...

gefahrgutformular/gefahrgutformular.cls

@@ -33,7 +33,17 @@
 \RequirePackage{graphicx,pict2e,picture,eso-pic}
 \RequirePackage[ngerman]{babel}
 \RequirePackage{siunitx-PTB}
+
 \ifluatex\RequirePackage{luaimageembed}\fi
+\iffalse % Warum geht das nicht?
+\AtBeginDocument{%
+  \ifx\vl@SignatureGraphic\@empty    
+    \ifx\vl@SignatureGraphicBaseLXIV\@empty\else
+       \usepackage{luaimageembed}%
+    \fi
+  \fi
+}
+\fi
 
 \let\vl@tempdima=\@ovxx
 \let\vl@tempdimb=\@ovyy
@@ -63,7 +73,8 @@
 \newcommand*\vl@SignatureGraphic{}
 \newcommand*\SignatureGraphic[1]{\gdef\vl@SignatureGraphic{#1}}
 \newcommand*\vl@SignatureGraphicBaseLXIV{}
-\newcommand*\SignatureGraphicBaseLXIV[1]{\gdef\vl@SignatureGraphicBaseLXIV{#1}}
+\newcommand\SignatureGraphicBaseLXIV[1]{%
+  \long\gdef\vl@SignatureGraphicBaseLXIV{#1}}
 \newcommand*\vl@SenderAddress{}
 \newcommand*\SenderAddress[1]{\long\gdef\vl@SenderAddress{#1}}
 \newcommand*\vl@RecipientAddress{}

gefahrgutformular/test-gefahrgutformular.tex

@@ -25,7 +25,10 @@ Pfeiffer-vacuum SAS\\
   \item 6 Lecks; Druck \SI{1.5}{\bar}; UN 1046; Helium \dots
   \item 2 Lecks; Druck \SI{1.5}{\bar}; UN 1046; Wasserstoff \dots 
 }
+
 %\SignatureGraphic{SIG_Ute_Becker.png}
+
+% Die Verwendung von \SignatureGraphicBaseLXIV erfordert LuaLaTeX
 \SignatureGraphicBaseLXIV{%
 iVBORw0KGgoAAAANSUhEUgAABdoAAAGgCAYAAAC9hNWKAAAWGXpUWHRSYXcgcHJvZmlsZSB0eXBl
 IGV4aWYAAHjarZpnclw5loX/YxW9BLgLsxzYiNnBLL+/g8ySSqrqiuiJYUrM5OMzwDXHAHTnf//n