\documentclass[a4paper]{article}

\usepackage{pgfplots}

\pgfplotsset{compat=1.8}


\begin{document}

%\tracingcommands=2\tracingmacros=2
\fbox{%
	\begin{tikzpicture}
	\begin{axis}[
		hide axis,
	]
	% this is a different impl than for bicubic
	\addplot3[surf,shader=interp] {x*y};
	\end{axis}
	\end{tikzpicture}%
}



\end{document}

