7,411 research outputs found
Convex Optimization Based Bit Allocation for Light Field Compression under Weighting and Consistency Constraints
Compared with conventional image and video, light field images introduce the
weight channel, as well as the visual consistency of rendered view, information
that has to be taken into account when compressing the pseudo-temporal-sequence
(PTS) created from light field images. In this paper, we propose a novel frame
level bit allocation framework for PTS coding. A joint model that measures
weighted distortion and visual consistency, combined with an iterative encoding
system, yields the optimal bit allocation for each frame by solving a convex
optimization problem. Experimental results show that the proposed framework is
effective in producing desired distortion distribution based on weights, and
achieves up to 24.7% BD-rate reduction comparing to the default rate control
algorithm.Comment: published in IEEE Data Compression Conference, 201
Hankel determinants, Pad\'e approximations, and irrationality exponents
The irrationality exponent of an irrational number , which measures the
approximation rate of by rationals, is in general extremely difficult to
compute explicitly, unless we know the continued fraction expansion of .
Results obtained so far are rather fragmentary, and often treated case by case.
In this work, we shall unify all the known results on the subject by showing
that the irrationality exponents of large classes of automatic numbers and
Mahler numbers (which are transcendental) are exactly equal to . Our classes
contain the Thue--Morse--Mahler numbers, the sum of the reciprocals of the
Fermat numbers, the regular paperfolding numbers, which have been previously
considered respectively by Bugeaud, Coons, and Guo, Wu and Wen, but also new
classes such as the Stern numbers and so on. Among other ingredients, our
proofs use results on Hankel determinants obtained recently by Han.Comment: International Mathematics Research Notices 201
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