Color smudge operations from digital painting software enable users to create natural shading effects in high-fidelity paintings by interactively mixing colors. To precisely control results in traditional painting software, users tend to organize flat-filled color regions in multiple layers and smudge them to generate different color gradients. However, the requirement to carefully deal with regions makes the smudging process time-consuming and laborious, especially for non-professional users. This motivates us to investigate how to infer user-desired smudging effects when users smudge over regions in a single layer. To investigate improving color smudge performance, we first conduct a formative study. Following the findings of this study, we design SmartSmudge, a novel smudge tool that offers users dynamical smudge brushes and real-time region selection for easily generating natural and efficient shading effects. We demonstrate the efficiency and effectiveness of the proposed tool via a user study and quantitative analysis

翻译：数字绘画软件中的颜色涂抹操作允许用户通过交互式混合颜色，在高质量绘画中创建自然的阴影效果。为了精准控制传统绘画软件中的效果，用户倾向于将平涂颜色区域分层组织，并通过涂抹生成不同的颜色渐变。然而，仔细处理区域的要求使得涂抹过程耗时费力，尤其对非专业用户而言。这促使我们探究当用户在单层区域上涂抹时，如何推断用户期望的涂抹效果。为了提升颜色涂抹性能，我们首先进行了一项形成性研究。基于该研究的发现，我们设计了SmartSmudge——一种新型涂抹工具，能够为用户提供动态涂抹笔刷和实时区域选择功能，从而轻松生成自然且高效的阴影效果。我们通过用户研究和定量分析证明了所提工具的效率和有效性。