\documentclass[a4paper,twocolumn]{article}
\usepackage[tmargin=3cm,bmargin=3cm]{geometry}
\usepackage[pdftex]{graphicx}
\usepackage{xcolor}
\usepackage{multido}
\usepackage{pict2e}
\parindent=0pt
\pagestyle{empty}
\begin{document}

\multido{\rA=0.0+0.1}{10}{%
  \definecolor{transparentblue}{rgba}{0,0,1,\rA}
  \definecolor{transparentred}{rgba}{1,0,0,\rA}
  \textcolor{transparentblue}{\rule{4cm}{4cm}}\hspace{-2cm}%
  \textcolor{transparentred}{\rule{4cm}{4cm}}\hspace{-4cm}{\huge\bfseries\rA}\\[0.5cm]
}
\newpage
\setlength\unitlength{1cm}
\multido{\rA=0.0+0.1}{10}{%
  \definecolor{transparentblue}{rgba}{0,0,1,\rA}
  \definecolor{transparentred}{rgba}{1,0,0,\rA}
  \begin{picture}(6,4)
    \put(2,2){\color{transparentblue}\circle*{4}}
    \put(4,2){\color{transparentred}\circle*{4}}
    \put(2,2){{\huge\bfseries\rA}}
  \end{picture}\\[0.25cm]
}

\end{document}