Software for producing trichromatic images in astronomy

We present a software package for combining three monochromatic images of an astronomical object into a trichromatic color image. We first discuss the meaning of "true" colors in astronomical images. We then describe the different steps of our method, choosing the relevant dynamic intensity range in each filter, inventorying the different colors, optimizing the color map, modifying the balance of colors, and enhancing contrasts at low intensity levels. While the first steps are automatic, the last two are interactive.Comment: 12 pages (including 2 figures) uuencoded compressed Postscript file. To appear in Experimental Astronom

Equiripple design of real and complex filter banks [Gerçtrel ve karmaşik süzgeç öbeklerinin eşdalgacikli tasarimi]

2006 IEEE 14th Signal Processing and Communications Applications -- 17 April 2006 through 19 April 2006 -- Antalya -- 69461A simple methodology is presented for mapping minimax-optimal, equiripple unconstrained filters such as those produced by the Parks-McClellan algorithm to design equiripple perfect-reconstruction filter banks. The method is applied both to the design of standard low- and high-pass filters for perfect reconstruction, and to the design of critically sampled complex filters. For the case of real filter-bank design, our method produces equiripple low- and high-pass filters optimizing standard minimax filter design criteria while meeting the constraints of perfect reconstruction. For the case of complex filter-bank design, our method generates a critically-sampled, envelop/phase representation of a resonating signal while allowing perfect reconstruction. The magnitude response of the complex filter is an equiripple approximation to an ideal positive frequency passband, and the phase response is an equiripple approximation of pure linear phase. © 2006 IEEE