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Old network
As of Houdini 20.5, use Copernicus nodes instead of Compositing nodes. Though both networks still exist, the Compositing network is now designated as COP Network - Old. The Compositing network and its nodes will be deprecated and then removed in a future Houdini release.
See also how to distort or convolve an image .
Glow ¶
To create a glow effect, blur the bright parts of the image.
-
Use the
Lumakey operator to extract the
bright parts of the image as a matte . -
Use a
Bright operator to increase the
brightness of the extracted matte (because the blurring step
will dim it back down). -
Use a blur node to blur the matte. The blur softens the highlights, and basically determines the amount of glow.
-
Combine the blurred matte back over the original image.
Drop shadow ¶
-
Use the
Channel Copy operator to set
the Color channel to black (or whatever color you want for the
shadow). -
Use a blur node to blur the shadow.
-
Use the
Transform operator to offset the
shadow. -
Combine the original image over the shadow.
Blurs ¶
Emboss ¶
The 
Emboss operator can fake lighting by using
luminance to extract bumps, and apply specular highlights.
If you already have a bump map, connect it to the second input of Emboss to override the automatic bump detection.
Tip
For more advanced embossing, use the 
Lighting
operator with bump mapped lighting. The
Lighting COP can add atmospheric effects as well.
Fake caustics ¶
Caustics are made up of several layers of luminance noise.
-
The base layer is a gradual modulation of brightness. This is best accomplished with alligator noise, which produces the cell-like quality of underwater caustics.
-
The specular layer is made up of sharp spikes of focused light. This can be done by edge detecting the noise to extract prominent lines, and then pulling out the brightest parts. Adjust the gamma to further pull specks out of the lines, and then blur slightly to avoid pixelation.
-
Multiply the image by the base layer, and use over or screen to composite the specular highlights in.
Fake table-top reflection ¶
-
Create the reflection with the
Pin operator.
Move the corners so they form an upside-down trapezoid, with
the bottom along the axis of reflection. -
To blur the reflection, use the
Ramp operator
to create a vertical ramp fill with black at the axis of
reflection, increasing to white away from the axis. Connect
this to the 
mask input of a blur
node (with per-pixel on). This blurs little at the
closest point of reflection (black in the mask) and more
further away (white in the mask). Adjust the blur amount. -
Use an
HSV operator to reduce the saturation
of the reflection. Use a Bright operator to
dim the reflection to make it more subtle. You can also use a
Gamma operator to wash out the reflection. -
Combine the reflection, the original image, and any background plates.
Borders ¶
Use the 
Border operator to a solid color border
around the image, either by increasing the resolution to accommodate
the border, or by overwriting some of the edge information.