\begin{tikzpicture}[x=20bp,y=20bp]%
    \clip (0,0) rectangle (10,10);
    \path [draw,fill=black!25,ultra thick] (0,0) rectangle (10,10);
    \path let \p1=(2,0), \p2=(2.4,0), \p3=(.4,0), \p4 = (.48,0) in
       node at (5,5) {\sffamily\fontsize{\x1}{\x2}\selectfont \llap{1}$\times$\rlap{1}}
       node at (5,2) {\sffamily\fontsize{\x3}{\x4}\selectfont (Original size: 200$\times$200 bp)}
    ;
\end{tikzpicture}%
