TikZ scaling graphic and adjust node position and keep font size

Question

I have several pictures in my thesis. I want to draw arrows with text over these pictures. After that I want to scale the picture, but the node position should adjust to the scaling and arrows, and text-size should not change.

Here is my example:

\begin{figure}
\begin{tikzpicture}[
every node/.style={font=12pt},
remember picture,
scale=0.3,
transform shape
]
 \node[anchor=south west,inner sep=0] (Bild) at (0,0) {\includegraphics{images/Bild.eps}};
  \node (a) at (28,44) {Hello};
  \node (b) at (54,63) {};
 \draw [
 -latex,
  line width=2mm,
 ] (a) -- (b);
\end{tikzpicture}
\caption{This is an example} \label{Fig:Example}
\end{figure}

So when I scale with 0.3 the image Bild.eps is scaled, but also the font is scaled very small.

How can I scale the picture without changing the font and arrows while the node coordinates are adjusted to the scaled pictures (same position)?

Here is what I have so far:

    \begin{tikzpicture}
        \node[anchor=south west,inner sep=0] (image) at (0,0) {\includegraphics[width=1\textwidth]{Bild.eps}};
        \begin{scope}[x={(image.south east)},y={(image.north west)}]
                  \draw[
            -latex,
            line width=2mm
            ] (1,1) -- (3,2);
        \end{scope}
    \end{tikzpicture}

But I am working in TikZEdt. It is very hard to adjust the arrow by setting the nodes with the cursor. I got a very small green rectangle, which represents the size of the arrow.

How can I make this rectangle bigger so that it is easier to adjust/set the position of the nodes for the arrow?

Okay here is what I mean:

• Scale the picture
• Keep the arrow and font size (same as document size)
• Keep the position of the nodes

The picture is the output how I want it (I edited it with Photoshop).