Beamer title page with certain background and different background for the rest of the frames

Question

I have a the below code, that sets the logo on left top corner of the title page, however, I want to change the entire background of the title page to a the new UDBackground2.jpg figure. How is it possible to achieve that.

Also for the rest of the frames I want the background to be the name of the \author repeated. I tried to do that several times but it is not working, I would appreciate the help.

\documentclass[9pt,aspectratio=169,xcolor=table]{beamer}
\setbeamerfont{title}{series=\bfseries, parent=structure}
\institute{UUUUUU}
\titlegraphic{\hfill\includegraphics[height=1.1in]{logo}}   
\title{\color{black}XXXXXX }
\author[\underline{{\calligra \color{black} {yyyyy}}}] {yyyy }
 
\addtocounter{framenumber}{-1}
\renewcommand{\familydefault}{\rmdefault}
\setbeamercolor{section number projected}{fg=}
\makeatletter
\AtBeginPart{%
\beamer@tocsectionnumber=0\relax
\setcounter{section}{0}%
}
\setbeamercolor{frametitle}{fg=black}

\pgfdeclareimage[width=\paperwidth]{mybackground}{UDBackground2.jpg}
\begin{document}

 \defbeamertemplate*{title page}{customized}[1][]
{

\hfill \usebeamercolor[fg]{titlegraphic}\inserttitlegraphic \par \bigskip
  \usebeamerfont{title}\inserttitle \par
  \usebeamerfont{subtitle}\usebeamercolor[black]{subtitle}
  \color{black}{ \rule{\paperwidth}{1.4pt} }\\
  \color{black}
  \usebeamerfont{author}\insertauthor\par
%  \usebeamerfont{institute}\insertinstitute\par
%  \usebeamerfont{date}\insertdate\par
  
}
  \maketitle
  
   %% defines the header \hrule
 
\setbeamertemplate{frametitle}[default][left,leftskip=0.8cm]


\addtobeamertemplate{frametitle}{}{%
\begin{textblock*}{100mm}(0.9\textwidth,-0.7cm)
{\transparent{0.8}\includegraphics[height=1cm,width=1cm]{logo}}
\end{textblock*}   \par\hspace*{-\dimexpr0.5\paperwidth-0.5\textwidth}\color{black}\rule{\paperwidth}{1.4pt}}



\begin{frame}

\end{frame}

\end{document}

Answer 1

If you make the changes to the background within a group around the title frame, it will leave the background of the other frames alone:

\documentclass{beamer}

\begin{document}

\begingroup
  \setbeamertemplate{background canvas}{\includegraphics[width=\paperwidth,height=\paperheight]{example-image-duck}}
  \begin{frame}
    \titlepage
  \end{frame}   
\endgroup

\begin{frame}
content...
\end{frame}
    
\end{document}