Editing multiple album artwork

I have a number of Miles Davis ‘albums’ with no artwork, mainly bootleg live concerts. I would like to add my own image of Miles to replace the generic Roon grey diagonals image. I can see how to do so for an individual albums but not for a group of albums. Is there a way to do this?
As an aside, the generic Roon image for albums with no artwork is very dull - the grey diagonals. Is there any chance of replacing this with a more colourful/interesting generic image?

There is no way to do this for a group of albums at once in Roon. If you have a suitable picture you might be able to batch embed it into your files depending on file format and tagging software in use.

Thanks. I’ll give it a try.