Trichromatic film scanning · 665 / 525 / 455 nm

The Frontier SP‑3000 look.
From your own camera.

Develop your colour negatives — no scanner needed. Three narrowband exposures in, a finished scan out, through the same kind of pipeline a real film lab's SP‑3000 and Pakon F‑135 run — stage by stage.

Not a filter, and not a model of one. One measurement per roll, then a whole roll that agrees with itself.

New to this? What three narrow bands change →

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Free for 7 days and 15 rolls, no account · macOS 14+ & Windows 10 22H2+

A woman on a vaporetto looking back through the window, the Venice lagoon and the far shore beyond her, reflections lying across the glass — a colour negative developed by Trichroma Lab.
Three black-and-white separations, screened back together. That is not a treatment applied to a photograph — it is how the photograph is made.

What goes in

The negative, and the photograph in it.

Three exposures go in, one through each narrow band. Together they are the colour negative — orange mask and all. Right is what Trichroma Lab made of it: the same frame, nothing else changed.

The chart is not there to look technical. This is one of the frames the colour transform was worked out on. A chart on film, scanned on a Frontier SP‑500, is how that scanner's colour stages were recovered — its own raw in, its own finished scan out; flat patches spanning the gamut are the only thing that pins a transform down. And a chart is the only thing in a picture that can settle whether a colour landed where it should. A face can only look plausible.

The same frame through the 665 nm band alone: one exposure, red, the chart's patches reading as densities rather than colours.

665 nm

The same frame through the 525 nm band alone: one exposure, green, the chart's patches reading as densities rather than colours.

525 nm

The same frame through the 455 nm band alone: one exposure, blue, the chart's patches reading as densities rather than colours.

455 nm

The three exposures combined into one colour negative: the orange mask over the whole frame, the subject holding a colour chart, tones reversed.

The negative

The same frame developed by Trichroma Lab: the mask removed and the colour resolved, the chart's patches reading as themselves.

Trichroma Lab

Against a lab scan

The same frame: a Frontier SP‑3000, and a camera on a copy stand.

Six negatives, six emulsions — each pair cropped to the same frame and both with the rebate left off, because a border on one side alone is a tell and a light surround shifts how you read the colour inside it.

A portrait on Opticolor 200, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Opticolor 200 Narrowband RGB · 665 · 525 · 455 nm

A white timber house behind a railing thick with climbing greenery, on Lomo 400, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Lomo 400 Narrowband RGB · 665 · 525 · 455 nm

A woman in sunglasses on a city street, a pedestrian crossing sign behind her, on Portra 400, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Portra 400 Narrowband RGB · 665 · 525 · 455 nm

A woman under red and yellow light, head tilted back, on Portra 800, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Portra 800 Narrowband RGB · 665 · 525 · 455 nm

A woman with a shopping trolley waiting at a pedestrian crossing, a tabac behind her, on Kodak Vision3 50D, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Vision3 50D Narrowband RGB · 665 · 525 · 455 nm

A small child standing on a café chair beside a window, on Kodak Ultramax 400, scanned on a Fuji Frontier.
Frontier SP-3000
The same negative, developed by Trichroma Lab from three narrowband exposures.
Trichroma Lab

Ultramax 400 Narrowband RGB · 665 · 525 · 455 nm

Both halves of every pair came off this page — same negative, same crop, same compression. Six frames; not a claim about every roll ever shot.

  • A town of white houses on a cliff above the sea at dusk, the first lights reflected in calm water. Kodak Gold 200
  • A sunlit harbour quay with sacks of netting and a red stall sign reading ŚWIEŻE RYBY, fishing boats behind. Kodak Portra 160
  • A woman lying in grass among dandelions and daisies, shading her eyes from the sun, in a mustard shirt and jeans. Kodak Portra 160
  • A café on stilts over a green pond, a blue-and-white umbrella on its terrace and tall trees overhead. Kodak Vision3 250D
  • A black-and-white cow with yellow ear tags looking straight at the camera through tall grass. Kodak Portra 800

More frames, developed in Trichroma Lab and shown on their own, with no lab scan beside them.

Show more

Where the look comes from

Not a preset. A pipeline — and it is measured.

A lab scanner does not lay a look over a scan. It measures the negative and computes one, in fixed stages, and the Frontier SP‑3000 and its smaller sibling the SP‑500 compute the same one. Trichroma Lab is an independent implementation of a pipeline of that kind, written in Dart: it measures your film base first and computes from there. Nothing in it is a curve drawn by eye.

A second pipeline ships beside it. The Pakon F‑135 computes a different look from the same densities, and Trichroma Lab is an independent implementation of that one too — on 35 mm and on 120.

Every stage is pinned by generated parity vectors that run on every build. The integer stages are compared exactly — a difference of one is a difference in the rule. The floating-point stages have to agree to within 1e‑9. That is what keeps a build from drifting.

Whether it lands where a lab lands is not something to take on trust. Six negatives above, each developed twice, with every number read off the two files on this page.

Trichroma Lab prescanning a roll: frame 20 of 37, film base measured at 0.383 D red, 0.814 D green and 0.957 D blue, with cross-sections and a surface plot of the light, and the registration between the separations at 1.42 px median.
Every roll starts by measuring its own film base, in density, per channel — and the registration between the three separations, in pixels.

The console

The lab's vocabulary, on a screen built for it.

Density leads, then cyan, magenta and yellow — subtractive naming, because that is how the correction works: +C removes red. Anyone who has had lab scans done already reads this language.

The FRONTIER screen: frame 10 of 13 on a graph-paper canvas, scopes and the four correction axes on the right, the roll's measured film base and its rig on the left, and the filmstrip along the bottom carrying every frame's D/C/M/Y.
Scopes read the render and the sensor separately. Tone Adjustment offers seven named looks as live thumbnails of the frame you are on — you pick a look, not a curve. Hold BEFORE to drop back to neutral.
The MERGE screen in Trichroma Lab: forty-two raw files grouped into fourteen frames, with one frame's three separations — red, green and blue — shown beside it on the right.

The method

Three exposures, three narrow bands.

A colour negative's dyes are cyan, magenta and yellow. Photograph it under white light and you measure those dyes through your sensor's own filters, which overlap — the channels contaminate each other, and the orange mask has to be guessed away afterwards.

Shoot it three times instead, once under each narrow band, and every exposure measures one dye layer and almost nothing else. That is what a minilab does, and it is why the numbers coming out of it are worth a pipeline this exact.

How trichrome scanning works →

What it works out by itself

The parts you should never have to do twice.

Which three are one frame

Read from filenames, capture time, shot order — and from the image itself, because a red-filtered negative measures nothing like a blue one.

Sub-pixel registration

The three separations are laid over each other to a quarter of a pixel, resampled rather than nudged to the nearest one. Every roll reports how far each channel had drifted.

Film base density

Measured off the clear rebate around each frame, per roll, in density — not picked off a border by eye.

Where the film sits

Mark the holder once. It is saved with the rig, so every roll you shoot on that setup arrives already set.

Crop and straighten

One pass per frame. Frames the detector will not commit to are left whole, and the app says so.

Faces and scene contrast

Found on a small positive, four rotations deep, because a film frame's orientation is unknown. Contrast is measured during the roll pass — a reading, not a switch.

Read this before you buy

One rig so far — but two lamps on it.

Every frame here was shot on the one station this is calibrated for: a Scanlight v4 at 665, 525 and 455 nm, the light the app names Narrowband RGB. Under those three bands it never asks what film you shot — the base is read off your own rebate. The same station also takes one white-light exposure instead of three, but its channels arrive already mixed by the camera's filters, so there you name the emulsion from a table of twenty. Against three bands, over a roll, that costs about five counts a channel.

That unmixing was fitted here and the camera is half of it, so on another body or another lamp the colour lands somewhere else — and I cannot tell you where until I have seen it. If you have a rig, write to me or post it on Discord: we work out its calibration together and it ships in the next build.

Tell me about your rig

The light calibration sheet: three wells, one for each of the 665, 525 and 455 nanometre exposures of the empty gate.
Three shots of the empty gate, one under each diode — the narrowband lamp's sheet. The white lamp has its own, and one shot fills it. Without a flat a density has no denominator, so the app asks, and lets you continue without one only if you say so out loud.

Questions

The things worth asking first.

What do I actually have to shoot?
Three exposures of every negative — one under a red band, one green, one blue — plus three shots of the empty gate once per session. Import them in any order; the app works out which three belong together. There is also a one-shot white-light mode for when you have no RGB lamp: one exposure per negative, one flat, and you name the film — which the three-band path never asks you to do.
Does it work with my camera?
It reads NEF, NRW, CR2, CR3, ARW, DNG, RAF, ORF, RW2 and PEF, plus TIFF if you have already-developed scans. Under the three bands there are no per-camera profiles to pick, because the bands are what defines the measurement, not the sensor's own filters. Under white light it is the other way round — the sensor's filters are half the instrument there, which is why that mode is calibrated for a named station rather than offered blind.
Do I need Lightroom?
No. Trichroma Lab is a standalone application for macOS and Windows, and the raws you import are never moved or changed. A roll is a single .trichroma file that keeps its own copy of the sensor data it needs — not your raw files — so it opens, re-renders and exports without them; keep the raws as your archive. What you export is yours, in open formats: a TIFF, a JPEG, or the negative itself as a linear 16-bit TIFF for another converter.
My light source is not the one you built this on.
It depends which way it differs. A white lamp is a mode the app already has, measured on the one station this was built on. Bands at other wavelengths, or the same lamp on a different camera, change the measurement itself — the app will still develop the roll, but the colour will not land where these frames landed, and I cannot tell you in advance where it will. Get in touch and we will measure yours.
What does it cost?
Two plans: Personal for your own rolls — monthly, yearly or once — and Pro, by the month or the year, which adds the 16-bit colour chain, the graphics-card preview, background runs and FRONTIER PRO. Every plan starts with a free trial of 7 days and 15 rolls, with no account. Prices and the full comparison are on /pricing.
Is my film stock supported?
Twenty stocks have a measured base in the app. Under the three bands you are never asked which one you shot — the base is read off your own rebate on every roll, so an unlisted stock is not a wall. Under white light you do name it, because a single exposure cannot measure that base itself; your roll's own base then tunes the table entry to your development batch.

Get started

Try it on your own film.

Download the app and start the trial from inside it: 7 days and 15 rolls, with everything on, no account and no card. Then pick a plan.

  • Personal · $7.99 / month · $59 / year · $249 once
  • Pro · $14.99 / month · $119 / year
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macOS 14+, universal · Windows 10 22H2+, x64