Perspective correction using GIMP
Sep 16 2017 Sat
1:23 am PHT
As I mentioned on Facebook, a micro-hobby that I picked up recently is applying perspective correction on photos of NHCP historical markers in Wikimedia Commons such that they look as if they were photographed head-on and with horizontal edges looking horizontal and vertical edges looking vertical. An example result is the corrected photo of the Fort of San Pedro historical marker shown below.