Houdini 18.5 Nodes Compositing nodes

File compositing node

Loads image files into Houdini.

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This COP loads image files into Houdini. Files without an animated time or frame in the filepath (i.e. default.pic, butterfly1.pic) are interpreted as single images. Otherwise, the last number in the filename (ignoring the extension) is considered to be the frame number of the image.

For numbered files, the frame range is automatically computed by searching the directory where the files found. Missing or bad frames will be replaced with black or neighboring frames, depending on the 'Missing Frames' parameter. Missing frames at the beginning or end of the sequence cannot be automatically detected, though bad frames can be replaced.

Using Proxy Images

Lower resolution images can be used in place of full-resolution images to speed up loading or to conserve space. Proxy filenames are entered in the Proxy tab. The images files themselves should be an integer reduction of the image (1/2, 1/3, 1/4, etc). The main files do not need to exist in order to use proxy files (the largest proxy files will be used).

More than one proxy file can be entered. Houdini will use the closest proxy image resolution not smaller than the current cook resolution (so if you were cooking at 1/3, and there were proxy images for 1/2 and 1/4 resolution, the 1/2 resolution images would be loaded and scaled down, rather than up-scaling the 1/3 resolution images).


Currently, the proxy images should be the same image format as the main images. This may change in the future.




The path of the file(s) to load. The file is searched for using the HOUDINI_TEXTURE_PATH. Multiple files can be specified with $F, $I or a more complicated expression for frame numbers.

File Node Naming

The File Node renames itself to match the current file settings. This parameter controls how the new name is built. User Defined or File Operator will disable this behavior. Changing the name manually will automatically switch this parameter to User Defined.

Detect Subframes

The character "." is treated as a decimal, and sequences of images with fractional frame numbers are loaded. Each fractional frame is placed at the next available integer frame in the sequence (1,2,3…), rather than at subframes (1, 1.25, 1.5…).

File Size

Specifies the size of the file to load, either by at the natural resolution or a custom size.

Image Filter

When the file size is overridden, this specifies the image filter to use when scaling.

Pixel Aspect Ratio

Specifies the pixel aspect ratio of the image.

Flip Image

Flips the image vertically if on.

File Raster Depth

Selects how the raster depth is determined.

Natural Depth

The image file’s depth is used.

Project Depth

The depth specified in the Composite Project settings is used, overriding the file’s natural depth.

Specific Depth

The following Depth parameter selects the raster depth, overriding the file’s natural depth.

Linearize Non-linear Images

When enabled, planes with non-linear colorspaces will be converted to linear colorspace. If the colorspace is unknown, only 8b images will be assumed to be sRGB. 8b non-linear planes will always be upconverted to at least 16b float, unless the File Raster Depth explicity sets a different format.

Image Color Space

When Linearize is enabled, the image color space is determined by looking at the image file itself. In some cases, the file may contain an image in a colorspace that is different that the one the format specifies (ie, an sRGB image in an OpenEXR file, which the format dictates should be linear). This parameter allows you to explicitly state the color space of the loaded image, which may affect if the image is linearized (sRGB) or not (Linear). This parameter is not used if Linearize Non-linear Images is off.

Autodetect from File

Use the image format or image file to determine the colorspace.


Assume the image is in linear space, ignoring the file or format’s colorspace. The image will not be linearized.


Assume the image is in sRGB space, ignoring the file or format’s colorspace. The image will be run through a inverse sRGB transform.


If the File Raster Depth parameter is set to Specific, this parameter sets the raster depth used for the files.

Override Frame Range

If off, the frame range is automatically determined by the lowest and highest frame numbers found in the file pattern. Otherwise the File Range Start, File Range Length, and Shift to Start at Frame parameters set the range.

Detect Frame Range

If Override Frame Range is on, you can do a one-time frame range detect of the sequence by pressing this button. It will put the range values into the following parameters.

Still Image

When checked, only the first image in the file range will be read and a still image will be created instead of a sequence.

Shift to Start at Frame

Specifies the frame where the sequence should start. If this number is different from the file range start, the sequence will be shifted appropriately.

File Range Start

Specifies the number of the first file where the sequence should start. For example, if the file name is file$F.tiff and the file range start is 15, the first file in the sequence will be file15.tiff. By default, this number is determined from the first file found matching the file name pattern, but it can be changed to create a sequence of a subset of the files.

File Range Length

Specifies the length of the sequence. By default, this number is the number of files matching the pattern. It can be changed to create a sequence of a subset of the files.

Missing Frames

If a frame is missing in the sequence, this parameter specifies how to handle it.

Missing Frames

For bad or missing frames, the File COP can either use a black frame or a neighboring frame.

Use Closest Frame

Searches forward and backward in the frames to find a substitution. The closest frame is used; in the event of a tie, the previous frame is taken.

Use Previous Frame

Searches backward from the missing frame to find a replacement.

Use Next Frame

Searches forward from the missing frame to find a replacement.

Use Black Frame

Bad and missing frames are replaced with a black frame.

Report Error

The File node errors when a bad or missing frame is found.


Enable Proxy Files

Enables the use of proxies, which are smaller versions of the full sized images. A proxy sequence should be identical to the original sequence, except for the resolution. When cooking the file COP at other resolutions than the proxy resolutions, the closest larger proxy sequence is used.

1/2, 1/4, 1/8 Res Proxy

Specifies the proxy sequence to use for 1/2, 1/4 and 1/8 of the full resolution.

Custom Proxy

Allows you to specify other proxy resolutions and their proxy sequences.


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 (bottom 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.

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

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.


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

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.

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.

  • Compositing nodes

    Composite nodes create, filter, and manipulate image data.

  • 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 noise from the input image.

  • Denoise

    Removes white noise from an image.

  • 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.

  • 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.

  • 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.