Rendering Tip - Adjustments and Filters


Post processing is a method by which images are modified to improve or embellish them. Many SketchUp users rely on image-editing software such as Photoshop™ or Gimp™, however there are rendering extensions for SketchUp that include many of the same editing features. The above images are of a SketchUp model from the 3D Warehouse. For the purposes of this rendering tip, this model was rendered with IRender nXt and then modified with post processing methods included with it.

The post processing functions included with IRender nXt can be used:

  1. While the rendering is processing
  2. Immediately after the rendering is finished
  3. Later when you save the finished rendering as a native ".nxtImage" file.

I saved the rendering as a native .nxtImage, PoolHouse.nxtImage.

If you have the IRender nXt extension for SketchUp installed, open any .nxtImage for edits, by CLICKING AF2.png on the IRender nXt toolbar, then browse to find the .nXtImage:


Post Processing Options

The .nXt Image Editor includes 3 post processing interfaces:

Adjustments: Brightness, Contrast, Burn, Saturation
Filters: Sharpen, Soften, Smooth, Gamma, Gaussian, Emboss, Edge
Light Balancer:
Adjust the balance between the Sun and Sky, and artificial lighting
Haze, Blur, Glare

Adjustments and Filters

The Adjustments and Filters interface can be used while the rendering is processing or after the rendering is finished. Using the methods included in this interface while the rendering is processing is advantageous because as the rendering proceeds any applied adjustments or filters will be retained.

Similarly, the following adjustments can be applied to the rendering to improve output to a computer display and/or hard copy. Adjustments used in combination will ensure that your presentation rendering exceeds your expectations.


Brightness: Use this adjustment to lighten or darken the rendered image.

Rendering engines calculate the overall (ambient) brightness of the image while rendering, however it's also possible to brighten or darken the rendering to match your expectation for the finished image.

10% Darker
10% Brighter

Contrast: Adjust the relative difference between light and dark areas of the rendering.

Burn: Adjust white balance in the rendered image. Note: Burn can be helpful as a way to improve the rendering of white surfaces.

Saturation: Adjust color intensity in the rendering.

The poolhouse rendering below was adjusted with the following values:

  1. Brightness: 45
  2. Contrast: 60
  3. Burn: 80
  4. Saturation: 80
Original Rendering
Adjusted Rendering

The same rendering with saturation set to 0.



  1. Sharpen - Emphasizes (highlights) edges
  2. Smooth - Reduces edge intensity, flattening the image
  3. Gaussian 3x3 - Reduces image noise/pixelation and detail using a 3x3 pixel grid across the image
  4. Emboss - Produces a 3D (monochromatic) shadowed image
  5. Soften - Reduces image noise/pixelation
  6. Gamma - Image luminance (brightness) correction
  7. Gaussian 5x5 - Reduces noise and detail using a 5x5 pixel grid across the image
  8. Edge - Reduce the rendered image to edge lines

Emboss and Edge filters in particular can produce interesting rendering options.


The following image combines the Edge filter, Saturation = 0, Burn = 70, Contrast = 100.