The Raspbery Pi mothe board comes without an operating system. This needs to be copied onto the SD card. I began with Raspbian Stretch . I picked the full scale version because it needs most of the graphics components. The image file is copied onto an SD card (I used 32 gig size) using etcher. I installed numberous packages, including apzche2, php, imagemagick. Apache2 and PHP are required so that the pixframe can be an http server and respond to various commands from a control panel available to a laptop or smart phone.
As the configuration became more and more complicated I began to copy the image on the SD card to a file on my computer so that I could write it back to a second SD card. I was able to have a development pixframe, save the image, and then transfer it to my working model. For this I used Win32 disk imagerr. Here is a copy of the complete image including operating system, installed software and scripts as of April, 2019. This can be written to an SD card using Win23 Disk imager.