I did a small change in pngcat, and is working on Kobo Glo firmware 3.13.1
(maybe work in other devices...)
image resolution:
Glo: 758x1024
H2O/HD: 1080x1440
add your images(png) in folder
:
.ScreenSaver/yourDevice/suspend/
ex:.ScreenSaver/Glo/suspend/
original source:
http://github.com/frostschutz/Kobo
USE THIS PACKAGE AT YOUR OWN RISK!
sorry my English (google translator)