Convert PNG to SVG for Inkscape

Trace Bitmap is a threshold tracer. In a single scan it decides, pixel by pixel, what is inside the shape and what is not (by brightness, by edge detection or by reducing the colours), then wraps curves around the result. On clean, high-contrast art that is exactly right: a black logo on white, a stencil, line art scanned at 300 dpi. Speckles removes the small islands, Smooth corners rounds the steps and Optimize joins segments to cut the node count.

It runs out on three kinds of image, and they are the ones people most often bring to a cutter or a laser:

• Several colours. Multiple scans trace each colour band separately. Stacked, every lower band continues under the ones above it; tiled, the soft edge between two colours becomes a hairline gap. Both need cleaning before a blade or a beam follows them.
• JPEG artefacts and soft edges. A threshold follows the halo of off-colour pixels that compression leaves around every edge, so a straight edge comes out wavy.
• Photos. There is no clean boundary for a threshold to find, so the result is either one blob or thousands of fragments.

That is the gap this converter fills. Upload the PNG above, check the preview, and open the finished SVG in Inkscape to do what Inkscape is good at: editing, arranging, sizing and preparing the job for the machine. If your file is a JPG, JPG to SVG uses the same engine.

The files this converter returns share a simple structure, and it is what makes them easy to work with in Inkscape: filled paths and nothing else. No strokes, no groups, no text, no embedded bitmap. Every shape answers to the node tool straight away; there is nothing to unlink or release first.

A real example: a CC0 photo of a cut-metal rooster on a steeple, converted on our Cricut page with the background removed, came back as 17 filled shapes in 4 colours, 12.8 KB in all. Three colours were flat shades of navy. The fourth, on the body, was a two-stop linear gradient between two near-black tones, because a shaded area can come out as a gradient. Inkscape keeps it editable in Fill and Stroke (Shift+Ctrl+F), and one click on the flat colour button there turns it into a single colour, which is what most cutting and laser software expects.

The size needs one check. The file states its width and height in pixels without a unit, 920 x 570 for the rooster, over a drawing grid 2048 units wide. Inkscape reads a unitless size at 96 pixels per inch, so the rooster opens at 243.4 x 150.8 mm. Type the size you need into the W and H boxes, lock closed, before the file goes to a machine.

Once the shapes are in Inkscape, the last step depends on what reads the file next.

• Cricut Design Space or Silhouette Studio. Save with File > Save As and pick Plain SVG, which leaves out the editing data only Inkscape uses. Silhouette Studio needs the Designer Edition or higher to open an SVG; PNG to SVG for Silhouette covers the DXF route for the Basic Edition.
• A laser. Many laser programs decide what to do from how a shape is drawn. Glowforge, for one, engraves filled shapes and cuts or scores strokes. Every shape in this file is filled, so for a cut line remove the fill and give the shape a stroke in Fill and Stroke. SVG for Glowforge and SVG for laser cutting go further.
• CAM or CNC software that wants DXF. Inkscape can save a DXF, but SVG to DXF writes closed R12 contours with the units declared in the file, which older CAM programs open without asking.
• An embroidery machine. Digitize with Ink/Stitch, or skip that step with SVG to DST for Tajima machines or SVG to PES for Brother.

Two Inkscape habits save trouble on every job: Edit > Resize Page to Selection (Shift+Ctrl+R) so the page matches the artwork, and Path > Simplify (Ctrl+L) only in small doses, because each press moves the curves a little further from the shape you traced.