User-specified positioning of caption

Question

For tuning reasons that I cannot detail here, I would like to be able to control the position of the caption of figures. My current code is as follows:

\begin{figure}[ht!]
\colorbox{red!10}{%
\parbox{\textwidth-2\fboxsep-2\fboxrule}{%
\centering\includegraphics{fig1}%
\caption{}%
\label{fig:ch1-1}}}%
\end{figure}

Is is possible to move the caption (which is here only Figure 1) to the top-left corner of the colorbox. I know that the float package offers similar possibilities but would like to know if there is a solution by hand.

Answer 1

Here is a marginal alternative to Herbert's answer that preserves some of the original vertical/horizontal spacing:

\documentclass{article}
\usepackage[demo]{graphicx}% http://ctan.org/pkg/graphicx
\usepackage{calc}% http://ctan.org/pkg/calc
\usepackage{xcolor}% http://ctan.org/pkg/xcolor
\usepackage{caption}% http://ctan.org/pkg/caption
\begin{document}
\begin{figure}[ht!]
  \colorbox{red!10}{%
    \parbox{\textwidth-2\fboxsep-2\fboxrule}{%
      \captionsetup{format=plain,singlelinecheck=false}
      \caption{}\label{fig:ch1-1} \removelastskip\vspace{\dimexpr-\baselineskip-\abovecaptionskip\relax}
      \centering\includegraphics{fig1}%
    }%
  }%
\end{figure}
\end{document}

Moving the \caption to above the \includegraphics places the caption above the image. The demo package option to graphicx is merely for illustration.

Answer 2

You can cretae a new macro for this:

\documentclass{article}
\usepackage[demo]{graphics}
\usepackage{xcolor,calc}
\def\Caption#1{\refstepcounter{figure}Figure~\thefigure: #1}
\begin{document}

\begin{figure}[ht!]
\colorbox{red!10}{%
  \parbox{\textwidth-2\fboxsep-2\fboxrule}{%
    \Caption{\label{fig:ch1-1}}\hfill
    \raisebox{-\height+0.7\baselineskip}{\includegraphics{image}}}}
\end{figure}

\end{document}