% output=pdftex

\starttext 

\setupcolors[state=start]

\definelayer[test][position=yes]
\defineoverlay[test][\composedlayer{test}]

\setupbackgrounds[page][background=test]

\useexternalfigure[koe 1][koe]
  [width=3cm,
   background=color,backgroundcolor=red,
   backgroundoffset=2cm]

\useexternalfigure[koe 2][koe]
  [width=3cm,
   background=color,backgroundcolor=green,
   backgroundoffset=2cm]

\input tufte 

\placefigure{}{\externalfigure[koe 1]} 

\input tufte 

\placefigure{}{\setlayer[test]{\externalfigure[koe 2]}}

\input tufte 

\placefigure{}{\setlayer[test][hoffset=-2cm]{\externalfigure[koe 2]}}

\input tufte 

\typefile{test}

\stoptext