Prof. Dr. Jürgen Döllner


Two contributions accepted for SIGGRAPH Asia MGIA 2016

Two contributions have been accepted to the SIGGRAPH Asia 2016 Symposium on Mobile Graphics and Interactive Applications (MGIA): (1) the technical paper "Interactive Image Filtering with Multiple Levels-of-Control on Mobile Devices" by Amir Semmo, Tobias Dürschmid, Matthias Trapp, Mandy Klingbeil, Jürgen Döllner and Sebastian Pasewaldt, and (2) the demo "BeCasso: Non-photorealistic Image Processing and Editing on Mobile Devices" by Sebastian Pasewaldt, Amir Semmo, Jürgen Döllner and Frank Schlegel. The symposium will be held in conjunction with the 9th ACM SIGGRAPH conference and exhibition on computer graphics and interactive techniques in Asia, which will be held in Macao from the 5th to 8th of December. Members of the research group will present the contributions in a talk and live demo at SIGGRAPH Asia in cooperation with Digital Masterpieces GmbH, a spin-off of the Computer Graphics Systems Group at the Hasso Plattner Institute.


Abstract (Technical Paper)

With the continuous development of mobile graphics hardware, interactive high-quality image stylization based on nonlinear filtering is becoming feasible and increasingly used in casual creativity apps. However, these apps often only serve high-level controls to parameterize image filters and generally lack support for low-level (artistic) control, thus automating art creation rather than assisting it. This work presents a GPU-based framework that enables to parameterize image filters at three levels of control: (1) presets followed by (2) global parameter adjustments can be interactively refined by (3) complementary on-screen painting that operates within the filters' parameter spaces for local adjustments. The framework provides a modular XML-based effect scheme to effectively build complex image processing chains-using these interactive filters as building blocks-that can be efficiently processed on mobile devices. Thereby, global and local parameterizations are directed with higher-level algorithmic support to ease the interactive editing process, which is demonstrated by state-of-the-art stylization effects, such as oil paint filtering and watercolor rendering.

Abstract (Demo)

BeCasso is a mobile app that enables users to transform photos into high-quality, high-resolution non-photorealistic renditions, such as oil and watercolor paintings, cartoons, and colored pencil drawings, which are inspired by real-world paintings or drawing techniques. In contrast to neuronal network and physically-based approaches, the app employs state-of-the-art nonlinear image filtering. For example, oil paint and cartoon effects are based on smoothed structure information to interactively synthesize renderings with soft color transitions. BeCasso empowers users to easily create aesthetic renderings by implementing a two-fold strategy: First, it provides parameter presets that may serve as a starting point for a custom stylization based on global parameter adjustments. Thereby, users can obtain initial renditions that may be fine-tuned afterwards. Second, it enables local style adjustments: using on-screen painting metaphors, users are able to locally adjust different stylization features, e.g., to vary the level of abstraction, pen, brush and stroke direction or the contour lines. In this way, the app provides tools for both higher-level interaction and low-level control to serve the different needs of non-experts and digital artists.