Bilateral Blur effect

The Bilateral Blur effect selectively blurs an image so that edges and other details are preserved. Areas with high contrast—where pixel values differ by a large amount—are blurred less than areas of low contrast.

The primary difference between the Bilateral Blur effect and the Smart Blur effect is that edges and details are still blurred a small amount by the Bilateral Blur effect. The result is a softer, dreamier look than that achieved by the Smart Blur effect with equivalent settings.

The result of the Bilateral Blur effect is very similar to the result of the Surface Blur filter in Adobe Photoshop.

Eran Stern provides a demonstration of the Bilateral Blur effect on the Motionworks website.

This effect works with 8-bpc, 16-bpc, and 32-bpc color.

The Bilateral Blur effect preserves the details in the logo and face.

Threshold
The radius of the blur is automatically decreased in areas where an edge or other prominent detail feature exists. The Threshold value determines how the Bilateral Blur effect decides what areas contain features to be preserved and what areas should be blurred by the full amount. A lower Threshold value causes more fine details to be preserved. A higher Threshold value causes a more simplistic result, with fewer details preserved.

Radius
A larger radius for a blur means that more pixels are averaged together to determine each pixel value, so increasing the Radius value increases the blurriness.

Colorize
When Colorize is not selected, the Bilateral Blur effect operates on one value for each pixel: its luminance value, which is a weighted average of its R, G, and B color channel values. The result is a monochromatic image.

When Colorize is selected, the Bilateral Blur effect operates on each color channel individually. The result is a color image.