N-Log Transform Manual

Nikon N-Log Transform

Preamble

The N-Log Transform has been developed due to the absence of a Nikon N-Log ACES IDT in DaVinci Resolve. The N-Log Transform consists of ACES IDTs for Nikon N-Log as well as the N-Log Transform DCTL for all workflows (ACES and DaVinci YRGB).

Prerequisites

The DaVinci Color Transform Language (DCTL) files are compatible with DaVinci Resolve 16 and above. They are meant to be used as an Input Transform (IDT) for content recorded using Nikon N-Log and are especially targeted for ACES workflows as well as DaVinci YRGB Color Managed and Non-Color-Managed workflows. The DCTLs will work in DaVinci Resolve Studio and DaVinci Resolve Free. Note that the Free version of Resolve may display a watermark for anything outside of the ACES IDTs due to DCTL feature limitations.

Installation

There are two N-Log DCTL files that need to be installed. Their specifics are described in the table below.

TransformDescription
N-Log TransformTransform with all options and modifiable parameters
N-LogACES IDT

These transforms are included in a LUT and IDT folder. The relevant files must be copied to the designated folder hierarchy as described below.

Windows

On Windows, the files within the LUT folder must be copied to the following directory:

C:\ProgramData\Blackmagic Design\DaVinci Resolve\Support\LUT\

The files within the IDT folder must be copied to the following directory:

%APPDATA%\Blackmagic Design\DaVinci Resolve\Support\ACES Transforms\IDT\

MacOS

On MacOS, the files within the LUT folder must be copied to the following directory:

/Library/Application Support/Blackmagic Design/DaVinci Resolve/LUT/

The files within the IDT folder must be copied to the following directory:

~/Library/Application Support/Blackmagic Design/DaVinci Resolve/ACES Transforms/IDT/

Linux

On Linux, the files within the LUT folder must be copied to the following directory:

/home/resolve/LUT/

The files within the IDT folder must be copied to the following directory:

~/.local/share/DaVinciResolve/ACES Transforms/IDT/

Usage

As of Resolve 17, there are two main ways to use the N-Log Transform:

  1. As an ACES Input Transform (IDT)
  2. Through Resolve’s Node structure using the DCTL ResolveFX Plugin

Note: Only the N-Log Transform DCTL has parameters that can be manipulated. The other DCTL file is a streamlined transform for use directly as an ACES Input Transform (IDT) through the ACEScc and ACEScct Color Science options.

ACES Input Transform Method

This feature set is only available in Resolve 17 and above. The N-Log IDT can be selected at the Project Level or via the ACES Transforms plugin. As of Resolve 17.2, the N-Log IDT can also be selected at the individual clip level via the ACES Input Transform selection. This is the preferred way of selecting the N-Log IDT for ACES.

Resolve’s DCTL Plugin Method

In order to use this method, the relevant DCTL will need to be selected through the DCTL OpenFX Plugin. Any Input Color Space or ACES Input Transform will need to be explicitly disabled at the clip level. It’s also recommended to have this as the first node in the structure.

Usage Parameters

The default parameters allow the transforms to be used within an ACES workflow. Some use cases may require operation from within the DCTL OpenFX plugin in order to manipulate the available parameters/modifiers.

The sections below will outline the parameters available and sample workflows.

Exposure Correction

The Exposure Correction Parameter allows for exposure adjustment in Exposure Values (EV) from -8 to +8. The values can be manipulated using the slider or by inputting the EV directly in the designated field. Source footage that is either over-exposed or under-exposed can be corrected this way.

Color Science

The selection of Color Science is important as it dictates the transform behavior. The default Color Science is ACEScc/ACEScct to allow for usage within ACES workflows. Select DaVinci YRGB when using YRGB or YRGB Color Managed modes.

Use Whitepoint Adaptation

This checkbox allows for automatic whitepoint conversion and is enabled by default. It is specifically geared for DaVinci YRGB when using ACES settings inside a YRGB Color Managed workflow.

Deselecting this will mean the ACES AP0 and AP1 color spaces use a D65 whitepoint instead of their native ~D60.

This parameter should align with the whitepoint adaptation settings defined at the project level.

Timeline Color Space

This setting will convert the source to the desired color space, normally aligning with the Timeline Color Space in Resolve.

The Color Space Options are:

  • ACES AP0
  • ACES AP1
  • P3 (D65)
  • Rec. 709 (D65)
  • BT. 2020 (D65)
  • DaVinci Wide Gamut

ACES AP1 is the color space associated with ACEScc, ACEScct and ACEScg. ACES AP0 consists of the ACES 2065-1 color primaries and is the default color space to allow for direct usage as an IDT within ACES workflows.

Timeline Gamma

This setting will convert the source to the desired Gamma, normally aligning with the Timeline Gamma settings in Resolve.

The Gamma Options are:

  • Linear
  • ACEScc
  • ACEScct
  • Scene (ITU-R BT.709)
  • Gamma 2.2
  • Gamma 2.4
  • Gamma 2.6
  • DaVinci Intermediate
  • sRGB

The default Gamma is Linear to allow for direct usage as an IDT within ACES workflows.

User Workflows

ACEScc or ACEScct

The Transform can be used directly within the ACEScc / ACEScct Color Science workflow as an IDT or through the Node structure for manipulation of additional parameters.

To use the transforms as an IDT in Resolve 17 and above, simply select N-Log under the ACES Input Transforms. Alternatively, the N-Log Transform can be loaded for individual clips. In Resolve 16 and below, the DCTLs can be found under the DaVinci CTL sub-menu. In Resolve 17 and above, the DCTLs are now found under the LUT sub-menu and pane on the Color page. For this method, any Input Transforms must first be bypassed either within the project settings, or within the clip. Once all Input Transforms have been removed from the desired clips, simply right click the required clip(s) and select the desired transform.

If parameter manipulation is required in ACES, the N-Log Transform.dctle transform can be used in the Node structure through the DCTL OpenFX plugin. The transform’s Timeline Color Space MUST be set to ACES AP0 and the Timeline Gamma must be either ACEScc or ACEScct.

DaVinci YRGB & YRGB Color Managed

The following workflows only apply to the N-Log Transform. All other DCTL files are specific to the ACEScc/ACEScct Color Science workflows and should not be used here.

When working in DaVinci YRGB and YRGB Color Managed Color Science modes, it’s recommended to use the DCTL from within the Node Structure through Resolve’s DCTL OpenFX plugin. The Color Science settings within the DCTL should be set to DaVinci YRGB and ensure the DCTL Timeline Color Space and Timeline Gamma match the settings of the project appropriately. Where possible, any Input DRT should be disabled to avoid unwarranted Tone and Gamut mapping. In a Color Managed workflow, these parameters will be dependent on the project Timeline color settings. In Non-Color Managed workflow, these will be dependent on the Output color settings.

In Resolve 16 and below, unless otherwise modified, the default option is Rec.709 for Timeline Color Space and Gamma 2.4 for Timeline Gamma.

In Resolve 17 and above, the default option is Rec.709 for Timeline Color Space and either Gamma 2.4 or Scene for Timeline Gamma, depending on project settings.

As of Resolve 17, the Color Management settings have been overly simplified to the detriment of accuracy. The Input DRT setting is now automatically set to DaVinci. It’s recommended to explicitly disable this option by changing the Project color settings to Custom and disabling the Input DRT.

ACES (DaVinci YRGB)

The recommended method to use the transform with ACES inside a YRGB Color Managed workflow is to set the Project Timeline Color Space as ACES and bypass the Input Color Space both in the Project settings and on the individual clips. The transform can then be selected through Resolve’s DCTL OpenFX plugin. By default, the Color Space and Gamma are set to ACES and Linear respectively.