How does beamer handle background canvas template resolution when used within the title page template?
Background
I am working on adapting my company's PowerPoint presentation to use beamer. I had success with a previous iteration of this task, but the new changes are causing me a bit of trouble. Specifically, the background has a logo in the bottom right of the frame for every slide except the title slide which has larger version on the left side of the slide. Reading over Section 8.2.7 of the manual and How does beamer build the frame?, it appears the background canvas is a good position for these. I defined the template
\defbeamertemplate*{background canvas}{mine}[1][]{% \ifstrequal{#1}{title}{ \tikz[remember picture, overlay] \node [anchor=north west, inner sep=0pt, outer sep=0pt] at (current page.north west) {\includegraphics[height=15mm]{example-image-a}}; \typeout{Title background} }{} \ifstrequal{#1}{title}{}{% \tikz[remember picture, overlay] \node [anchor=south east, inner sep=0pt, outer sep=0pt] at (current page.south east) {\includegraphics[height=15mm]{example-image}}; \typeout{Running background} } } Reading How to apply \setbeamertemplate inside a beamertemplate, I see I need to set and use the template in my title slide
\defbeamertemplate*{title page}{mine}{ \setbeamertemplate{background canvas}[mine][title] \usebeamertemplate*{background canvas} \inserttitle } Unfortunately, this results in the logo in the bottom right to appear on the title slide. I know I could use \setbackgroundtemplate within a group to get the desired behavior, but I would like for end users to be able to just \maketitle or \begin{frame}\titlepage\end{frame} per the manual.
Digging further, when I use \typeout to see which branches are used in the background canvas, I see that it is set twice: once with the title argument and once without. I have tried using the background template with no better success.
Ultimately, I would like to know how to suppress the logo on the bottom right in the background canvas on the title page, but I am also curious about how beamer resolves the background canvas template.
Full MWE
\documentclass{beamer} \usepackage{tikz} \usepackage{mwe} \title{Notice the lower right image should not be on the title frame} \defbeamertemplate*{background canvas}{mine}[1][]{% \ifstrequal{#1}{title}{ \tikz[remember picture, overlay] \node [anchor=north west, inner sep=0pt, outer sep=0pt] at (current page.north west) {\includegraphics[height=15mm]{example-image-a}}; \typeout{Title background} }{} \ifstrequal{#1}{title}{}{% \tikz[remember picture, overlay] \node [anchor=south east, inner sep=0pt, outer sep=0pt] at (current page.south east) {\includegraphics[height=15mm]{example-image}}; \typeout{Running background} } } \defbeamertemplate*{title page}{mine}{ \setbeamertemplate{background canvas}[mine][title] \usebeamertemplate*{background canvas} \inserttitle } \begin{document} \begin{frame} \titlepage \end{frame} % Functional, but wordy for an end user \bgroup \title{This is the expected title background} \setbeamertemplate{background canvas}[mine][title] \begin{frame} \titlepage \end{frame} \egroup \begin{frame} The second frame \end{frame} \end{document} 
