Folgendes funktioniert jetzt für mich. Habe darüber 3774 Seiten ohne einen Fehler auslesen können.

Code:
if [ ! -f "${homedir}/file.tif" ]; then debug_scan="#00"; echo "Check #00"; convert -density 300 "$line" -blur 1x0.9 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#01"; echo "Check #01"; convert -density 350 "$line" -morphology Smooth Octagon:2 -blur 1x0.8 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#02"; echo "Check #02"; convert -density 350 "$line" -morphology Smooth Octagon:1 -blur 1x0.9 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#03"; echo "Check #03"; convert -density 310 "$line" -blur 1x0.9 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#04"; echo "Check #04"; convert -density 320 "$line" -blur 1x1.0 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#05"; echo "Check #05"; convert -density 350 "$line" -blur 1x0.9 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#06"; echo "Check #06"; convert -density 300 "$line" -blur 2x3.0 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#07"; echo "Check #07"; convert -density 400 "$line" -blur 2x1.5 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#08"; echo "Check #08"; convert -density 200 "$line" -blur 2x0.5 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#09"; echo "Check #09"; convert -density 400 "$line" -morphology Smooth Octagon:1 -blur 1x0.8 "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
if [ -z "${qrcode}" ]; then debug_scan="#10"; echo "Check #10"; convert -density 450 "$line" -negate -morphology Close Disk -negate "${homedir}/file.tif"; qrcode=`zbarimg -q --raw "${homedir}/file.tif" | grep -i "vertrag" | grep -o "[0-9]*$" | grep -E '\<[0-9]{6}\>'`; fi
Fertig ist das ganze noch nicht. Mit $debug_scan wird die Häufigkeit der genutzten Methoden gemessen um später weiter zu optimieren.