documentclass{beamer}
usepackage{mwe} % example images
usepackage{lipsum} % example text

usepackage{tikz}
usetikzlibrary{calc}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% absolute positioning of typeset material
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
newcommand{placetextbox}[4][center]{%
  % [#1]: box anchor: center (default) |
  %                 south west | west | north west | north |
  %                 north east | east | south east | south |
  %                 mid west | mid | mid east |
  %                 base west | base | base east
  % #2: horizontal position (fraction of page width)
  % #3: vertical position (fraction of page height)
  % #4: content
  %
  tikz[remember picture,overlay,x=paperwidth,y=paperheight]{%
    node[anchor=#1,inner sep=0pt]
    at ($(current page.south west)+(#2,#3)$) {#4};
  }%
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

begin{document}
begin{frame}
  placetextbox[north west]{0}{1}{includegraphics[width=0.6paperwidth]{example-image-a}}
  %normal text
  lipsum[1]
  placetextbox[south east]{1}{0}{includegraphics[width=0.6paperwidth]{example-image-b}}
end{frame}
end{document}