Houdini 19.5 Compositing

Common image effects

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See also how to distort or convolve an image .


To create a glow effect, blur the bright parts of the image.

  1. Use the Lumakey operator to extract the bright parts of the image as a matte .

  2. Use a Bright operator to increase the brightness of the extracted matte (because the blurring step will dim it back down).

  3. Use a blur node to blur the matte. The blur softens the highlights, and basically determines the amount of glow.

  4. Combine the blurred matte back over the original image.

Drop shadow

  1. Use the Channel Copy operator to set the Color channel to black (or whatever color you want for the shadow).

  2. Use a blur node to blur the shadow.

  3. Use the Transform operator to offset the shadow.

  4. Combine the original image over the shadow.



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.


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

  1. 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.

  2. 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.

  3. 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.

  4. Combine the reflection, the original image, and any background plates.


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.




Camera effects


Guru level