Optimal filtering of solar images using soft morphological processing techniques

Abstract

Context: .CCD images obtained by space-based astronomy and solar physics are frequently spoiled by galactic and solar cosmic rays, and particles in the Earth's radiation belt, which produces an overlaid, often saturated, speckle.
Aims: .We describe the development and application of a new image-processing technique for the removal of this noise source, and apply it to SOHO/LASCO coronagraph images.
Methods: .We employ soft morphological filters, a branch of non-linear image processing originating from the field of mathematical morphology, which are particularly effective for noise removal.
Results: .The soft morphological filters result in a significant improvement in image quality, and perform significantly better than other currently existing methods based on frame comparison, thresholding, or simple morphologies.
Conclusions: .This is a promising and adaptable technique that should be extendable to other space-based solar and astronomy datasets.