Como crear un mosaico de imagenes en un PDF

crear-mosaicos.sh

DPI=300
# Como las dimensiones del A3 son 16.5x11.7 pulgadas, para poder hacer esto en shell:
X=165
Y=117
ANCHO=$(( $X*$DPI/10 ))
AlTO=$(( $Y*$DPI/10 ))
COUNT=0
FILES=""
DONE=0
SPACES=50

generate_multi() {
  [ -z "$FILES" ] && echo "no input files. Done!" && return
  if [ ! -e multi/multi-$(printf "%03d" $DONE).jpg ]; then
  montage $FILES -tile 2x2 -mode concatenate -geometry +$SPACES+$SPACES multi/multi-$(printf "%03d" $DONE).jpg
  else
  echo skip multi/multi-$(printf "%03d" $DONE).jpg
  fi
  DONE=$(( $DONE + 1 ))
}


for i in *jpg; do
  COUNT=$(( $COUNT + 1 ))
  FILES="$FILES $i"
  if [ $COUNT -eq 4 ]; then
    COUNT=0
    generate_multi
    FILES=""
  fi
done
generate_multi
for i in multi/*jpg; do
  convert $i -resize ${ANCHO}x${ALTO} -extent ${ANCHO}x${ALTO} -gravity center -units PixelsPerInch -density $DPIx$DPI multi/$(basename $i .jpg).pdf 
done