The authors study the application of the phase retrieval algorithm suggested by Walker (1982) to 1-D short-exposure images obtained by infrared stellar speckle interferometry. To verify its performance, the algorithm has been tested previously with 1-D computer simulated speckle images.

The authors present the first astronomical images reconstructed from their autocorrelation functions using an improved version of the simulated annealing algorithm.

Type I post-main-sequence nebulae appear to be characterised by a range of unusual, and in certain cases extreme physical characteristics, including high velocity (and possibly high mass) outflows, and anomalous He, N, and C abundances; a feature which is almost certainly indicative of high mass nebular progenitors. The authors have acquired high

Image sharpening techniques applied to medium size telescopes (approximately 1 m) can improve their resolution by double. A new algorithm for recentering and selecting better quality images has been developed. The authors carried out a comparative study with other algorithms in terms of spatial resolution and photometric response. Conclusions are

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