White underbase

A white underbase you can see before you print.

NestSheet derives the white from the artwork’s alpha and puts every lever in your hand — choke, threshold, mode, amount, halftones — with a split preview of the exact channel your RIP receives.

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White Underbase Lab in the Prep terminal: Standard/Soft-Hand mode toggle, white amount, choke and alpha threshold sliders, live coverage numbers, and a before/after split of colour art against the generated white channel — The White Underbase Lab: every lever, with a draggable split of the channel itself.

The halo test

Where the white outline comes from.

White that prints wider than the colour above it shows as a pale edge on dark garments. Choke pulls the white in — and the preview shows exactly how far.

The white channel is derived from the artwork’s alpha — no hand-masking in Photoshop, nothing to forget on piece 37 of 43.
Choke erodes the white edge inward by 0–10 px; the default is 2 px. At 300 dpi, 2 px is roughly 0.17 mm — enough to hide small registration shifts without visibly shrinking the art.
The alpha threshold (0–255) decides how faint a pixel still earns white — your lever against remove-bg leftovers and semi-transparent edges.
The pair below is the same artwork at choke 0 and choke 2 px — the halo test, on the actual generated channel.

Split preview at choke 0: the generated white channel reaches the exact artwork edge, shown against the colour art — Choke 0 px: white to the exact art edge — any press shift shows as a halo.

Split preview at choke 2 px: the white channel edge pulled inside the colour edge, same artwork and split position — Choke 2 px (the default): the edge tucked under the colour.

The Lab

Tune it like a press setting, not a Photoshop ritual.

The White Underbase Lab lives in the Prep terminal: mode, white amount, choke and threshold, with live coverage numbers and a draggable before/after split of the channel itself.

Standard mode lays solid white under every qualifying pixel; soft-hand runs a 4×4 Bayer dither that keeps ~70% of white pixels for a lighter hand on thin fabrics.
White amount scales the whole channel, 0–255 — for garments that want a thinner base overall rather than a choked edge.
Coverage and choked-pixel counts update live, so you see what a setting costs before film does.
Mode “none” exists too — the underbase is a choice per export, not a default you fight.

Halftones

Three halftone methods for the white itself.

Gradients and fades need a white base that fades with them — solid white under a soft edge prints as a hard-edged slab.

Ordered, Floyd–Steinberg or stochastic dithering, dot size 1–24 px — applied to the white channel using the artwork’s alpha as density.
Halftoned white is how semi-transparent artwork keeps its softness on a dark garment instead of gaining a solid slab underneath.
You preview the dithered channel itself, not an artist’s impression of it.

In the file

The white you previewed is the white that ships.

At export the same tuning is written into the press file: TIFF with the white as extra channels, or PSD/PSB with real spot channels — named W1 onwards and renameable to your RIP’s convention. The preview shows the generated channel, so “looked fine on screen” still holds at the press. The full format matrix lives on the export page.

Spec sheet

The underbase parameters, from the code.

Every value below is read from the shipped product, not from a wishlist — the sources are in this page’s code.

White underbase parameters as shipped
Parameter	As shipped
Source	artwork alpha channel
Choke	0–10 px, default 2 (≈ 0.17 mm at 300 dpi)
Alpha threshold	0–255
Modes	Standard / Soft-hand / None
Soft-hand	4×4 Bayer dither, ~70% of white pixels kept
White amount	0–255, scales the whole channel
Halftone	Ordered / Floyd–Steinberg / Stochastic, dot size 1–24 px
Output	TIFF extra channels or PSD/PSB spot channels, named W1… (renameable)
Preview	draggable before/after split + live coverage counts

FAQ

The questions operators actually search.

Why is there a white outline on my DTF print?

The white underbase is printing wider than the colour above it — either it was generated straight from the alpha with no choke, or the layers shifted slightly in the press. Choking the white pulls its edge inside the colour edge, so small shifts stay invisible. NestSheet defaults to a 2 px choke.

What choke setting should I use?

Start at the default 2 px and judge the split preview at 1:1. Fine linework and small text may want less; big solid shapes on dark garments can take more. The range is 0–10 px — at 300 dpi one pixel is about 0.08 mm, so 2 px pulls the edge in roughly 0.17 mm.

Why do my prints look faded on dark shirts?

On the prepress side, the usual culprit is a white base that is too thin. Check the white amount (0–255 — lower prints a lighter base), whether soft-hand mode is on (it deliberately keeps ~70% of white pixels — skip it when you want punch), and the coverage preview: if the channel looks grey where the art is solid, the base will be weak. If the file checks out, look at ink density and cure settings on the press.

How do I fix a dusty white halo?

A dusty halo is adhesive powder bonding where it shouldn’t: semi-transparent edge pixels — anti-aliasing, glow, remove-bg leftovers — quietly receive white underbase, and powder sticks to it. Raise the alpha threshold so faint pixels stop earning white, add choke, and check the edge in the split preview before you print.

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