ColorLookup

Allows you to make contrast, gamma, gain, and offset adjustments (and, in fact, many others) using lookup tables (LUTs). LUTs refer to line graphs of a given color channel’s brightness. The horizontal axis represents the channel’s original, or input, values, and the vertical axis represents the channel’s new, or output values.

Inputs and Controls

Connection Type	Connection Name	Function
Input	unnamed	The image sequence to color correct.
mask	An optional image to use as a mask. By default, the color correction is limited to the non-black areas of the mask. At first, the mask input appears as 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 color correct.

mask

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

At first, the mask input appears as 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
ColorLookup Tab
channels	channels	rgba	The color correction is only applied to these channels. You can use the checkboxes on the right to select individual channels.
use precomputed table	use_precomputed	enabled	When enabled, ColorLookup uses a precomputed lookup table (LUT) between 0 and the value specified in the range field to increase processing speed.
range	range	1	Sets the precomputed LUT search range between 0 and this value to increase processing speed.
curve editor	lut	N/A	You can use the lookup curves to edit the range of the image in individual channels, or ganged using the master curve (which represents all channels). To edit one curve with reference to another, select multiple curves. You can look up color information for the current pixel in the Viewer. Drag the cursor over the pixels you want to sample for the correction. In the ColorLookup curve editor, press Ctrl/Cmd+Alt while clicking on the curve to set points at the places where the red, green, and blue lines intersect with the color curve. Edit the position of the points and adjust the tangent handles to adjust the curve shape for the color correction.
reset	N/A	N/A	Returns the selected curve(s) to the default values.
source	source	0	Sets a source color for adding points to the curve editor.
target	target	0	Sets a destination color for adding points to the curve editor.
Set RGB	setRGB	N/A	Adds points on the r, g, and b curves, mapping source to target. You can use this control to match shadow, midtone, and highlights on two plates, for example. Set source to shadow rgb in one, target to shadow rgb in the other, then press Set RGB. Same for midtone and highlight areas.
Set RGBA	setRGBA	N/A	Adds points on the r, g, b, and alpha curves, mapping source to target.
Set A	setA	N/A	Adds points on the alpha curve, mapping source to target.
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 color correction 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 color correction 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 correction 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 color correction at 1.

Step-by-Step Guides

Using ColorLookup Curves