Tuesday, September 29, 2020

Multi-Unsharp Mask Sharpening

Until recently I stacked solar system images with Autostakkert!3 and sharpened using wavelet sharpening with Registax. I don't like depending on Registax since it's no longer supported. I decided to experiment with multiple application of un-sharp masks to wavelet sharpen. This approach was inspired by an article "How Unsharp Masking and Laplacian Sharpening Work" by Keith Wiley

A series of Paintshop Pro commands can be saved as an editable Python Script. I saved and modified such a script with a for loop that performs  un-sharp mask repetitions. Number of cycles, radius and strength are settable parameters. A medium denoise it applied after the un-sharp mask cycles. After the script I applied chromatic aberration correction. 

Before and after sharpening images of the Copernicus crater appear below. These images were acquired on a night with the moon just below the celestial equator and with average to below average seeing. 

Eleven cycles of  un-sharp masking with radius 2 and strength 55 were applied followed by a median denoise with aperture 3.  Close examination of the post script image suggests using the Paintshop Pro built in chromatic aberration removal tool. 

Scripts have also been created for Jupiter and Saturn. More on these in the future as I'm still experimenting with settings. 

Before wavelet sharpening

After wavelet sharpening