LaserCanvas
Vector and raster: why a JPEG cannot be cut
A vector file stores lines and curves as maths, so a laser can follow them — SVG, DXF, AI, PDF. A raster file stores a grid of pixels, which can only be engraved. You can trace a raster into vectors, but tracing guesses, and it guesses worst on exactly the low-quality images people usually want traced.
Two ways to store a picture
| Vector | Raster | |
|---|---|---|
| Stores | Points, lines and curves as coordinates | A grid of coloured pixels |
| Formats | SVG, DXF, AI, EPS, PDF | JPG, PNG, GIF, BMP, most PDFs from a scanner |
| Scaling | Perfect at any size | Blurs or blocks up when enlarged |
| Laser can | Cut, score or engrave | Engrave only |
| Good for | Anything with an outline | Photographs and textures |
The reason for the last row is simple: to cut, the machine needs a path to follow. A vector file *is* a list of paths. A raster file is a description of colour at each point, with no lines in it at all — the lines you see are an impression created by adjacent dark pixels.
Tracing, and what it costs
Tracing — sometimes called vectorising — looks at a raster image and generates paths around regions of similar colour. It is genuinely useful and it is always a guess.
- It follows pixel edges, so a low-resolution image produces visibly stepped or wobbly outlines.
- JPEG artefacts become geometry. Compression noise around a hard edge gets traced as real detail.
- It cannot recover what is not there. A logo saved at 200 pixels wide has no crisp edges to find.
- It usually simplifies. Smoothing tidies the wobble and, in doing so, shifts the outline slightly — fine for decoration, a problem for anything that has to fit.
Trace when you have no alternative, and redraw when accuracy matters. For simple shapes, drawing over the image by hand takes less time than cleaning up a trace.
Asking for the right file
When a client sends a logo as a PNG from their website, the useful request is specific:
- "Do you have the original vector — an AI, EPS, SVG or vector PDF?" Whoever designed it had one.
- If not: "the largest raster you have" — an original at 3000 px traces far better than a 400 px web copy.
- For text, ask which font it uses. Retyping and outlining beats tracing letterforms every time.
Which to use for what
| Job | Use | Why |
|---|---|---|
| Cutting any shape | Vector | The machine needs a path |
| Score lines, fold lines | Vector | Same |
| Text | Vector, outlined | Sharp at any size; engraved raster text looks soft |
| Logos | Vector if at all possible | Edges are the whole point of a logo |
| Photographs | Raster | Continuous tone is what raster is for |
| Textures and shading | Raster | Dithering handles it; vectors cannot |
One file can hold both
A job often wants both at once: a vector outline to cut the part, a raster image engraved on its face. That is normal, and the two go on separate layers with separate operations — engrave first while the part is still held by the sheet, cut last.
Common questions
Can I laser cut a JPEG?
Not cut, only engrave. A JPEG stores pixels rather than paths, and a laser needs a path to follow. You can trace it into vectors first, but tracing guesses at where the edges are, and the result is only as good as the image you started from.
What file format is best for laser cutting?
SVG or DXF for anything to be cut, because both store real paths and both are widely supported. SVG carries units and colours well; DXF is the CAD convention and is millimetres by default. AI and vector PDF work too, though support varies more between tools.
Why does my traced logo have wobbly edges?
Because the tracer is following the boundaries between pixels, and at low resolution those boundaries are stepped. JPEG compression makes it worse by adding noise around hard edges, which gets traced as if it were detail. A higher-resolution source helps; redrawing helps more.
Should I convert my photo to vector before engraving it?
No. Photographs are exactly what raster is for, and a laser engraves them by dithering the tone into dots. Vectorising a photo throws away the continuous tone that makes it look like a photograph, and gives you a posterised outline instead.