Hi, it took me a sec to wonder "What png?", but I had taken a screenshot using KDE's Spectacle of the Dolphin file manager displaying large icons. Spectacle's default file format is png. Sorry about that. It never occurred to me that would be confusing. The image of the thumbnails, which are all jpg, and the image of the gkrellm stack, are all done using Spectacle and are not included in the segment at all.
Thank you for pointing that out to folks.