How to customize the position of the caption of an image?

Question

How is it possible to customize the position of the caption of an image so that it can be done with absolute coordinates or in relation with the image borders? (A part of the image does not provide any important information id est a blank piece of the image).

Desired output:

MWE:

\documentclass{article}
\usepackage{graphicx}

\begin{document}
\begin{figure}
\includegraphics[width=\textwidth]{drawing.pdf}
\caption{This is a very long caption describing features of the image or anything else, what it is important is that a sort of long caption and I don't like its position.}
\label{fig:drawing}
\end{figure}
\end{document}

MWE ouput:

Answer 1

\documentclass{article}
\usepackage{graphicx}
\begin{document}
\begin{figure}
  \includegraphics[width=\textwidth]{drawing}\\[-9ex]
  \begin{minipage}{0.7\textwidth}
    \caption{This is a very long caption describing features of the
      image or anything else, what it is important is that a sort of
      long caption and I don't like its position.}
    \label{fig:drawing}
  \end{minipage}
\end{figure}
\end{document}