Easy script to convert a folder of PNGs to same-sized SVGs using potrace

png_to_svg.sh

#!/bin/bash

# Run this in a directory of PNGs (or change *.png to *.jpg, *.gif, etc)
# It will make SVGs with the same name, at the same size as the PNGs
#
# DEPENDENCIES: imagemagick, potrace, mkbitmap (included in potrace)
# Adjust the following settings to get better results:
OPTTOLERANCE=.2  # 0 for angular images
CURVETHRESHOLD=1 # larger for less segments

for file in *.png; do
  w=$(echo "scale=2; "$(identify -format "%[fx:w]" "$file")" / 72.0" | bc);
  h=$(echo "scale=2; "$(identify -format "%[fx:h]" "$file")" / 72.0" | bc);
  whargs="-W $w -H $h";
  bmpfile=`basename -s .png "$file"`.bmp;
  pbmfile=`basename -s .png "$file"`.pbm;
  svgfile=`basename -s .png "$file"`.svg;

  convert -flatten "$file" "$bmpfile" || exit;
  mkbitmap -s 1 "$bmpfile" || exit;
  rm "$bmpfile";

  potrace --tight -O $OPTTOLERANCE -a $CURVETHRESHOLD -u 100 -s $whargs $pbmfile || exit;
  sed -itemp 's/width="[0-9\.pt]*" height="[0-9\.pt]*"//g' "$svgfile" || exit;

  rm "$pbmfile";
  rm "$svgfile"temp;

  echo $file;
done;