The SWAP Filter: A Simple Azimuthally Varying Radial Filter for Wide-Field EUV Solar Images

TL;DR

The SWAP Filter is a novel azimuthally varying radial filter designed to enhance wide-field EUV solar images, particularly improving the visualization of the low signal-to-noise middle corona.

Contribution

We introduce the SWAP Filter, a new data processing technique tailored for EUV solar images, with implementation details and demonstrated benefits.

Findings

Enhanced visualization of the middle corona in EUV images

Improved signal-to-noise ratio in wide-field solar observations

Effective for low signal-to-noise data environments

Abstract

We present the SWAP Filter: an azimuthally varying, radial normalizing filter specifically developed for EUV images of the solar corona, named for the Sun Watcher with Active Pixels and Image Processing (SWAP) instrument on the Project for On-Board Autonomy 2 spacecraft. We discuss the origins of our technique, its implementation and key user-configurable parameters, and highlight its effects on data via a series of examples. We discuss the filter's strengths in a data environment in which wide field-of-view observations that specifically target the low signal-to-noise middle corona are newly available and expected to grow in the coming years.