An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A method of improving → spatial resolution of images. → pupil masking; → unsharp masking.
2) Computers: The process of specifying a number of values that allow extracting desired information from a set of characters or bits while suppressing the undesired information.

Verbal noun of → mask.

A method for reaching the → diffraction-limited  → angular resolution of a monolithic telescope by using an → interferometric technique. A mask with several small openings is placed in the telescope pupil plane or in a conjugated plane so as to only pass light from selected regions, thus transforming the telescope into an array of small subapertures without redundancy. When the light from each of these separate subapertures is combined, → interference fringes are formed which encode information on the spatial structure of the source (Haniff et al. 1987, Nature 328, 694). Coupled with a novel technique which filters the → atmospheric turbulence through fibers, pupil masking allows reaching a high dynamic range (Perrin et al. 2006, MNRAS 373, 747), which is necessary for detecting very faint objects, such as → exoplanets, adjacent to bright stars.

→ pupil; → masking.

1) The external protective membrane or covering of an animal's body, or that surrounding the flesh of a fruit or vegetable.
2) The outer protective covering of a structure. → skin effect.

M.E., from O.N. skinn "animal hide;" cf. O.H.G. scinten, Ger. schinden "to flay, skin;" Ger. dialect schind "skin of a fruit," Flemish schinde "bark;" from PIE *sken- "to cut off."

Pust "skin;" Mid.Pers. pôst "skin;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Av. pastô-, in pastô.fraθanhəm "of the breadth of the skin;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth."

The tendency of an → alternating current to concentrate in the outer layer of a conductor, caused by the → self-induction of the → conductor and resulting in increased → resistance.

→ skin; → effect.

A process for amplifying fine details in a registered image. Generally speaking, the process consists of creating a mask which contains larger scale features of the image and then subtracting the mask from the initial image.

→ un-; → sharp; → masking.