Stylized Non-Photorealistic Rendering using Anisotropic Diffusion

Pavlos Mavridis
July 2012
EWA
Figure 1. From left to right: Original frame buffer, stylized frame buffer with color, stylized frame buffer in black and white. Original images from the Bioshock Infinite video game.

Overview

I have first learned about anisotropic diffusion algorithms from David Tschumperlé's work on the subject and the excellent GMIC software. Usually these algorithms are used for image de-noising and restoration, but it turns out that if you "abuse" them, they are very good at performing stylized non-photorealistic rendering as a post-processing operation. These filters blur the input image while preserving the details that are important for the interpretation of the original content, such as the edges of the objects and sharp details in the textures. My experiments indicate that the new technique is temporally stable and can be applied on movie sequences or the final frame buffer of video games, giving them a unique artistic style that resembles a hand-drawn comic, as demonstrated in Figure 1.

Compared to other methods, especially those used in real-time applications, this post processing technique operates only on the color channel of the frame buffer and does not require any additional inputs, such as depth or normal, therefore it can operate on any image, regardless of the method it was used to create it, making the integration with existing rendering systems trivial.

Note: I will write a more detailed description of the method in the future.

Some First Results

Choose an image from the top and hover your mouse over the labels at the bottom to compare the original frame buffer with the color or b&w illustration style.

Color Illustration
B&W Illustration

Color Illustration
B&W Illustration

Color Illustration
B&W Illustration

Color Illustration
B&W Illustration

Acknowledgements

All images from the Bioshock Infinite video game are courtesy of Irrational Games.