\begin{tikzpicture}
	\node[anchor=south west,inner sep=0] at (0,0) 
	{\includegraphics[scale=0.5]{images/flowr.jpg}};
						
	\draw[blue, xstep=.2,ystep=.2] (0,2.4) grid (1,3.4);
	\draw[gray, fill=gray,opacity=0.6] (0,2.4) rectangle (1,3.4);
						
	\draw[blue,xstep=.2,ystep=.2] (3.5,0) grid (4.5,1);
	\draw[gray, fill=gray,opacity=0.6] (3.5,0) rectangle (4.5,1); 
						
	\draw[blue,xstep=.2,ystep=.2] (1.5,1.3) grid (2.5,2.3);
	\draw[gray, fill=gray,opacity=0.6] (1.5,1.3) rectangle (2.5,2.3);
\end{tikzpicture}
