Remove backgroundcolor of title bar in Rochester Beamer Theme

In the following minimal example, the title bar saying "Test frame" has a blue background:

\documentclass[compress, final]{beamer}
\usetheme[height=0mm]{Rochester}
\usecolortheme{dolphin}
\useinnertheme{rectangles}
\useoutertheme[footline=empty, subsection=true]{miniframes}

\begin{document}

\begin{frame}{Test frame}
\begin{block}<+->{Block}
Beamer is cool
\end{block}
\end{frame}

\end{document}


In my opinion, it really makes the slide look "heavy". How can I remove the background color?

-

\setbeamercolor*{frametitle}{bg=white}

put it into the preamble before \begin{document}
I'd rather use \setbeamercolor{frametitle}{bg=} as this also works if the background canvas has a color other than white. – diabonas May 2 '11 at 15:09