Simple camera calibration for light measurements
The availability and decreasing prices of digital photographic cameras using megapixel sensors could point to its use as high quality light measuring devices if simple and effective calibration procedures could be put to work. This paper proposes such a system, using a common digital camera combined with low cost reference color charts. The procedure to obtain the response function of the camera, the production of the color chart and its calibration is presented. In this way, it is possible to obtain light measurements otherwise only possible with sophisticated and expensive equipments.
Linear versus Non-Linear Digital Image Processing Methods
A process for preparing a silane of the formula I R1nSiR2m(I)where R1 is -O-Y, n is an integer from 1 to 3, R2 is m is an integer from 1 to 3 and n+m=4, and Y and Z are each, independently of one another, unsubstituted or mono- or polyhalo-substituted C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl and -(CH2)p-A, where p is an integer from 0 to 6 and A, which is unsubstituted or substituted by one or more C1-C6-alkyls, is a 3- to 20-membered hydrocarbon ring entails reacting a halosilicon compound of the formula II SiX4(II)where X is fluorine, chlorine, bromine and iodine, with compounds of the formula III and IV, or with an anhydride of the formula V and the compound of the formula IV MR2 (III) HR1 (IV) (V) where R1 and R2, and Z have the above meanings, M is a metal of main group one and two.
First diamino Daphniphyllum alkaloid, daphnipaxinin, with an unprecedented heterohexacyclic skeleton from Daphniphyllum paxianum.
[structure: see text] The first diamino Daphniphyllum alkaloid, daphnipaxinin (1), with an unprecedented hexacyclic fused skeleton, along with a known alkaloid, daphnicyclidin A (2), was isolated from the stem of Daphniphyllum paxianum Rosenth. The structure and absolute stereochemistry of 1 were established by spectral methods, especially two-dimensional NMR techniques and CD analysis.