Any CO2 laser owner prepping artwork
How to prep a file before you engrave
Vector cuts · raster engraves
Prep the file — don’t trust the driver
A laser reads two kinds of artwork very differently. Vector paths tell the machine where to cut or score — it follows the lines. Raster images tell it how to engrave — it sweeps the image row by row like a printer, and how dark each pixel is decides how much power lands there. For engraving, that means the file prep is the job: convert the image to greyscale first and adjust contrast yourself, choose a dithering pattern suited to the material, and match your resolution to what the laser can actually resolve. Boss CO2 systems run standard raster/vector workflows, so this file prep applies whatever design software you use. Then test on scrap before committing to the final piece.
1 · Vector vs. raster: two different jobs
One artwork file often carries both a vector layer and a raster layer, and the laser treats them completely differently.
| Layer | What the machine does | Used for | Common formats |
|---|---|---|---|
| Vector | Follows a defined path with the beam | Cutting, scoring, and outlining | SVG, AI, DXF |
| Raster | Sweeps the image row by row, varying power with pixel darkness | Engraving photos, logos, and shaded artwork | PNG, JPG, BMP |
A single job — a plaque with a cut outline and an engraved photo inside it — usually combines a vector path for the outline with a raster image for the engraved area.
2 · Greyscale: how the engraver reads darkness
On a raster pass, the driver maps each pixel’s brightness to power or dwell time — darker pixels get more energy, lighter pixels get less. That mapping only works cleanly if you hand it a controlled greyscale image instead of a raw color photo.
- Convert to greyscale first, in your own software. Letting the driver do an automatic color-to-greyscale conversion gives you no control over which tones survive. Doing it yourself lets you see and adjust the result before it ever reaches the machine.
- Adjust contrast on purpose. Boost midtone separation so detail doesn’t collapse into a flat grey mass, and check both ends of the histogram before you commit.
- Blown highlights and crushed shadows don’t come back. If the very brightest areas are already pure white or the darkest areas are already pure black before you engrave, that detail is gone — the laser can’t recover information the file never had. Fix it in the image, not on the machine.
Why this beats “let the driver figure it out”
Auto-contrast and auto-greyscale settings are built to look reasonable across many images, not to protect the detail in yours. A wood-grain photo, a high-contrast logo, and a soft portrait all need different contrast handling — decide it yourself, in an image editor where you can see the histogram, rather than trusting a one-size-fits-all default.
3 · Dithering vs. true greyscale
Once the image is greyscale, the driver still has to decide how to turn shades of grey into laser pulses, since most engraving is really an on/off beam. There are two approaches.
- Dithering converts shades of grey into patterns of dots — more dots, or denser dots, read as darker from a normal viewing distance. It’s the industry-standard way to fake continuous tone with a beam that’s mostly binary, and it tends to hold up better on high-contrast materials like wood, where the material’s response to power in the midtones is less predictable than in the highlights and shadows.
- True greyscale (variable power / “3D” mode) actually varies the laser’s power or speed continuously across the image instead of dot patterns, carving visibly different depths for different tones. It suits depth-carved or sculptural work more than flat photo engraving.
Within dithering, two pattern families cover most engraving work:
- Error-diffusion patterns (Floyd-Steinberg and similar) scatter dots more randomly, which blends well with photographic detail and gradients — a natural fit for portraits and organic subjects, and for materials like wood where the grain already adds its own irregular texture.
- Ordered / halftone patterns place dots on a regular grid at an angle, which holds cleaner edges on logos, text, and simple graphics, and reads well both up close and from a distance.
Match the pattern to the subject, not just the material
As a starting point: error-diffusion (Floyd-Steinberg-style) dithering for photos and portraits, ordered/halftone dithering for logos and line art, true greyscale for depth-carved pieces. Every driver’s dithering options are slightly different — confirm the exact pattern names and settings in your own software before committing to a job.
4 · Resolution: matching DPI to the engrave
DPI (dots per inch) sets how many laser pulses fire across an inch on a raster pass; a related setting, LPI (lines per inch), sets how many passes the laser makes down the image. Neither one is a “more is always better” dial.
- Match your image resolution to your engraving DPI. If the source image has less detail than the DPI you’re engraving at, the driver is inventing pixels that were never in the file — you’re not gaining detail, just burn time.
- Higher DPI isn’t automatically higher quality. Push the resolution past what the material and lens can resolve and adjacent burns start to overlap, muddying fine detail instead of sharpening it — this shows up especially on wood, where the beam’s heat spreads slightly into the surrounding grain.
- Working ranges are material-dependent, not fixed. As a typical, non-Boss-specific reference point, wood generally needs a lower DPI than a harder, finer-grained surface like anodized aluminum, because each engraved dot is already larger relative to the wood’s texture. Treat any number you read — including the ones on this page — as a starting point for your own test, not a spec.
Resolution also drives job time directly — doubling DPI roughly doubles how long the engrave takes, so there’s a real cost to pushing it higher than the material needs.
5 · The material changes the prep
The same greyscale file behaves differently depending on what it’s landing on. Wood is the material most likely to fight you, because the grain adds its own texture and noise on top of whatever the image already has.
- Wood grain competes with fine detail. Boost contrast so the design reads clearly against the grain, and avoid leaning on very fine midtone detail — grain variation will compete with it and the result reads muddy rather than sharp.
- Photo engraving expectations shift by material. The same portrait that looks crisp on smooth acrylic will look softer and grainier on wood, and different again on anodized aluminum, which engraves as a clean bright-on-dark mark rather than a shaded photo tone.
| Material | Photo engraving result | Prep note |
|---|---|---|
| Wood | Warm, textured; grain adds visible noise | Boost contrast; keep dithering material-appropriate; skip very fine midtone detail |
| Acrylic | Smooth, high-contrast; holds fine tonal detail well | Frosted engrave reads cleanly; less contrast correction usually needed than wood |
| Anodized aluminum | Bright-on-dark mark, not a shaded photo tone | Treat more like high-contrast line art than continuous-tone photo work |
6 · The test-grid habit
Engrave a small test block — the same material, the same finish or coating, roughly the same grain pattern — before you run the final piece. A test grid of a few power/speed/dithering combinations on scrap catches a muddy dither pattern, a blown-out highlight, or a resolution mismatch while it still costs you scrap, not the finished piece.
Scrap first, always
This holds for every material and every file, not just wood. Settings that looked right on screen can still surprise you once actual power meets actual grain, grade, or coating — a two-minute test block is cheaper than redoing the job.
Frequently asked
Artwork & greyscaleQHow do I prepare a photo for wood engraving?
Convert the image to greyscale yourself rather than letting the driver do it, adjust contrast so detail survives the engrave, and apply a dithering pattern suited to wood — error-diffusion (Floyd-Steinberg-style) patterns tend to blend well with wood’s natural grain texture. Test on scrap to set the depth and resolution before committing to the final piece.
QWhat DPI should I engrave at?
There’s no single number — match your image’s actual resolution to the DPI you engrave at, and treat published ranges as a starting point, not a spec. Wood generally needs less DPI than a fine, hard surface like anodized aluminum, since each dot on wood is already larger relative to the grain. Pushing DPI past what the material and lens can resolve overlaps adjacent burns and muddies detail instead of sharpening it.
QShould I use dithering or true greyscale?
Dithering — converting tones into dot patterns — is the standard choice for photo engraving and holds up better on high-contrast, texture-heavy materials like wood, where the power response in the midtones is less predictable. True greyscale (variable-power) mode actually varies depth continuously and suits sculptural or depth-carved work more than flat photo engraving.
QWhy does my photo engraving look muddy?
Muddy results usually trace back to one of three causes: contrast that was too flat before you engraved (fix it in the image, not after), a DPI set higher than the material and lens can resolve (adjacent burns overlap), or a dithering pattern mismatched to the subject (fine error-diffusion detail lost in wood grain, for example). Work back through greyscale, dithering, then resolution to isolate which one is fighting you.
QWhat file format should I use for engraving artwork?
Raster formats — PNG, JPG, or BMP — for the engraved (shaded) portion of the design, and vector formats — SVG, AI, or DXF — for any paths you want cut or scored. Many designs use both in the same file: a vector outline plus a raster image engraved inside it.
7 · Related guides & next steps
- CO2 air assist — cleaner char control makes engraved detail easier to read once the file prep is right.
- Choosing a CO2 laser lens — the 2″ lens for fine-detail engraving work like photo and greyscale jobs.
- Cast vs. extruded acrylic — cast acrylic frosts bright for engraving, the acrylic-side counterpart to this guide.
Ready to put a file on the bed?
Match the machine to the detail you’re after.
Greyscale, dithering, and resolution get the file ready — the CO2 system underneath it determines how much of that detail actually survives the engrave. Tell a Boss Laser specialist what you’re engraving and we’ll point you to the right machine.