A Multi-Image Shape-from-Shading Framework for Near-Lighting Perspective Endoscopes
International Journal of Computer Vision
Estimating vignetting function from a single image for image authentication
Proceedings of the 12th ACM workshop on Multimedia and security
High dynamic range global mosaic
ACCV'06 Proceedings of the 7th Asian conference on Computer Vision - Volume Part I
Modeling and synthesis of aperture effects in cameras
Computational Aesthetics'08 Proceedings of the Fourth Eurographics conference on Computational Aesthetics in Graphics, Visualization and Imaging
How bright is the moon? recovering and using absolute luminance values from internet images
CCIW'13 Proceedings of the 4th international conference on Computational Color Imaging
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Cameras may have non-ideal radiometric aspects, including spatial non-uniformity, e.g., due to vignetting; nonlinear radiometric response of the sensor; and temporal variations due to automatic gain control (AGC). Often, these characteristics exist simultaneously, and are typically unknown. They thus hinder consistent photometric-measurements. In particular, they create annoying seams in image mosaics. Prior studies approached part of these problems while excluding others. We handle all these problems a unified framework. We suggest an approach for simultaneously estimating the radiometric response, the spatial non-uniformity and the temporally varying gain. The approach does not rely on dedicated processes that intentionally vary exposure settings. Rather, it is based on an ordinary frame sequence acquired during camera motion. The estimated non-ideal characteristics are then compensated for. We state fundamental ambiguities associated with this recovery problem, while exposing a novel image invariance. The method is demonstrated in several experiments, where different frames are brought into mutual radiometric consistency. The accuracy achieved is sufficient for seamless mosaicing, with no need to resort to dedicated seam-feathering methods.