Anti-aliasing in a resin slicer feathers the edges of each layer image with shades of gray, so pixels that the model only partly covers receive partial light and the stair-steps on slopes and curves look smoother. For most miniature work, leave it on at a low setting: in CHITUBOX start with Image Blur at 2 (the low end of its range, our suggested starting point), and in Lychee use the Smooth Surface mode with a radius of 2 pixels on a 50 micron printer or 3 on a 35 micron one.
Higher settings give smoother edges but soften micro detail, and anti-aliasing only works inside each layer image. It does not remove layer lines, which depend on layer height. This guide explains what the gray level, blur and anti-aliasing modes in CHITUBOX and Lychee do, how they interact with exposure, when to turn them down, and how to test them. The definitions and values come from CHITUBOX and Lychee documentation, linked at the end.
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Anti-aliasing in 5 steps
- Check your printer’s XY pixel size (in microns) in its specifications.
- Slice with anti-aliasing at the low starting value from the table below.
- Print a test with curves, fine text and small holes, and look at it under a magnifier.
- Change only one setting at a time: blur, gray level or mode.
- Re-run an exposure test if edges look swollen or soft after the change.
What anti-aliasing, gray level and blur do
A resin printer’s light source is a grid of square pixels, and each layer is sliced into an image of those pixels. Without anti-aliasing every pixel is fully on or fully off, so a diagonal edge becomes a staircase of tiny squares. With it, the slicer paints the edge pixels in intermediate grays. A gray pixel passes less light, so the resin under it is cured less, and the edge transitions more gently.
The terms overlap, so here is how the two slicers use them:
- Gray level. In CHITUBOX it sets the range of grays available for anti-aliasing on a 0 to 255 scale, where 0 is black and 255 is white. CHITUBOX describes it as reducing triangular sawtooth by feathering the edges of the sliced image for LCD printers.
- Image blur. An extra softening step applied on top of the gray level. CHITUBOX gives it a range of 2 to 8 pixels for the edge transition; a higher value gives softer edges.
- Anti-aliasing level (legacy). The older CHITUBOX mode for the .cbddlp format with values 2, 4 and 8. A higher level means a longer edge exposure, sharper edges and a weaker anti-aliasing effect.
- Smooth Surface, Sharpen Details, Contrast Blur. Lychee’s modes. Smooth Surface applies anti-aliasing to the layer edges and then a slight blur of a few pixels. Sharpen Details is Lychee’s historical mode with very sharp details. Contrast Blur mixes the two.
All of these act within the plane of a layer. The layer thickness itself stays whatever you set, which is why a ridged surface on a gentle slope is a layer height problem; see resin layer height. CHITUBOX’s transition layers are a different feature: they ramp the exposure from the bottom layers down to the normal value, not smooth the model’s surface.
Settings by slicer
| Slicer and setting | Documented range or values | Notes |
|---|---|---|
| CHITUBOX: Gray Scale Level (.ctb) | 0 to 255; sets the gray range for anti-aliasing | Current mode for the .ctb format |
| CHITUBOX: Image Blur Pixel | 2 to 8 | Higher means softer edges; start at 2 |
| CHITUBOX: Anti-aliasing Level (legacy, .cbddlp) | 2, 4 or 8 | Higher means longer edge exposure and a weaker effect |
| Lychee: Off | Default | Documentation notes anti-aliasing matters less under 35 microns of pixel size, but stays relevant for fine-detail models |
| Lychee: Smooth Surface | Recommended mode for maximum anti-aliasing | Radius 2 px for a 50 micron printer, 3 for a 35 micron printer |
| Lychee: Sharpen Details | Level often at its maximum | Very sharp, some aliasing can remain depending on the resin |
| Lychee: Grey offset | No fixed value; tune per resin | Sets the gray value where anti-aliasing starts and the contrast of the grays |
| Lychee: High Definition Anti Aliasing | Strongly recommended | Longer export and more GPU memory; may lose the 3D view on some machines |
| Lychee: Anti-aliasing on supports | Off by default | Leave off so fine support tips are not thinned |
Other slicers, including the ones that ship with printers, use similar names. Check what they call the equivalent setting and what range it takes before you copy values from here.
How it interacts with exposure
Anti-aliasing changes how much light the edge pixels deliver, so it shifts where the edge of the cured part ends up. Lychee advises tuning the gray offset to each resin’s response to UV light and notes results depend on resin and exposure time. Our practical reading of that: treat a change of blur or mode like a change of resin and check a calibration print afterwards.
Too much blur and too much exposure look alike: text fills in, small holes close, thin pins swell. Too little exposure with strong blur looks like soft, rounded edges and weak thin features. If the symptom appears right after you raise blur, lower blur first. If it was there before, recalibrate with the exposure test; the exposure guide lists test prints that show both problems.
A reasonable starting point, which is our suggestion built on the documented values and not a maker recommendation: blur 2 in CHITUBOX; Smooth Surface with the radius matched to your pixel size in Lychee; High Definition on if your computer copes; supports left alone.
When it helps and when it softens detail
| Situation | Direction | Why |
|---|---|---|
| Miniature with smooth curves, about 50 micron pixels | Anti-aliasing on, low blur | Hides the pixel staircase on spheres, faces and folds |
| Very small text, thin pins, tiny holes | Lower blur or Sharpen Details | Lychee notes a larger radius loses definition of micro details |
| High-resolution screen, about 35 microns or finer | Often little needed | Lychee notes anti-aliasing is less needed below 35 microns |
| Parts with tight tolerances | Keep blur low and measure | Edge softening and exposure both move dimensions; calibrate on a fit test |
| Support structures | Anti-aliasing off | Avoids thinning support tips (Lychee) |
| Large flat faces | No visible benefit | Anti-aliasing works on edges, flat areas have none to soften |
If you are still choosing a printer, the SLA, DLP and MSLA comparison explains why MSLA pixel size sets how visible the staircase is.
Diagnosis: what you see and what to change
| Symptom | Likely cause | What to change |
|---|---|---|
| Stair-steps visible on slopes and curves | Anti-aliasing off or too weak | Turn it on; CHITUBOX Image Blur 2, Lychee Smooth Surface |
| Horizontal ridges across a curved surface | Layer height, not pixels | Use a thinner layer, see the layer height guide; anti-aliasing will not fix it |
| Soft, rounded text and edges | Blur or radius too high | Lower blur one step, or try Sharpen Details |
| Holes closed, pins swollen | Overexposure, possibly made worse by blur | Lower blur, then recalibrate exposure |
| Fine support tips thin or breaking | Anti-aliasing applied to supports | Switch it off for supports in Lychee |
| Slow export, 3D view lost in Lychee | High Definition anti-aliasing load | Turn the option off for large models, or close other GPU-heavy programs |
Mistakes to avoid
- Expecting anti-aliasing to remove layer lines. It smooths edges inside one layer image only.
- Changing blur and exposure together, so you cannot tell which one made the difference.
- Copying settings from a forum post for another printer or resin. CHITUBOX and Lychee both say results depend on the resin and the exposure.
- Keeping heavy blur on a model with fine text or small tolerances.
- Leaving anti-aliasing on for supports in Lychee, where the documentation recommends off.
When you are starting out with a new printer, set up the basics first with the first resin print guide, then come back to these edge settings once exposure and plate adhesion are stable.
Frequently asked questions
Should I turn anti-aliasing on for resin printing?
For miniatures and anything with smooth curves, yes, at a low setting. Lychee notes it matters less on screens finer than 35 microns, and recommends leaving it off for supports. If your parts need tight dimensions or have tiny text, keep the blur low and test.
What is the difference between gray level and image blur in CHITUBOX?
Gray level sets the range of grays, from 0 to 255, that the slicer can use to feather the edges. Image blur is a further softening of those edges across 2 to 8 pixels, and a higher value gives softer edges. Both reduce stair-steps and both can soften fine detail if pushed.
Does anti-aliasing remove layer lines?
No. It works inside each layer image, so it smooths the staircase on a layer’s edges, not the steps between layers. Layer lines depend on the layer height you chose.
Do I need to recalibrate exposure after changing anti-aliasing?
It is worth checking. Anti-aliasing changes how much light edge pixels receive, and Lychee points out that results vary with resin and exposure time. Print your usual calibration model and compare the fine features before and after.
