Browsing by Author "Andersson, Pontus"

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    FLIP: A Difference Evaluator for Alternating Images
    (ACM, 2020) Andersson, Pontus; Nilsson, Jim; Akenine-Möller, Tomas; Oskarsson, Magnus; Åström, Kalle; Fairchild, Mark D.; Yuksel, Cem and Membarth, Richard and Zordan, Victor
    Image quality measures are becoming increasingly important in the field of computer graphics. For example, there is currently a major focus on generating photorealistic images in real time by combining path tracing with denoising, for which such quality assessment is integral. We present FLIP, which is a difference evaluator with a particular focus on the differences between rendered images and corresponding ground truths. Our algorithm produces a map that approximates the difference perceived by humans when alternating between two images. FLIP is a combination of modified existing building blocks, and the net result is surprisingly powerful. We have compared our work against a wide range of existing image difference algorithms and we have visually inspected over a thousand image pairs that were either retrieved from image databases or generated in-house. We also present results of a user study which indicate that our method performs substantially better, on average, than the other algorithms. To facilitate the use of FLIP, we provide source code in C++, MATLAB, NumPy/SciPy, and PyTorch.
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    Temporally Dense Ray Tracing
    (The Eurographics Association, 2019) Andersson, Pontus; Nilsson, Jim; Salvi, Marco; Spjut, Josef; Akenine-Möller, Tomas; Steinberger, Markus and Foley, Tim
    We present a technique for real-time ray tracing with the goal of reaching 240 frames per second or more. The core idea is to trade spatial resolution for faster temporal updates in such a way that the display and human visual system aid in integrating high-quality images. We use a combination of frameless and interleaved rendering concepts together with ideas from temporal antialiasing algorithms and novel building blocks-the major one being adaptive selection of pixel orderings within tiles, which reduces spatiotemporal aliasing significantly. The image quality is verified with a user study. Our work can be used for esports or any kind of rendering where higher frame rates are needed.
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    Visualizing Errors in Rendered High Dynamic Range Images
    (The Eurographics Association, 2021) Andersson, Pontus; Nilsson, Jim; Shirley, Peter; Akenine-Möller, Tomas; Theisel, Holger and Wimmer, Michael
    A new error metric targeting rendered high dynamic range images is presented. Our method computes a composite visualization over a number of low dynamic range error maps of exposure compensated and tone mapped image pairs with automatically computed, or manually provided, parameters. We argue that our new error maps predict errors substantially better than metrics previously used in rendering. Source code is released with the hope that our work can be a useful tool for future research.