IR2s: interactive real photo to Sumi-e

We propose an interactive sketch-based system for rendering oriental brush strokes on complex shapes. We introduce a contour-driven approach; the user inputs contours to represent complex shapes, the system estimates automatically the optimal trajectory of the brush, and then renders them into oriental ink paintings. Unlike previous work where the brush trajectory is explicitly provided as input, we automatically estimate this trajectory from the outline of the shapes to paint using a three-stages algorithm; first complex shapes are decomposed into elementary shapes that can be rendered with a single brush stroke. Second, we formulate the optimal brush trajectory estimation as the minimization of an energy function that measures the quality of the trajectory constrained by the variation along a stroke of the painting process parameters, such as the footprint position, size, orientation, and angular velocity. Finally, the estimated trajectories are rendered into brush strokes by mapping footprint textures scanned from real images. We combine the proposed framework with an interactive segmentation in order to convert real images into Oriental ink paintings. Experiments on complex shapes show that the proposed contour-based approach produces a large variety of strokes compared to trajectory-based approaches. It is particularly suitable for converting real images into Oriental ink paintings with minimum interaction.