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- D R White, P Saunders, S J Bonsey, J van de Ven, H Edgar
- Applied optics
- 1998

A fully automatic, four-axis gonioreflectometer is described. It has an angular accuracy of 0.3 degrees and a range of 90 degrees in both the theta(i) and the theta(r) zenith angles. The gonioreflectometer is simpler than previous designs because of its use of rotating arms rather than moving carriages to mount the optical components. Where possible,… (More)

Given a totally real algebraic number field K, we investigate when totally positive units, U¿, are squares, u£. In particular, we prove that the rank of U¿ /Ují is bounded above by the minimum of (1) the 2-rank of the narrow class group of K and (2) the rank of Ul /U¿ as L ranges over all (finite) totally real extension fields of K. Several applications are… (More)

Vector quantisation (VQ) is a popular image-coding method but its performance is limited due to restrictions on the size of its codebook. Processing time and storage space increase exponentially with the size of the codeword. This paper proposes Symmetry-Folded Classified VQ (SFC-VQ), a novel VQ coding technique that combines symmetry folding with… (More)

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