#!/usr/bin/perl
use strict;
use warnings;

while(my $line=<DATA>)
{
  while($line=~/\\includegraphics\[.*?\]\{(.+?)\}/gc)
  {
    my $pfad=$1;
    print "Pfad: $pfad\n";
  }
}

__DATA__
\includegraphics[Optionen]{AAA/BBB} \includegraphics[Optionen]{AAA/CCC} bla bla bla
bla
bla
bla
bla
\includegraphics[Optionen]{BBB/CCC}
bla
bla
\includegraphics[Optionen]{DDD/EEE} bla bla bla \includegraphics[Optionen]{DDD/FFF}
bla
bla
bla
bla
bla
bla
bla
bla
\includegraphics[Optionen]{FFF/GGG}
bla
bla
bla
bla
bla
bla