When LightBurn's built-in trace is enough, and when it isn't

Trace Image (Tools › Trace Image, or Alt/Option+T) works on brightness. Every pixel between the Cutoff and Threshold values, 0 to 128 by default, black to medium grey, becomes part of the shape, and the outline around those pixels becomes vectors. Ignore Less Than drops specks, Smoothness moves the result between straight lines and curves, Optimize trims the node count, and Sketch Trace handles photos of pages with uneven lighting. LightBurn 2.2 added Center Line Trace, which follows the middle of a line instead of both its edges. All of it is in LightBurn's Trace Image reference.

When LightBurn introduced the feature in 2018, it licensed Potrace, the tracing engine Inkscape uses. Tracer's one-colour trace is built on Potrace as well. For a black-and-white logo, expect the same kind of outline from both. What decides the result is the image you start from.

LightBurn's documentation names the images it traces best: those with "high contrast or well-defined edges, including logos, silhouettes, cartoons, sketches, and handwriting." That covers most of what a small shop cuts.

The advice from LightBurn's own team on the forum is sound, and it applies to every tracer:

• —Start from a big enough image. Scaling a small image up inside LightBurn before tracing changes nothing: the trace still works from the original pixels.
• —Don't trace text if you can find the font. Traced text rarely looks right unless the source is very high resolution.
• —Clean up nodes in LightBurn. Optimize Shapes is the staff's answer to traced artwork with too many points.

If your image fits, there is nothing to gain by leaving LightBurn.

Trace Image is one-colour by design. LightBurn's lead developer has said so plainly: "The trace engine currently only accepts 1-bit data" (forum). A colour logo is reduced to brightness, and every colour darker than the threshold becomes the same shape.

You can get around that by hand: trace again with a different Cutoff and Threshold to pull out another band of brightness, once for every layer you need.

A colour tracer does that step for you. Tracer's Auto and Detailed styles don't work on brightness: they pick the image's colours themselves, up to 12 and 16 unless you set another count under Colours, from 2 to 24, and give you an SVG with one shape per colour, so a red and a blue of the same lightness stay apart. Its Clean / Flat style still splits the image into four bands of brightness, and shares the blind spot of the manual method: those two colours can come back as one. When LightBurn imports an SVG it matches each colour to the closest colour in its palette, and that colour is the layer the shape lands on. Look at the layers after the import: two close colours can end up on one layer.

Two things to know before you engrave such a file.

• —Count the layers. On flat artwork Auto and Detailed give about one layer per colour, and a white background counts as one. On a busy image they can reach 12 and 16, or the count you set. Clean / Flat normally gives four, with near copies among them when the artwork has fewer colours. Delete the ones you don't need.
• —The layers are stacked. Each one covers its own colour and everything above it, the way a sign painter works back to front. Engrave every layer as a fill and the overlapping areas get engraved more than once. If that's not what you want, take the upper shape out of the lower one with LightBurn's Boolean Subtract.

Here a separate tracer doesn't help, and LightBurn says why. Tracing "results in an estimation of the image, and often the results from using Threshold image processing mode are better" (Images vs. Vectors), and for "smoothly shaded images, like photos" the docs point to Dither.

The same is true of Tracer. Its colour tracing can't reproduce a smooth gradient: it breaks it into flat bands. Engrave the photograph as an image.

LightBurn imports AI, SVG, DXF, PDF and PLT/HPGL, and PNG, JPG, BMP, GIF and TIFF images; version 2.2 adds WebP. Two formats you'll meet aren't on that list:

• —PSD. A client's Photoshop file. Tracer reads it when it was saved with its flattened image inside (Photoshop's Maximize Compatibility), and gives you an SVG or a DXF that LightBurn opens.
• —HEIC. What an iPhone saves pictures as. Tracer reads it in Safari, which decodes HEIC itself; in other browsers save it as JPG or PNG first.

EPS is a third, and neither tool helps there: LightBurn can't import it, and Tracer writes EPS but doesn't read it. Open it in a vector editor such as Inkscape and save it as SVG.

If you want to see what a colour trace gives you, Tracer exports SVG for free with an account. DXF is on the Pro plan.