[rrd-users] Is it possible to modify the background image of the graph PNG file?

[Martin T]

Hi,
I have a very similar temperature monitoring graph to this one:
https://calomel.org/rrdtool_health.png ..and technically I'm pleased
to it, but I would like to change the background image of the graph.
How to achieve this? Which techniques might be used in order to add
logos or different backgrounds to graphs?

regards,
martin