Changing web radio and Airplay artwork

[dom.efendi]

One or two years ago I read somewhere a little guide on how the web radio and AirPlay artwork can be changed. I reinstalled rune yesterday and I forgot of course how it was done.
I can't seem to be able to find the folder where those artwork files are stored. Can anybody help please ?

[westrock2000]

Talking about this picture?



/var/www/assets/img/airplay-cover.jpg

[dom.efendi]

[graceinc]

Why is there a need for the artwork that too specific, would not any other similar artwork do? Novice.