What's the best free tool to convert PNG to SVG?

Question

I've made 144 different PNG images. Now I want to convert (trace) them to SVG. What's the best free tool to make this?

IMPORTANT: The images consist of only black and transparent parts. Their sizes are 600 * 600 pixels. They aren't so complicated. Example:

P.S. I'm using Ubuntu 20 (operational system, a version of Linux). Maybe there's some good software for it?

Answer 1

Thanks, @Billy Kerr!

I saw the posts on StackOverflow (first and second) and figured out I'll need to use potrace.

First, convert PNG files to BMP, because potrace can work only with BMP. It is possible to do using an online site, but it's easier and always free offline.

To process multiple files using potrace, a bash script is needed:

#!/bin/bash

for filename in ./*.bmp; do
    for ((i=0; i<=3; i++)); do
        potrace --svg $filename
    done
done

The script iterates through all the elements of the current directory and converts them all to SVG using potrace.

But to use it in the terminal, first make it executable by writing

chmod +x [your filename].sh 

and then run it:

./[your filename].sh

After that, the terminal will work a bit, so don't worry, the images are processing - approximately half of a second per image.

Answer 2

You can't actually "convert" PNGs to SVG. It's not possible. There's no one to one mapping of raster images directly to vector images.

However, you can certainly auto trace raster images to make vectors, but results may vary and depend a lot on the kind of image, and the quality of the original, and the settings used in vector software. Inkscape which is free and Open Source has a Trace Bitmap feature.

For more high quality SVGs, or when a raster image is not good enough quality to auto trace, these often need to be hand crafted. Probably not what you want to hear, however the example image you posted looks good enough.

It may be possible to run Inkscape using the command line for a batch of images. Unfortunately I can't really help you there, but it's something you might want to research.

Answer 3

An alternative to the accepted solution which take as input an png file is

#!/bin/bash

if [ "$1" == "" ]; then
  echo Usage: $0 pngfile
  exit 0;
fi

FILE=`basename $1 .png`

if [ ! -e $FILE.png ]; then
  echo $FILE.png does not exist
  exit 1;
fi

convert $FILE.png $FILE.pnm
potrace -s -o $FILE.svg $FILE.pnm
rm $FILE.pnm

Usage:

./png2svg.sh image.png

will create image.svg

NOTES: Make sure potrace is installed on your system sudo apt install potrace

Found here https://gist.github.com/ykarikos/2892009 along with other helpful