\documentclass[a4paper]{beamer}
\usepackage{graphicx,tikz,xcolor}
\usepgflibrary{shadings}
\pagestyle{empty}
\begin{document}
\definecolor{B}{RGB}{0,61,133}
\begin{frame}
\begin{tikzpicture}
\fill[
inner color=B!90!white,%
outer color=B!70!black,%
shading=radial,%
] (0,0) rectangle (4,4);
\node at (2,2) {\includegraphics[width=2cm]{image}};
\end{tikzpicture}
\end{frame}
\begin{frame}
\begin{tikzpicture}
\fill[
inner color=B!90!white,%
outer color=B!70!black,%
shading=radial,%
] (0,0) rectangle (4,4);