Raster to vector for screen printing: turning a customer JPEG into plates

Why print shops end up vectorising

Almost nobody sends a print shop production art. They send a JPEG pulled off a website, a PNG exported from a phone app, a screenshot of a logo, or a design file at 72 dpi that somebody insists looks fine. Raster art is tied to the resolution it was made at: scaled up to print size the edges go soft, lettering picks up stair-steps on film, and JPEG compression noise that was invisible on screen becomes a fuzzy fringe on every edge once it is 12 inches wide. A clean vector path scales without introducing new pixel stair-steps, but an automatic path traced from a poor edge preserves its wobble and missing detail at every size. Cutters ultimately follow paths; many cutter applications can trace a raster on import, while an inspected SVG gives you those paths explicitly before the job reaches the device.

Separate first, then trace — not the other way round

This is the part general-purpose vectorisers get wrong for print work. Point an auto-trace at a full-colour bitmap and it returns a stack of overlapping filled shapes ordered by whatever the algorithm found convenient. That looks right on screen and is useless as separation: you cannot burn a screen from "the shapes that happen to be visible in this region", because a screen is one ink everywhere it appears in the design, including the eleven letters of a wordmark and the two small highlights nobody thought about. Here the separation happens first, in colour space, with perceptual clustering — so an ink is one plate wherever it occurs — and then each suitable flat plate is traced on its own. The plate is the unit. A successful trace is written as its own SVG in the same geometry as the others; empty, continuous-tone or overly complex plates stay raster-only and produce a manifest warning rather than a pretend vector.

Clean the bitmap before you trace it, or the trace inherits the mess

Tracing quality is decided before the tracer runs, and this is where most of the disappointment lives. A JPEG that has been emailed around a shop four times carries compression noise along every edge, and a tracer will faithfully reproduce that noise as wobble in the path — thousands of tiny nodes describing artefacts rather than artwork. Two things help, and both are free and run in this browser. Raise the tolerance so near-identical colours collapse into one ink instead of fragmenting a single edge into a dozen speckled plates. Then merge inks in the list until the plate count matches what you are actually going to burn or cut. If the art arrived on a background you do not want, remove it first — the same editor does that in a click — because a traced background is thousands of paths you will spend longer deleting than you saved by tracing. Look at the free raster plates before you pay for anything: a clean, genuinely flat plate is a candidate for tracing; a ragged or tonal plate is not. The resulting SVG still needs inspection, and the renderer can decline a trace that is empty or too complex.

When to redraw instead

Sometimes tracing is the wrong answer and the honest move is to say so. A tiny logo with fine lettering — a 200-pixel-wide brand mark that needs to print two inches — has no edge information left to trace; a tracer will produce lumpy approximations of letterforms and the customer will notice. That job wants somebody to set the type in the actual typeface and rebuild the marks as real curves. Likewise anything you will have to modify structurally afterwards: a trace gives you paths, not an editable design. Tracing is at its best on flat art that is large enough and clean enough to have real edges — which is most band merch, most sports lettering, and most of what actually comes through a shop.

Photographs and halftones: do not trace them

Tracing a photograph is a bad plan. Continuous tone has no edges to trace, so the tracer invents thousands of them and produces a file that is slower, larger and less faithful than the raster it came from — the posterised look people sometimes want from this is better achieved by separating deliberately with a low ink count. The same applies to halftoned plates: a dot grid traced to vector becomes tens of thousands of tiny circles with no gain in quality and a file your cutter software will choke on. For tonal work use index or simulated process separation and keep those plates raster. That is not a limitation of the tool, it is the right answer.

What you get, and what opens it

Every render includes raster PNG plates plus a manifest recording inks and geometry. With vector tracing enabled, each suitable plate also gets an SVG; the manifest and warnings identify any plate the tracer left raster-only. SVG is a common interchange format for Illustrator, CorelDRAW, Inkscape, Affinity Designer and cutter software, but inspect the imported paths and scale in the next application. The vector trace is an optional addition to the raster deliverable, not a replacement for it. Separately from the render, after free sign-in, the browser can export a multichannel PSD carrying one real spot channel per printable ink from a local Spot or Index result.

Free separation, paid trace

Load the art and separate it in your browser for free, with no account and no artwork upload; runtime depends on the image and device. Inspect whether the raster plates are clean before spending anything. The vector trace runs as part of the server-side print-ready render at 10 credits per image, with free re-renders of that image for 24 hours. After changing ink count or tolerance, run the free separation again to update the palette before re-rendering and tracing it. Credits come with a monthly plan, or as a one-off pack whose credits never expire — see the pricing page for current prices in your currency. No watermarks on any output, ever.

Successful traces can continue into cutting work

An SVG the optional tracer successfully emits can also feed layered vinyl, Cricut and laser projects: one path set per material colour, in the same geometry as the other plates. Empty, tonal or overly complex plates can remain raster-only, and an automatic trace is not a promise of cutter compatibility or clean paths. Inspect the SVG and its imported scale in the cutter application before sending a job. If you came here from cutting rather than printing, the separation logic is identical — you are just calling the inks materials, and deliberate overlap still belongs in the workflow you have tested on that material.