OCIOLookTransform

OCIOLookTransform applies a creative colorspace transform using a predefined look in the OCIO config file. A look is a named color transform intended to modify the 'look' of an image in a creative way, rather than a technically or mathematically defined colorspace conversion. Examples of looks include a neutral grade applied to film scans prior to VFX work and per-shot digital intermediate (DI) grades required by the director's vision applied before a Viewer transform, such as rec1886.

OCIOLooks are predefined in OCIO config files before use and often reference per-shot or per-sequence LUTs or color corrections (CC). See https://opencolorio.org/ for more information on look configuration examples.

Note: There are a number of NDK examples covering OCIO workflows that ship with the Nuke developer documentation, which can be found here:
<install_directory>/Documentation/NDKExamples/Plugins/00b_8source.html

Inputs and Controls

Connection Type	Connection Name	Function
Input	unnamed	The image sequence to receive the colorspace conversion.
mask	An optional image to use as a mask. By default, the colorspace conversion is limited to the non-black areas of the mask. At first, the mask input appears as a triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Connection Type

Connection Name

Function

Input

unnamed

The image sequence to receive the colorspace conversion.

mask

An optional image to use as a mask. By default, the colorspace conversion is limited to the non-black areas of the mask.

At first, the mask input appears as a triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Control (UI)	Knob (Scripting)	Default Value	Function
OCIOLookTransform Tab
channels	channels	rgb	The colorspace conversion is applied only to these channels. If you set this to something other than all or none, you can use the checkboxes on the right to select individual channels.
input	in_colorspace	scene_linear (linear)	Specifies the input colorspace. Note: The control label has been updated, but the knob name currently remains the same. The knob name will also change in a future release.
look	look	N/A	Specifies the look to apply as defined in the OCIO config file. You can specify a single look or multiple looks using the following syntax: • Multiple looks are combined with , (comma): 'a,b' • Direction is specified with +/- prefixes for forward and inverse: '+a, -b' • Missing look fallbacks are specified with \| (pipe): 'a, -b, \| -b' Note: ACES 1.3 OCIO configs include a Reference Gamut Compression look designed to correct wide gamut errors. This is the only look defined in the ACES 1.3 OCIO configs that ship with Nuke, so it is applied automatically. If more than one look is defined in the config, you can pick the look to apply using the look dropdown.
reload	reload	N/A	Click to reload all files used in the specified look(s).
invert direction	invert	disabled	Select invert direction to invert the transform.
output	out_colorspace	scene_linear (linear)	Specifies the output colorspace to which the input is converted. Note: The control label has been updated, but the knob name currently remains the same. The knob name will also change in a future release.
ignore errors	ignore_errors	disabled	When enabled, transforms that cannot locate a look defined in the OCIO config file are treated as a normal colorspace conversion from the input to the output colorspaces specified.
mask	N/A	disabled	Enables the associated mask channel to the right. Disabling this checkbox is the same as setting the channel to none.
mask	maskChannelInput	none	The channel to use as a mask. By default, the colorspace conversion is limited to the non-black areas of this channel.
inject	inject	disabled	Copies the mask input to the predefined mask.a channel. Injecting the mask allows you to use the same mask further downstream.
invert	invert_mask	disabled	Inverts the use of the mask channel so that the colorspace conversion is limited to the non-white areas of the mask.
fringe	fringe	disabled	When enabled, only apply the effect to the edge of the mask. When disabled, the effect is applied to the entire mask.
(un)premult by	N/A	disabled	Enables the associated channel to the right. Disabling this checkbox is the same as setting the channel to none.
(un)premult by	unpremult	none	The image is divided by this channel before being processed, and multiplied again afterwards. If you are using premultiplied input images, you may want to check (un)premult by and select rgba.alpha here. This will simulate doing the color conversion before the premultiplication was done. It is the same as adding an Unpremult node before this node and a Premult node after, but allows you to work faster if you’re only using one color correct node. If you are using unpremultiplied input images, you should leave this set to none.
invert	invert_unpremult	disabled	Inverts the use of the (un)premultiply channel.
mix	mix	1	Dissolves between the original image at 0 and the full colorspace conversion at 1.
Context Tab
key1	key1	n/a	Allows you to add variables to register certain viewer processes by creating a custom config.ocio and specifying the variable in the to_reference file transform. See Adding Context Viewer Processes for more information.
value1	value1	n/a
key2	key2	n/a
value2	value2	n/a
key3	key3	n/a
value3	value3	n/a
key4	key4	n/a
value4	value4	n/a