From the April 2011 issue

A different type of filter

June 2011: This technique is so elegant that you may hear yourself ask, "Who was that masked High Pass filter?"
By | Published: April 25, 2011
These before and after images show the results of using the author’s technique of masked High Pass filtering on astroimages. Tony Hallas

Some years ago, imagers discovered a new way to enhance the detail in an astrophoto that proved superior to the unsharp mask in Photoshop. Follow me through these steps to uncover the power of what I call masked high-pass filtering.