Real-time structure aware color stippling

Abstract

In computer graphics, stippling is a widely used non-photorealistic rendering technique. As the art of representing images with dots, one of the key problems is the placement of dots. In general, they should be distributed evenly, and with some randomness at the same time. Blue noise methods provide these characteristics and are used by state-of-the-art gray-scale algorithms to distribute dots. Color stippling, however, is more challenging as each channel should have even distribution at the same time. Existing approaches cast color stippling as a multi-class blue noise sampling problem and provide high quality results at the cost of a very long processing time. In this paper, we propose a real-time structure aware method for color stippling, based on samples generated from an incremental voronoi set. Our method can handle an arbitrary input color vector for stippling and produce significantly better results than previous methods, at real-time frame rate. We evaluate the perceptual quality of our stippling with a user study and its numerical performance by measuring the MSE between the reconstructed image from the stippling and the input image. As a result, the real time performance of our method makes interactive stippling editing possible, providing the artist with an effective tool to explore quickly a wide space of color image stippling.