Browsing by Author "Li, Frederick W. B."

Now showing 1 - 4 of 4
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    Aesthetic Enhancement via Color Area and Location Awareness
    (The Eurographics Association, 2022) Yang, Bailin; Wang, Qingxu; Li, Frederick W. B.; Liang, Xiaohui; Wei, Tianxiang; Zhu, Changrui; Yang, Yin; Parakkat, Amal D.; Deng, Bailin; Noh, Seung-Tak
    Choosing a suitable color palette can typically improve image aesthetic, where a naive way is choosing harmonious colors from some pre-defined color combinations in color wheels. However, color palettes only consider the usage of color types without specifying their amount in an image. Also, it is still challenging to automatically assign individual palette colors to suitable image regions for maximizing image aesthetic quality. Motivated by these, we propose to construct a contribution-aware color palette from images with high aesthetic quality, enabling color transfer by matching the coloring and regional characteristics of an input image. We hence exploit public image datasets, extracting color composition and embedded color contribution features from aesthetic images to generate our proposed color palettes. We consider both image area ratio and image location as the color contribution features to extract. We have conducted quantitative experiments to demonstrate that our method outperforms existing methods through SSIM (Structural SIMilarity) and PSNR (Peak Signal to Noise Ratio) for objective image quality measurement and no-reference image assessment (NIMA) for image aesthetic scoring.
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    A Color-Pair Based Approach for Accurate Color Harmony Estimation
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Yang, Bailin; Wei, Tianxiang; Fang, Xianyong; Deng, Zhigang; Li, Frederick W. B.; Ling, Yun; Wang, Xun; Lee, Jehee and Theobalt, Christian and Wetzstein, Gordon
    Harmonious color combinations can stimulate positive user emotional responses. However, a widely open research question is: how can we establish a robust and accurate color harmony measure for the public and professional designers to identify the harmony level of a color theme or color set. Building upon the key discovery that color pairs play an important role in harmony estimation, in this paper we present a novel color-pair based estimation model to accurately measure the color harmony. It first takes a two-layer maximum likelihood estimation (MLE) based method to compute an initial prediction of color harmony by statistically modeling the pair-wise color preferences from existing datasets. Then, the initial scores are refined through a back-propagation neural network (BPNN) with a variety of color features extracted in different color spaces, so that an accurate harmony estimation can be obtained at the end. Our extensive experiments, including performance comparisons of harmony estimation applications, show the advantages of our method in comparison with the state of the art methods.
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    A Differential Diffusion Theory for Participating Media
    (The Eurographics Association and John Wiley & Sons Ltd., 2023) Cen, Yunchi; Li, Chen; Li, Frederick W. B.; Yang, Bailin; Liang, Xiaohui; Chaine, Raphaƫlle; Deng, Zhigang; Kim, Min H.
    We present a novel approach to differentiable rendering for participating media, addressing the challenge of computing scene parameter derivatives. While existing methods focus on derivative computation within volumetric path tracing, they fail to significantly improve computational performance due to the expensive computation of multiply-scattered light. To overcome this limitation, we propose a differential diffusion theory inspired by the classical diffusion equation. Our theory enables real-time computation of arbitrary derivatives such as optical absorption, scattering coefficients, and anisotropic parameters of phase functions. By solving derivatives through the differential form of the diffusion equation, our approach achieves remarkable speed gains compared to Monte Carlo methods. This marks the first differentiable rendering framework to compute scene parameter derivatives based on diffusion approximation. Additionally, we derive the discrete form of diffusion equation derivatives, facilitating efficient numerical solutions. Our experimental results using synthetic and realistic images demonstrate the accurate and efficient estimation of arbitrary scene parameter derivatives. Our work represents a significant advancement in differentiable rendering for participating media, offering a practical and efficient solution to compute derivatives while addressing the limitations of existing approaches.
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    Recognising Human-Object Interactions Using Attention-based LSTMs
    (The Eurographics Association, 2019) Almushyti, Muna; Li, Frederick W. B.; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.
    Recognising Human-object interactions (HOIs) in videos is a challenge task especially when a human can interact with multiple objects. This paper attempts to solve the problem of HOIs by proposing a hierarchical framework that analyzes human-object interactions from a video sequence. The framework consists of LSTMs that firstly capture both human motion and temporal object information independently, followed by fusing these information through a bilinear layer to aggregate human-object features, which are then fed to a global deep LSTM to learn high-level information of HOIs. The proposed approach applies an attention mechanism to LSTMs in order to focus on important parts of human and object temporal information.