Houdini 19.0 Nodes Compositing nodes Color Correct

Color Correct compositing node

Applies a variety of color corrections to the image

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This operation applies a variety of color corrections to the image, and these can be independently controlled for the shadow, mid-tone and highlight regions of the image.

The Shadow, Midtone and Highlight adjustments are applied first, and then the Master controls are applied.

The individual adjustments are:

  1. Gamma

  2. Multiply (brightness)

  3. Add

  4. Contrast

They are applied in that order.


This operation may be restricted to certain planes, or components of planes. In addition, the operation may be applied to a subset of frames within the sequence. An image must have both its frame and plane scoped to be modified.

Images that are not modified are passed through, which does not take any memory or processing time.


This operation may be masked, which restricts the operation to an area of the image. The mask may be inverted, brightened or dimmed.

The mask input is on the side of the node. The label on the connector indicates the plane being used as a mask.

The mask input can also be scaled to fit the output image’s resolution, if they differ. If this node is changing constantly, and the mask is not, it is somewhat faster to put a Scale COP down to do the resize for the mask image. Otherwise, the scale will occur every time this node cooks.

Collapsible Pixel Operation

This is a collapsible pixel operation. When placed in sequence with other collapsible pixel operations, the operations are combined into one operation at the final node in the pixel operation sequence. This is known as a collapsible pixel operation chain.

Image data flowing through the chain is only quantized at the end of the chain. This allows the intermediate operations to produce and carry values outside the normal range of the pixels' data format, with floating point precision. The net result of this is a reduction in quantization error and black/white clipping (especially useful for integer formats).

Collapsible pixel operations are recognizable by the light blue background color of the node’s icon. If a node of a different color is inserted between two collapsible COPs, the chain will be broken at that point and the operations will not collapse anymore.

Collapsible pixel operations are maskable and scopable. If one operation in the chain is masked, but the others are not (or do not share the same mask), the chain will be 'broken' at that point and quantization will occur at that node. Differences in scoping does not cause a break in the chain.



This set of controls is applied on the entire range of color.


The color to add or subtract the image.


Multiplies the image by the color (similar to brightness).


Adjusts the gamma of the image.


Adjusts the contrast of the image; 1 is normal contrast.


This set of controls have the same functions as above, but only apply to the low (shadow) areas of the image.


This set of controls adjusts the mid-tone areas.


This set of controls adjusts the highlights.

Show Color Curves

Pops up a viewer showing the color curves applied to the image.

Collapsible Pixel Operation Parameters

Collapsible pixel operations can be combined with other collapsible pixel operations and have the result computed in one pass, rather than at each node. The operations must be in sequence, without other nodes between them.

Do Operation in Unpremultiplied Space

The Color plane will the divided by the input alpha, and multiplied by the output alpha so that the color operation is done in unpremultiplied space. If this operation is in a collapsible chain, all the nodes in the chain must have the same setting of this parameter to avoid breaking the chain and quantizing.


If this node is in the middle of a collapsible pixel chain, you can force this node to quantize and store the images at this node.


A mask can be chosen to limit the effect of the operator to areas defined by the mask. The mask can be taken from the mask input (side input) or from the first input itself.

Effect Amount

If no mask is present, this blends the output with the input by a constant amount (0 = all input, 1 = all output).

If a mask is present, this amount multiplies the mask.

Operation Mask

Selects the mask plane to use as a mask from the mask input. The mask can be selected from:

A mask can be a component of a plane or an entire plane. If a vector plane is supplied as a mask, its components are multiplied by the images' components.

Scalar Mask ('A', 'C.r')

C.r = I.r * M
C.g = I.g * M
C.b = I.b * M

Vector Mask ('C')

C.r = I.r * M.r
C.g = I.g * M.g
C.b = I.b * M.b

First Input

Useful for masking the operation to the image’s own alpha plane.

Mask Input

Selects the mask from the side mask input.


Turns off masking, without requiring disconnection of the mask input (useful for temporarily disabling the mask).

Resize Mask to Fit Image

If the mask image is a different resolution than the output image, turning on this parameter will scale the mask to the output image’s resolution.

If this node is changing constantly, and the mask is not, it is somewhat faster to put a Scale COP down to do the resize for the mask image. Otherwise, the scale will occur every time this node cooks.

Invert Mask

Inverts the mask so that all fully 'masked' portions become unmasked. This saves you from inserting an Invert COP after the node with the mask.


Plane Scope

Specifies the scope for both the RGB components of Color, Alpha, and other planes. The (C)RGBA mask only affects Color components and Alpha. 'C' will toggle all the RGB components.

For planes other than Color and Alpha, the plane name (plus component, if applicable) should be specified in the string field. The pulldown menu can be used to select planes or components present in this node.

A plane is specified by its name. A component is specified by both its plane and component name. The '*' wildcard may be used to scope all extra planes. Any number of planes or components can be specified, separated by spaces.


N.x N.y
P N Pz

Frame Scope

Frame Scope

Allows scoping of specific frames in the frame range. This is in addition to the plane scope (so a plane at a certain frame must be both plane scoped and frame scoped to be modified).

All Frames

All frames are scoped.

Inside Range

All frames inside a subrange are scoped.

Outside Range

All frames outside a subrange are scoped.

Even Frames

Even numbered frames are scoped.

Odd Frames

Odd numbered frames are scoped.

Specific Frames

A user-defined list of frames are scoped.

Frame Range

For Inside/Outside range, this parameter specifies the subrange of the sequence to scope (or unscope). This can be edited in Timeline viewer mode (⌃ Ctrl + 2 in viewer).

Frame Dropoff

For Inside/Outside Range, this parameter specifies certain number of frames before and after to slowly ramp up to scoped. The operation will be blended with its input to 'ease in' or 'ease out' the scoping effect over a number of frames. This can be edited in Timeline viewer mode (⌃ Ctrl + 2 in viewer).

Non-scoped Effect

For unscoped frames, this sets the blend factor between the input and modified images. Normally this is zero (use the input image). By setting this to a non-zero value, you can make unscoped frames be 'slightly' unscoped. The value can vary between 0 (unscoped) and 1 (scoped).

Frame List

The frame list for 'Specific Frames'. Frame numbers should be separated by spaces.

Automatically Adjust for Length Changes

If the sequence range changes, enabling this parameter will adjust the subrange and frame dropoff lengths to fit the new range.



Sequence length


Start of sequence


End of sequence


Input sequence length


Sequence frame rate


Number of planes in sequence


Width and height of image


Image index (0 at start frame)


Image time (0 at start frame)


Current plane array index


Current plane index


Num of channels in current plane


Composite Project X resolution


Composite Project Y resolution


Composite Project pixel aspect ratio


Composite Project raster depth


Composite Project black point


Composite Project white point

See also

Color Correct