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Transformation-aware perceptual image metric

Kellnhofer, P; Ritschel, T; Myskowsik, K; Seidel, H-P; (2016) Transformation-aware perceptual image metric. Journal of Electronic Imaging , 25 (5) , Article 053014. 10.1117/1.JEI.25.5.053014. Green open access

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Abstract

Predicting human visual perception has several applications such as compression, rendering, editing, and retargeting. Current approaches, however, ignore the fact that the human visual system compensates for geometric transformations, e.g., we see that an image and a rotated copy are identical. Instead, they will report a large, false-positive difference. At the same time, if the transformations become too strong or too spatially incoherent, comparing two images gets increasingly difficult. Between these two extrema, we propose a system to quantify the effect of transformations, not only on the perception of image differences but also on saliency and motion parallax. To this end, we first fit local homographies to a given optical flow field, and then convert this field into a field of elementary transformations, such as translation, rotation, scaling, and perspective. We conduct a perceptual experiment quantifying the increase of difficulty when compensating for elementary transformations. Transformation entropy is proposed as a measure of complexity in a flow field. This representation is then used for applications, such as comparison of nonaligned images, where transformations cause threshold elevation, detection of salient transformations, and a model of perceived motion parallax. Applications of our approach are a perceptual level-of-detail for real-time rendering and viewpoint selection based on perceived motion parallax.

Type: Article
Title: Transformation-aware perceptual image metric
Open access status: An open access version is available from UCL Discovery
DOI: 10.1117/1.JEI.25.5.053014
Publisher version: http://dx.doi.org/10.1117/1.JEI.25.5.053014
Language: English
Additional information: Copyright © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License (https://creativecommons.org/licenses/by/3.0/). Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Keywords: image metric; motion; optical flow; homography; saliency; motion parallax
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
URI: https://discovery.ucl.ac.uk/id/eprint/1509349
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