PNG

A raster image format. Quality decreases when resized.

SVG

A vector image format. Can be resized without loss of quality. SVG-images can be edited and converted into PNG images using the free program Inkscape.
Hint: The generated SVG image contains many groups. Before editing the image, it is recommended to remove these groups. In Inkscape, use Edit > Select all (CTRL+A), then Object > Ungroup (CTRL+SHIFT+G) to remove the groups. Repeat several times.