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.
Error diffusion using the web-safe colors: how good is it across platforms?
Accurate color rendering across displays is complicated on the World Wide Web by the color-handling properties of individual web browsers. However, the major browsers have all adopted a minimal color palette of 216 RGB triples, called the `browser-safe' colors, suitable for use with web page backgrounds and text, logos, cartoons, and line drawings. For naturalistic or photographic images, however, simple quantization to 216 colors can produce images with altered hues or color banding. We show that dithering with the browser-safe colors is a good strategy for such images, especially at spatial resolutions above 150 dpi. However, even if the RGB image is transmitted and received unaltered, the system gamma will affect appearance. Ambient lighting contributes to the rendered image's appearance, but does not mask the effects of differences in monitor gammas. The need for an image-rendering convention traceable to the CIE is underscored by these results.