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Guided workflow variation

Flat-color tee art,split into one plate per ink.

Most shirt orders are a few flat colors. Underbase reads the file, folds anti-aliased edges and near shades into the right ink, recognizes the background, and lists every plate with its coverage so you can rename, merge, reorder, or switch inks off.

Open the art, confirm the inks Underbase found, set the order and spreads, keep the job inside the plate budget, and generate the film pack.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Full Underbase overview
One-time purchase No telemetry Local-first

windows · runs on your pc · no account · nothing uploads · 15-day free trial

If this sounds like your week

Customer logos are never as flat as they look.

A three-color logo saved as a PNG can hold thousands of distinct pixel values. Smoothing along every curve creates in-between tones, export settings shift a red by a few points, and a white backdrop that is really the shirt sneaks in as a color. Sorting that by eye means picking each hue, deciding which tints belong to it, and remembering to drop the backdrop.

Where tooling usually breaks

Extra plates cost screens; missing ones cost reprints.

Treat two nearly matching reds as separate and you coat, expose, and register a frame you never needed. Lose the in-between edge pixels and letters print with a jagged outline or a hairline gap. Count wrong and the job turns out to need seven heads on a six-head press, which you learn while setting up instead of while quoting.

Where Underbase lands

Confirm the inks, then generate.

Underbase proposes the inks with Spot (flat colours): each exact color belongs to one ink, edge pixels are shared between neighbors, and close shades are grouped, shown as a hex value plus a shade count. The backdrop is set not to print. Rename from a stock list, merge, switch Print off, reorder with arrows, or use Reduce to. The budget tile tracks every screen.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Learn more about Underbase

windows · runs on your pc · no account · nothing uploads · 15-day free trial

What you get

Feature highlights

Spot or index separation from the files customers send

PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF, and Illustrator (.ai) files, with close shades grouped, the background left unprinted, and shaded art dithered between a fitted set of inks.

A choked white underbase

built from the inks you tick, pulled in from 0 to 3 mm in 0.05 mm steps, with dark inks printing straight on the shirt and a preview on seven garment colors.

Trapping in one click

spread or choke any ink from -3 to +3 mm, or apply the default trap to every ink so lighter colors tuck under the darkest.

Halftones tuned to your press

screen any plate at your ruling, angle, and tint, take a ruling suggested from the mesh, thin halftones for measured dot gain, and check the output dots before film.

A plate budget you can see

Underbase counts the underbase and every printing ink against the screens your press holds, holds generation until the job fits, and merges inks to fit in one click.

True-size film and a production ticket

a film PDF with identical registration marks and plate labels, one plate per sheet or ganged, 1-bit TIFFs at up to 1440 dpi, and a ticket as PDF and JSON.

Especially when

  • Turn a customer PNG, JPEG, SVG, PDF, or Illustrator file into one plate per ink without selecting colors by hand in a design program
  • Build a white underbase for dark shirts that is choked so it never shows at the edges, and keep dark inks off it
  • Know the plate count before burning a screen, and merge inks to fit the screens the press holds
  • Print film positives at true size with registration marks and plate labels, plus a production ticket, without sending the job to an outside separator

Who benefits

Real-world scenarios

A three-color surf logo for a retail order

A surf shop sends a 3,000 x 3,600 px PNG with navy, coral, and cream on a transparent background, to print 10 x 12 in on black tees.

Underbase reads 300 dpi from the file, sets the print size to 10 x 12 in, and lists Navy, Coral, and White with their coverage. Suggest print order puts the underbase first and the cream last as the highlight white, and Generate underbase pack writes 13 files.

A six-color mascot on a six-screen press

A school mascot arrives with six inks on a white background. With the underbase, the job needs seven screens, and the press has six.

The budget tile shows 7 of 6 plates in red, and generation waits. Merge inks to fit the budget merges the closest pair, or the operator picks Merge this ink into for a specific pair. The count drops to 6 of 6 and Generate underbase pack is ready.

One-color text with no resolution tag

A customer emails a one-color text graphic saved at screen resolution, with no print resolution in the file, for a 12 in wide back print.

Underbase flags that the file has no print resolution and assumes 300 dpi. The operator types 12 in the Print width field, and the height follows. The Source resolution field stays editable, so the art prints at the size the customer ordered.

Deep dive

Getting spot separations right before the first screen is burned

How inks are found. In Spot (flat colours), Underbase gathers the colors in the artwork, groups shades that are close to each other into one ink, and assigns the in-between pixels along anti-aliased edges to the inks on either side. Each ink in the Inks and plates list shows its coverage as a percentage, and the Selected ink panel shows its hex value plus how many shades it absorbed, for example #1B2A49 + 7 shades.

The background is not an ink. A color that fills the border of the image, such as a white backdrop on a JPEG, is set not to print, and a notice says it looks like the background. Turn Print back on if it really is an ink. Transparent PNG and TIFF backgrounds are left out automatically.

Name the inks the way the shop does. Type an ink name or pick one from the stock list, which holds names like Bright Red, Kelly Green, Royal Blue, Gold, and Highlight White. Change the Colour field to the hex value of the ink on your shelf. The names carry onto the film labels and the production ticket.

Merge and reduce. Merge this ink into folds one ink into another and its shades go with it. Reduce to merges the closest inks until the count you set is reached, from 1 to 16. When the plate budget is over, Merge inks to fit the budget does the same thing in one click.

Print order. Set the order with the arrows on each row. Suggest print order (white last as highlight) puts the underbase first, then colors from light to dark, black next to last, and white on top as the highlight white. The order prints on the ticket and in each film label.

Trapping between inks. Spread (+) or choke (-) moves one ink's edge from -3 to +3 mm in 0.05 mm steps, so a lighter ink can tuck under a darker neighbor. Apply to all inks spreads every ink except the darkest by the Default trap, 0.15 mm unless you change it; the helper notes a typical 0.1 to 0.35 mm.

Print size from the file. Underbase reads the resolution tag of PNG and TIFF files and rasterises SVG, PDF, and Illustrator (.ai) files at 300 dpi at their true size. Set Print width in inches or, with Show sizes in millimetres on, in millimeters; the height follows the artwork.

Generate. Choose Generate underbase pack, or press Ctrl+G, and the film PDF, 1-bit TIFFs, unscreened channels, ticket, preview, and job file are written to one folder named for the job. Save the job with Ctrl+S to reopen it for the reorder.

How it is built

Built for the press, not the design studio.

The press sets the limits

You enter the screens your press holds, the mesh, and the dot gain you measure. Underbase counts every plate against that budget and thins halftones to match before any film is written.

Film at true size

Every plate lands on the sheet at true size with identical registration marks, center ticks, and a label naming the job, plate, ink, screening, offset, and mesh.

Nothing uploads

Underbase runs entirely on your PC with no account, no telemetry, and no network connections. Customer artwork is only read. One-time purchase in the Microsoft Store.

FAQ

Straight answers—no glossary dump

How does Underbase decide which colors are inks?

In spot mode it gathers the colors in the artwork, groups close shades into one ink, and assigns anti-aliased edge pixels to the inks on either side, so a smooth curve does not become extra plates. A color that fills the image border is treated as the background and set not to print. You see every ink with its coverage and can change any of it before generating.

Can I rename, merge, and reorder the inks?

Yes. Select an ink to type a new name or pick a stock name such as Kelly Green or Highlight White, and set its hex color. Merge this ink into folds it into another ink. The arrows on each row move it earlier or later in the print order, and the Print toggle switches an ink off when it is really the garment. Reduce to merges down to a target count.

What print order does Underbase suggest?

Suggest print order (white last as highlight) puts the underbase first, then the colors from light to dark, with black next to last and the white ink on top as the highlight white over the choked underbase. You can still move any ink with the arrows on its row, and the final order is written on the production ticket and on every film label.

What artwork files does Underbase open?

PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF, and Illustrator (.ai) files, opened with Open artwork, by dropping the file on the window, or from Samples. Vector files are rasterised at 300 dpi at their true size. A raster file's resolution tag sets the print size; when a file has no tag, Underbase uses 300 dpi, flags it, and lets you edit the source resolution or type the print width you want.

Does my customer's artwork stay on my PC?

Yes. Underbase runs entirely on your PC. There is no account, no upload, and no telemetry, and the app makes no network connections. It reads the artwork you open, writes each job to a folder inside the output folder you choose, and keeps its own settings in local app data. Jobs save as .underbase files you can reopen for a repeat order.

How do I get Underbase, and is there a trial?

Underbase is a one-time purchase in the Microsoft Store, and the listing shows the current price in your currency. The Store runs a 15-day free trial, so you can separate a job you have already printed, or one of the six bundled samples, and compare the film with what you burned. The Store installs and updates the app. It runs on Windows 11 version 24H2 or later on x64 PCs.

Related pages

A white underbase for dark shirts, choked so it stays hidden. From customer art to film, in one separation app. Gradients and soft shadows, printed with a handful of inks.

Customer art in.
Press-ready film out.

Underbase separates flat and shaded art into spot inks, builds a choked white underbase, traps colors in one click, keeps the job inside your plate budget, and writes true-size film with registration marks and a production ticket. Everything runs on your PC, and the Microsoft Store runs a 15-day free trial.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Open full product page

Illustrator is a trademark of its owner, registered in the U.S. and other countries. Underbase opens Illustrator (.ai) files as an input format and is not affiliated with or endorsed by the trademark owner.

Technical specifications

Technical specifications for procurement

Spec Implementation
Data Sovereignty Reads only the artwork you open or drop on the window and never writes to it; writes each job (film PDF, TIFF plates, channels, ticket, preview, and .underbase job file) to a folder inside the output folder you choose; settings stay in local app data on this PC
Telemetry Status None; no account, no upload, no telemetry, and no network code in the app
Core Runtime .NET 10 and WPF, self-contained, distributed through the Microsoft Store as an MSIX package; separation, halftoning, TIFF, and PDF output run in the app’s own engine, with PDF and Illustrator (.ai) pages rendered by a bundled PDFium engine
Network Requirements Fully functional offline; the app makes no network connections and nothing is uploaded
Deployment Compatibility Windows 11 version 24H2 or later (10.0.26100), x64; 8 GB RAM recommended for very large artwork, about 400 MB of disk; one-time purchase in the Microsoft Store with a 15-day free trial
Inputs PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF, and Illustrator (.ai) files; vectors rasterised at 300 dpi at true size; print size from the file’s resolution tag or a print width you set, in inches or millimeters
Separation Spot mode (one ink per flat color, close shades grouped, background left unprinted) or index mode (error-diffusion dither between a fitted ink set, dither strength 0 to 100); reduce to 1 to 16 inks; rename, merge, reorder, or switch off any ink
Underbase and traps White underbase from the inks you choose, choke 0 to 3 mm; spread or choke per ink from -3 to +3 mm; one-click trapping of every ink under the darkest; suggested print order with highlight white
Screening Solid or halftone per plate at 10 to 120 lpi, any angle, with tint; ruling suggested from mesh count; dot-gain compensation from 0 to 50 percent; output dots preview at the output resolution
Outputs True-size film PDF with registration marks, center ticks, and plate labels, one plate per sheet or ganged, mirror for emulsion down; 1-bit CCITT G4 film TIFF per plate at 600, 720, 1200, or 1440 dpi; unscreened 8-bit channel TIFFs; production ticket as PDF and JSON; preview PNG; .underbase job file
Film sizes Letter, Legal, Tabloid, Super B, ANSI C, A4, A3, A3+, A2, or a custom sheet up to 60 x 120 in; direct printing to any Windows printer