Houdini 20.0 Nodes Compositing nodes

VEX Generator compositing node

Runs a VEX script on the planes it generates.

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This COP runs a VEX script on the planes it generates. The vex script should not read from R,G,B,A, C1,C2,C3 or C4. The vex script should write to C1, C2, C3 and C4 (components 1 to 4 of each vector).

This COP node is a generator.


VEX Generate

VEX Function

The VEX script to run, with any parameter arguments you wish to override.

Reload VEX Functions

Reloads the VEX script. Useful if the script has been modified and re-compiled.


The mask parameters control the mask applied when a node is connected to the mask input. The Effect Amount parameter is always available, whether a mask is connected or not.

Effect Amount

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

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

Mask Plane

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

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.


Parameters relating to the structure of the image generated, including Resolution, Pixel Aspect Ratio and Raster Depth.

Override Size

If off, the resolution of the image is defined by the resolution in the Composite Project settings. If on, any resolution can be specified.

Pixel Aspect Ratio

If off, the pixel aspect ratio of the image is defined by the pixel aspect ratio in the Composite Project settings. If on, any pixel aspect ratio can be specified.

The pixel aspect ratio determines the shape of the pixel; it represents the width of the pixel compared to the height. A pixel with an aspect ratio of '2' is twice as wide as it is high (2:1). Pixel aspect ratios less than 1 are taller than they are wide.

The image viewer attempts to show the image as it would appear by horizontally scaling the image by the pixel aspect ratio. This can result in slight artifacts for non-integer ratios (ie, 0.9:1, 1.442:1). Turn off 'Fast Pixel Aspect' in the Display Options to suppress these artifacts.

Many effect filters that have parameters that represent width and height will have the width scaled appropriately (such as Blur, Defocus, Expand).

Image Planes

Specifies the plane(s) to generate. Color and Alpha will always be present, but the generator does not always have to write to them.

The list of planes is all the ones Houdini recognizes as special. Other planes can be added with the 'Custom Planes' parameter.

C, A (C:rgb A)

Color and Alpha

C, A (C:rgb A:rgb)

Color and 3-channel Alpha

C (rgb)

Color only


Alpha only

A (rgb)

3-channel Alpha only


Mask plane

M (rgb)

3-channel Mask plane


Z Depth plane


Luminance plane

B (uv)

Bump plane

P (xyz)

Point plane

N (xyz)

Normal plane

V (xyz)

Velocity plane


No planes generated.

Add Plane

When a generator is connected to an input, it generates a Mask plane by default. This parameter determines which planes are generated in this case. The list of planes to generate are the same as 'Image Planes'.

In addition, if the plane already exists in the input sequence, one of the following operations will be performed to combine the new plane.


Input plane replaced by the generated plane. (G)


Generated plane renamed.


Input plane added to the generated plane. (I+G)


Input plane photographically added to the generated plane. (I+G-I*G)


Generated plane subtracted from the input plane. (I-G).


Input plane multiplied by the generated plane. (IxG)


Minimum pixel value of input and generated planes. (min{I,G})


Maximum pixel value of input and generated planes. (max{I,G})


Average pixel value of the input and generated planes. (I+G)/2

Custom Planes

This string parameter allows you to create your own plane formats. The syntax is:


All parts are optional except for planename. arraysize must be 1 or greater (default 1). comp1 to comp4 are arbitrary strings representing the component names. format is either i8, i16, i32, f16 or f32. black and white are integers representing the black & white points for integer formats.

Raster Depth

The byte format of the image. Higher bit depths provide better color resolution and range at the expense of memory.

8 Bit Integer

Lowest bit depth. Banding can occasionally be seen. Suitable for video.

16 Bit Integer

Intermediate bit depth. No banding can be seen, though clipping can still occur below and above the black and white points.

32 Bit Integer

Generally not used for color, 32bit integer values are used to store object IDs, counts, and other integer values with a large range.

16 Bit Floating Point

High bit depth. No banding can be seen, and no clipping occurs at white and black. Uses less memory than 32 bit float, however processing time for this format is slightly higher as it is not a native CPU data format. This format supports values in the range -65504 to +65504.

32 Bit Floating Point

High bit depth. No banding can be seen, and no clipping occurs at white and black. Uses 4× as much memory as 8bit, which is this format’s main drawback.

Default Depth

Use the raster depth specified in the Composite Project options.

Black/White Points

The integer formats (8, 16 and 32 bit) can specify the raw values that the black and white points occur at. The white point must always be higher than the black point. The minimum and maximum values for the black and white points for each format are:

8 bit : 0 - 255
16 bit : 0 - 65535
32 bit : 0 - 2,147,483,647

Floating point formats always have their black point at 0 and their white point at 1.


Controls the ability to generate images that are compatible with interlaced images.

If you are manipulating the generated output with a filter that uses neighboring pixels (like Blur or Expand), it is recommended that you do not use Black Interlaced, as the filter will use the black scanlines as well.

The second menu determines which scanlines are in which fields (odd,even)


No interlacing.

Half Res Interlaced

The image is half the height of a normal frame, with the scanlines on every line.

Black Interlaced

The image is the same height as a normal frame, with the inactive scanlines filled with black.

Line Doubled

The image is the same height as a normal frame, with the inactive scanlines filled with their active neighbor.

Odd Dominant

Odd-numbered scanline fields come before even-numbered scanline fields.

Even Dominant

Even-numbered scanline fields come before odd-numbered scanline fields.

Odd Frames Only

Only odd-numbered scanline fields are produced.

Even Frames Only

Only even-numbered scanline fields are produced.


This tab contains parameters which deal with the timing and frame range of the generated sequence.

Override Global Range

If off, the global animation range is used as the frame range. If on, the frame range of the sequence can be specified in the following parameters.

Still Image

A still image is time-invariant. It exists at every frame. If off, the Start Frame and Length are used to determine the frame range.

Start Frame

The starting frame of the sequence.


The length of the sequence (number of frames in the sequence).

Frame Rate

If on, the frame rate of the sequence can be overridden.

Pre Extend

For sequences with a frame range, this determines how to show frames before the start frame.

Black Frames

Display black.


Cycle the sequence, always playing it forward.


Cycle the sequence, reversing the direction every cycle.


Hold the first frame indefinitely.

Hold N Frames

Hold the first frame for a certain number of frames; before that, show black frames.

Pre Hold

The number of frames to hold the first frame for, if 'Hold N Frames' is selected.

Post Extend

For sequences with a frame range, this determines how to show frames after the last frame.

Black Frames

Display black.


Cycle the sequence, always playing it forward.


Cycle the sequence, reversing the direction every cycle.


Hold the last frame indefinitely.

Hold N Frames

Hold the last frame for a certain number of frames; after that, show black frames.

Post Hold

The number of frames to hold the last frame for, if 'Hold N Frames' is selected.



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

Compositing nodes

  • Add

    Adds two images together.

  • Anaglyph

    Creates an anaglyph from a pair of input images.

  • Atop

    Composites the first input (Foreground) over the second (background), but only where the background alpha exists.

  • Average

    Averages the foreground image and the background image.

  • Blend

    Blends frames from two sequences together using a simple linear blend.

  • Blur

    Blurs an image.

  • Border

    Adds a border to the image.

  • Bright

    Applies a brightness factor and bright shift to the first input.

  • Bump

    Builds a bump map from a plane.

  • COP generators

  • Channel Copy

    Copy channels from any of inputs into the output image.

  • Chromakey

    Mask or key an image based on its color.

  • Color

    Creates a constant color image.

  • Color Correct

    Applies a variety of color corrections to the image

  • Color Curve

    Adjusts the R,G,B and/or A channels based on a user-defined curve.

  • Color Map

    Maps a range of color to a new range.

  • Color Replace

    Replace a color region in an image with another region.

  • Color Wheel

    Generates a simple HSV color wheel.

  • Composite

    Does a composite (over, under, inside, add, etc) between two images.

  • Contrast

    Increases or decreases the contrast of an image.

  • Convert

    Changes the data format of a plane.

  • Convolve

    Performs a generic convolve on the source image.

  • Corner Pin

    Fits an image into an arbitrary quadrilateral.

  • Corner Ramp

    Generates a four corner ramp.

  • Crop

    Crops an image and changes its resolution.

  • Cryptomatte

    Extracts matte from Cryptomatte image.

  • DSM Flatten

    Flattens a Deep Shadow/Camera Map into a flat 2D raster.

  • Defocus

    Defocuses an image similar to a real camera defocus.

  • Deform

    Deforms an image by moving the underlying UV coordinates.

  • Degrain

    Removes film grain from an image.

  • Deinterlace

    De-interlaces a frame of video by either averaging scanlines or copying a scanline.

  • Delete

    Removes planes or components from an input sequence.

  • Denoise

    Removes white noise from an image.

  • Denoise AI

    Uses machine-learning algorithms to denoise images with high quality and speed.

  • Depth Darken

    Darkens depth boundaries in an image.

  • Depth of Field

    Creates a depth-of-field mask, which describes how out of focus parts of the image are.

  • Diff

    Computes the difference between the foreground image and the background image.

  • Dilate/Erode

    Expands and shrinks mattes.

  • Drop Shadow

    Creates a blurred shadow offset of an image.

  • Edge Blur

    Blurs the edges of an image.

  • Edge Detect

    Detects edges in the input image.

  • Emboss

    Adds a lighting effect to the image by using a bump map.

  • Environment

    Applies an environment map to an image.

  • Equalize

    Equalizes colors by stretching or shifting the image histogram.

  • Error Function Table Generator

    Creates an image containing precomputed error function terms for hair albedo computation

  • Expand

    Expands and shrinks mattes.

  • Extend

    Extends the length of a sequence so that it can be animated beyond its frame range.

  • Extract

    Extracts a plane or channel from a multi-plane source.

  • Extrapolate Boundaries

    Fills empty areas of an image using the colors at the edges the non-empty areas.

  • Fetch

    Fetches a sequence of images from another COP, even in another network.

  • Field Merge

    Merges two fields into one Interlaced Frame.

  • Field Split

    Splits an interlaced frame into two fields per frame (odd and even fields).

  • Field Swap

    Swaps the two fields containing the even and odd scanlines of the frame.

  • File

    Loads image files into Houdini.

  • Flip

    Flips the image horizontally and/or vertically.

  • Fog

    Adds a variety of atmospheric effects to an image, including fog, haze and heat waves.

  • Font

    Renders anti-aliased text.

  • Front Face

    Cleans up flipped normals by making them face the camera.

  • Function

    Performs a variety of mathematical functions on the input image.

  • Gamma

    Applies gamma correction to the image.

  • Geokey

    Keys out parts of the image based on pixel position or normal direction.

  • Geometry

    Renders geometry from a SOP as a single color image.

  • Gradient

    Computes the gradient of an image.

  • Grain

    Adds grain to an image.

  • HSV

    Converts between RGB and HSV color spaces, or applies hue and saturation modifications.

  • Hue Curve

    Adjusts the saturation or luminance of the image based on hue.

  • Illegal Pixel

    Detects illegal pixels, like NAN and INF, in images.

  • Inside

    Restricts the foreground color to the area of the background’s alpha matte.

  • Interleave

    Interleaves image sequences.

  • Invert

    Applies a photographic pixel inversion to the image.

  • Labs Attribute Import

    Imports geometry attributes as imageplanes using a uv attribute

  • Labs Blackbody

    Generates a blackbody ramp, or colorizes a black and white image with a blackbody ramp

  • Labs DDS File

    Reads in DDS (DirectDraw Surface) Files

  • Labs Demosaic

    Converts a single mosaic (flipbook/subuv) image into a sequence of sub images based on the frame

  • Labs Grid Texture

    Generates a texture that can be used as a simple resolution checkerboard

  • Labs Normal Color

    Simple Helper Node to generate the default Normal Color

  • Labs Normal Combine

    A Simple Node That Overlays 2 Normal Maps together

  • Labs Normal From Grayscale

    Convert a Grayscale Image Into a Normal Map

  • Labs Normal Invert

    Invert individual channels on an image

  • Labs Normal Levels

    Adjusts black point, white point, and midrange to increase, balance, or decrease contrast on a Normal Map.

  • Labs Normal Rotate

    Rotates a Normal Map while correcting recalculating it’s internal vectors

  • Labs Normalize Normal

    Ensures the normal map is balanced in a unit vector

  • Labs Substance Archive

    Load Substance Archive (SBSAR) Files into COPs

  • Layer

    Layers a series of inputs together by compositing them one by one on the background image (input 1).

  • Levels

    Adjusts black point, white point, and midrange to increase, balance, or decrease contrast.

  • Lighting

    Adds a light to the image.

  • Limit

    Limits the pixel range at the high end, low end or both.

  • Lookup

    Applies a lookup table to the input.

  • Luma Matte

    Sets the alpha to the luminance of the color.

  • Lumakey

    Keys the image based on luminance (or similar function).

  • Mask

    Masks out an area of an image.

  • Max

    Outputs the maximum value of the foreground and background images for each pixel, which tends to lighten the image.

  • Median

    Applies a 3 x 3 or 5 x 5 median filter to the input image.

  • Merge

    Merges the planes of several inputs together.

  • Metadata

    Applies metadata to an image sequence.

  • Min

    Outputs the minimum value of the foreground and background images for each pixel, which tends to darken the image.

  • Mono

    Converts a color or vector into a scalar quantity, like luminance or length.

  • Mosaic

    Takes a sequence of images and combines them into 1 image by tiling them.

  • Multiply

    Multiplies the foreground image with the background image.

  • Noise

    Generates continuous noise patterns.

  • Null

    Does nothing.

  • Outside

    Restricts the foreground color to the area outside of the background’s alpha matte.

  • Over

    Composites the first input (Foreground) over the second (background).

  • Pixel

    Modifies an image’s pixels using expressions.

  • Premultiply

    Allows colour to be converted to or from a premultiplied form.

  • Pulldown

    Performs a pulldown (cine-expand) on the input sequence.

  • Pushup

    Performs a pushup (cine-expand) on the input sequence.

  • Quantize

    Quantizes input data into discrete steps.

  • ROP File Output

    Renders frames out to disk.

  • Radial Blur

    Does a radial or angular blur.

  • Ramp

    Generates a variety of linear and radial ramps, which are fully keyframable.

  • Reference

    Copies the sequence information from its input.

  • Rename

    Change the name a plane.

  • Render

    Renders a mantra output driver directly into a composite network.

  • Reverse

    Simply reverses the frames in the sequence.

  • Rotoshape

    Draws one or more curves or shapes.

  • SOP Import

    Imports a 2d Volume from SOPs as planes into a composite network.

  • Scale

    Changes the resolution of the image.

  • Screen

    Adds two images together, saturating at white like photographic addition.

  • Sequence

    Sequences two or more inputs end to end.

  • Shape

    Generates simple shapes, such as circles, stars and regular N-sided polygons.

  • Sharpen

    Sharpens an image by enhancing the contrast of edges.

  • Shift

    Shifts an image sequence in time.

  • Shuffle

    Shuffle frames around to do out-of-order editing.

  • Sky Environment Map

    Creates sky and ground images for use as environment maps.

  • Snip

    Either removes frames from a sequence or allows you to order them in a user-defined order.

  • Streak Blur

    Streaks an image, adding a motion blur effect.

  • Subnetwork

    Contains networks of other COPs.

  • Subtract

    Subtracts the foreground image from the background image.

  • Switch

    Passes the input of one of its connected inputs through, acting like an exclusive switch.

  • Switch Alpha

    Replaces input 1's alpha with input 2's alpha.

  • Terrain Noise

    Generate noise suitable for terrain height maps.

  • Tile

    Tiles the image sequence with multiple copies of the input image.

  • Time Filter

    Blurs a pixel through several frames.

  • Time Machine

    Uses a second input to time warp the first input on a per pixel basis.

  • Time Scale

    Stretches or compresses a sequence in time.

  • Time Warp

    Warps time by slowing or speeding it up throughout the sequence.

  • Transform

    Translates, rotates and/or scales the input image without changing the image resolution.

  • Trim

    Trims an input sequence in time by adjusting the beginning or the end of the sequence.

  • UV Map

    Creates a UV map.

  • Under

    Composites the first input (Foreground) under the second (background).

  • Unpin

    Extracts an arbitrary quadrilateral area out of the input image.

  • VEX Filter

    Runs a VEX script on its input planes.

  • VEX Generator

    Runs a VEX script on the planes it generates.

  • VOP COP2 Filter

    Contains a VOP network that filters input image data.

  • VOP COP2 Generator

    Contains a VOP network that generates image data.

  • Vector

    Performs vector operations on the input.

  • Velocity Blur

    Blurs an image by using pixel velocity to produce a motion blur effect.

  • Window

    Cuts a small window out of a larger image.

  • Wipe

    Does a wipe between two input sequences.

  • Xor

    Makes two elements mutually exclusive; if their alpha mattes overlap, the overlap is removed.

  • Z Comp

    Does a Z composite of two images.