the HERO12 Black for a consolidated series of supported LUTs. A series of Legacy LUTs are also included for GoPro HERO8 and earlier cameras.
The pack includes a number of output variations with the following specifics:
- Technical Transform LUTs with output to P3 D65 or Rec.709 Scene
- Technical Transform LUTs with output to P3 D65 or Rec.709 Gamma 2.2
- Technical Transform LUTs with output to P3 D65 or Rec.709 Gamma 2.4
- A series Output LUTs that add +1, +2 and +3 stop exposure adjustments with proper Tone and Gamut mapping output to Rec.709 for either TV (Broadcast) or Web scenarios.
- A series of HDR LUTs with +2 and +3 stop exposure adjustments with output to 1000 nit PQ ST2084 HDR or HLG HDR
There is a general lack of information with regards to the Protune and GP-Log Gamma curves as well as the Native Color Gamut parameters. Whilst the Protune curve is considered an SDR curve, it can also be useful in HDR workflows as up to 3+ stops can be recovered in ideal scenarios without significantly visible noise.
Shown below is a Characteristic Curve of the Protune Gamma with the curve also under-exposed by 1, 2 and 3 stops respectively.
For reference, the table on the right identifies the IRE values that Protune can be exposed to with reference to an 18% Middle Gray card. Shown are the standard Protune curve as well as the IRE values when under-exposing by 1, 2 and 3 stops respectively.
|Protune – 1 EV
|Protune – 2 EV
|Protune – 3 EV
The GP-Log Curve is essentially a modified version of the Protune Flat curve but uses a base value of 400 instead of the standard 113. Prior to HERO12 Firmware 1.20, GP-Log was also deliberately under-exposed by 2 stops in-camera to provide highlight detail preservation. Whilst the updated iteration of GP-Log uses 0EV exposure compensation, the Log format can be under-exposed between -1EV to -2EV. This under-exposure allows GP-Log to easily fit in with a number of HDR workflows where highlight preservation is key. Middle-Gray is 49% IRE for the original GP-Log (which was -2EV under-exposed) and 76% IRE for the newer version of GP-Log at 0EV.
The LUTs should be copied to the designated LUT folder hierarchy of your desired Application or Monitoring System. This will vary from one application and Recorder/Monitor to another.
Depending on the target application, the LUTs may need to be copied to some of the following folders on Windows based systems:
- C:\ProgramData\Blackmagic Design\DaVinci Resolve\Support\LUT\
- C:\Program Files\Adobe\Common\LUTs\Creative
- C:\Program Files\Adobe\Common\LUTs\Technical
Depending on the target application, the LUTs may need to be copied to some of the following folders on Mac OS systems:
- /Library/Application Support/Blackmagic Design/DaVinci Resolve/LUT
- /Library/Application Support/Adobe/Common/LUTs/Creative
- /Library/Application Support/Adobe/Common/LUTs/Technical
Depending on the target application, the LUTs may need to be copied to some of the following folders on Linux systems:
File & Folder Structure
For better usability, the LUT files have been sorted into distinct folders. The first folder hierarchy consists of Native, WIDE and Rec.709 color gamut folders.
Native is when the White Balance is set to Native under camera settings. The color gamut is limited to Rec.709 when the camera is set to any White Balance value other than Native. If using WIDE=1 in GoPro Labs firmware, the camera can use Automatic White Balancing along with a Native color gamut.
The next sub-folder hierarchy consists of Output Gamma settings. Gamma 2.2 is used for Web/Display, Gamma 2.4 is used for TV/Broadcast, HDR is for PG or HLG output, Scene is for ITU-R BT.709 Scene referred workflows and Tone Mapped LUTs consist of tone and gamut mapped LUTs for direct TV/Broadcast or Web/Display outputs.
The File structure is generally as follows:
<Curve Type>_<GoPro Color Gamut>_<Possible Exposure Adjustment>_<Output Color Space>_<Output Gamma>
As an example, let’s look at the following file name:
- The Curve Type is Protune Flat
- The GoPro Color Space is Native
- The Exposure adjustment is +3 stops correction for clips that have been 3 stops under-exposed in camera.
- The Output Color Space is Rec.709 (which is tone mapped down)
- The Output Gamma is a Tone-Mapped instance of Gamma 2.2 for Web/Displays
The Technical LUTs provide a base conversion, from which additional color grading and tweaking can be done. On the other hand, when the Tone Mapped Output LUT is selected, no further color grading or tweaking is required as this will map the color and dynamic range to cover the output gamut and output levels accordingly.
GoPro Protune and GP-Log footage is always encoded using Data levels (0 – 255). Where applicable, ensure Full Data levels are explicitly set in the clip attributes.
Due to the Protune curve’s overall high value of 68% IRE for middle gray and relatively great dynamic range for the sensor size, most footage can generally be under-exposed by 1-2 stops with an adjustment made in post to recover the midtones and expand the highlights. The Tone Mapped LUTs are therefore included in +1, +2 and +3 EV increments.
Similarly, when middle gray is under-exposed by 2 stops at 37% IRE, the Protune curve provides nearly 4.5 stops of highlight latitude relative to the under-exposed mid-gray. This is particularly useful in HDR workflows and the HDR LUTs have also been provided to allow for a direct HDR conversion to either PQ or HLG.
The GP-Log curve is already under-exposed by 2 stops allowing for nearly 4.5 stops of highlight latitude above middle gray. The Tone Mapped LUTs therefore include GP-Log with the default exposure and a +1 EV increment for anything that is slightly more under-exposed.
Importantly, the auto multi-metering used by GoPro cameras has a tendency to under-expose shots by up to -2 EV in order to preserve highlights. For scenes with varying exposures, this could mean that the whole frame is shot under-exposed. If shots appear darker, consider adding an exposure adjustment of between 0.5 to 2 stops after the LUT or using the Tone Mapped LUTs with built-in exposure adjustments such as a +1 EV Tone Mapped LUT.