My first idea would be to place the photo in a layer in the background.

I tried the following:
\definelayer[picture][
  preset=righttop,
]

\setlayer[picture]{\externalfigure[graphics/pasfotoKlein]}

\setupbackgrounds[page][rightedge][background=picture]

Whatever I do, the picture keeps in the top left corner of the page. I would like to have the right side of the picture aligned with the right margin. Is this possible?

\definelayer[picture][preset=righttop,width=\textwidth]

\setlayer[picture]{\externalfigure[mill][width=4cm]}

\setupbackgrounds[text][text][background=picture]