It
is free (as in no money changes hands), and may be a useful program for someone running MS Windows of some sort, but it's not open source, which implies greater freedom(s). Open source means you can download the source code, modify it for your own purposes, redistribute, etc.
See
http://opensource.org/docs/osd
No axe to grind, just clarifying terms. Photoscape might more accurately be described as "freeware".
Along the same lines, recent releases of LightZone for Linux have been changed to expire after a certain date, and it isn't really open source either, for the same reasons as Photoscape.
Lee