Finely detailed striae in astronomical images can be important in formulation of theory. Examples are studies of streamers in the solar corona and of dust tails in comets. In both instances, conventional observations fail to reveal much of the structural detail. Digital image processing has been used at Los Alamos Scientific Laboratory (LASL) for enhancing these images. The corona images have tremendous variations in film density which must be eliminated before fine striae can be seen. These variations can be removed by means of numerical modeling of their spatial relation to the sun. This model can be thought of as a surface of background film density. In the comet images the overall variation is less severe. Further, the large number of comet images makes it infeasible to model them individually. Hence, an extreme low-pass filter was used to create an image which can be used as the background surface. In both cases, the background surface is divided into the original image pixel by pixel. This quotient image is then frequency-filtered for edge enhancement or noise control. Nonlinear density transformations are then used to enhance contrast. For both types of images, heretofore unmeasurable details become readily visible for analysis.
Walter Matuska, Jr.,
D. H. Janney,
J. A. Farrell,
C. F. Keller, Jr.,
"Enhancement of Solar Corona and Comet Details," Optical Engineering 17(6), 176661 (1 December 1978). https://doi.org/10.1117/12.7972301