Recent Developments At JPL In The Application Of Digital Image Processing Techniques To Astronomical Images

Techniques developed for the planetary exploration program are being applied by the Image Processing Laboratory of JPL to other astronomical images. Plates of the galactic cluster Stephans Quintet were scanned and digitized. Faint nebulosity was enhanced by removing foreground stars and subjecting the resulting image to a high pass filter. Exaggerated true color images were generated by color representation of the ratios of calibrated images taken in red and blue light. Partial compensation for atmospheric degradation was accomplished with a positionally dependent convolution kernel based upon a Wiener noise-additive model. The signal to noise of the kernel was allowed to vary as a function of the local standard deviation. Photographs of Saturn were digitized and processed in an effort to obtain more information about the D-ring region. Because of the low signal level, straightforward enhancement techniques were not sufficient to bring out possible structure in this region. By transformation to a polar coordinate image, summation techniques were able to increase the apparent signal to noise of radially symmetric brightness elements. Spectra from several planets were digitized in an effort to quantify possible spectral shift as a function of position in the image. Each spectrum scan line was cross-correlated with the central scan line. From the results of this cross-correlation, a most probable spectral line tilt angle was determined.