Raw image format

A camera raw image file contains minimally processed data from the image sensor of either a digital camera, image scanner, or motion picture film scanner. Raw files are named so because they are not yet processed and therefore are not ready to be printed or edited with a bitmap graphics editor. Normally, the image is processed by a raw converter in a wide-gamut internal colorspace where precise adjustments can be made before conversion to a "positive" file format such as TIFF or JPEG for storage, printing, or further manipulation, which often encodes the image in a device-dependent colorspace. There are dozens, if not hundreds, of raw formats in use by different models of digital equipment (like cameras or film scanners).

Rationale

Raw image files are sometimes called digital negatives, as they fulfill the same role as negatives in film photography: that is, the negative is not directly usable as an image, but has all of the information needed to create an image. Likewise, the process of converting a raw image file into a viewable format is sometimes called developing a raw image, by analogy with the film development process used to convert photographic film into viewable prints. The selection of the final choice of image rendering is part of the process of white balancing and color grading.

SRF-39

The SRF-39 is a portable AM/FM radio made by Sony. It uses a single AA battery, as its analog electronics draw very little current. It was one of the first radios to use the CXA1129 30-pin integrated circuit, which later was responsible for the SRF-59's sensitive and selective performance.

A variant of the SRF-39, the SRF-39FP, has a transparent case, designed to thwart contraband concealment. The radio often appears on the commissary lists of U.S. federal prisons, hence the "FP" suffix. Both are popular in the DXing community partly for their generous recessed area for the tuning thumbwheel, 0-10 log strip, and guard chain.

References

Strontium fluoride

Strontium fluoride, SrF₂, also called strontium difluoride and strontium(II) fluoride, is a fluoride of strontium. It is a stable brittle white crystalline solid with melting point of 1477 °C and boiling point 2460 °C.

Preparation

Strontium fluoride is prepared by reaction of strontium chloride with fluorine gas, or by action of hydrofluoric acid on strontium carbonate.

Structure

The solid adopts the fluorite structure. In the vapour phase the SrF₂ molecule is non-linear with an F-Sr-F angle of approximately 120°. This is an exception to VSEPR theory which would predict a linear structure. Ab initio calculations have been cited to propose that contributions from d orbitals in the shell below the valence shell are responsible. Another proposal is that polarization of the electron core of the strontium atom creates an approximately tetrahedral distribution of charge that interacts with the Sr-F bonds.

Properties

It is almost insoluble in water (its K_sp value is approximately 2.0x10⁻¹⁰ at 25 degrees Celsius.
It irritates eyes and skin, and is harmful when inhaled or ingested.
Similar to CaF₂ and BaF₂, SrF₂ displays superionic conductivity at elevated temperatures.
Strontium fluoride is transparent to light in the wavelengths from vacuum ultraviolet (150 nm) to infrared (11 µm). Its optical properties are intermediate to calcium fluoride and barium fluoride.