01
The printer
Model, ink set, driver. An Epson SC-P700 and a Canon PIXMA do not lay down the same ink density per numerical value — the same source image produces two different negatives, hence two different correction curves.
Tool · .acv curve library
Reference .acv curves — Luminograph + VP processes.
An open library of curves calibrated on Vision Picturale processes exposed with the Luminograph A4 or A3+. Each curve is defined by three canonical variables: the printer used, the print settings, and the exposure time under the Luminograph. Downloads are coming — for now, the tool shows you the promise and gives you the method to build your own.
What defines an .acv curve
Three variables that change everything.
Contrary to a common belief, the printing paper is not the main variable. What determines your curve is the chain upstream of the print: what comes out of your printer onto the transparency, and how long you expose that transparency.
02
The print settings
Media type chosen in the driver, photo quality, DPI, colour management off (an absolute rule, see the manual). Changing a single one of these settings shifts the final curve.
03
The exposure time
Precise duration under Luminograph A4 or A3+. At equivalent chemistry and paper, ±30 seconds shift the tonal range. For this reason, each curve in the library cites a reference time — that is your anchor point.
Paper plays a role of course — its grain, its chemical neutrality, its reactivity to the sensitiser. But on a stable Vision Picturale chain (VP N°03 sensitiser, 640 g/m² cotton paper), the major steps come from the three variables above. Manual detail on printing without colour management.
Library being built
Vision Picturale processes × Luminograph.
A scope deliberately restricted to VP processes exposed with the Luminograph A4 or A3+ — the combination on which Calibration Flow can publish reliable curves, because chemistry and UV source are controlled. The curves below are planned entries — none is yet available for download.
- Soon
Luminograph A4
Cyanotype
- Printer
- Epson SC-P700
- Settings
- Inkjet transparency, photo quality, colour management off
- Exposure
- 8 min
- Soon
Luminograph A4
Gum bichromate (Aquaprint Monochrome)
- Printer
- Epson SC-P700
- Settings
- Inkjet transparency, photo quality, colour management off
- Exposure
- 3 min per layer
- Soon
Luminograph A3+
Aquaprint CMYK Quadricolour
- Printer
- Epson SC-P900
- Settings
- Inkjet transparency A3, photo quality, colour management off
- Exposure
- 3 min per layer
- Soon
Luminograph A4
Carbon Museum Black
- Printer
- Epson SC-P700
- Settings
- Inkjet transparency, photo quality, colour management off
- Exposure
- 4 min
- Soon
Luminograph A3+
Carbon Deep Colour (CMY trichrome)
- Printer
- Epson SC-P900
- Settings
- Inkjet transparency A3, photo quality, colour management off
- Exposure
- 4 min per layer
- Soon
Luminograph A4
Bromoil
- Printer
- Epson SC-P700
- Settings
- Inkjet transparency, photo quality, colour management off
- Exposure
- 2 min
- Soon
Luminograph A4
Gumoil
- Printer
- Epson SC-P700
- Settings
- Inkjet transparency, photo quality, colour management off
- Exposure
- 4 min
- Soon
Luminograph A3+
Resinotype (positive target)
- Printer
- Epson SC-P900
- Settings
- Inkjet transparency A3, photo quality, colour management off
- Exposure
- 5 min
Downloads will open progressively, curve by curve, as soon as a combination has been calibrated and validated at the workshop on two distinct prints (reproducibility test). We prefer to release nothing that has not been verified.
Démonstration · 3 sliders, une courbe corrective
Ajuste la courbe en direct
Calibration Flow corrige n'importe quelle réponse non-linéaire avec trois sliders. Pas de point à dessiner à la souris, pas de Bézier à manipuler. Joue avec les valeurs ci-dessous et vois immédiatement l'effet sur la courbe et sur le rendu tonal your process.
Entrée 0–255 ↔ Sortie 0–255
Seuil d'entrée minimum. Tout ce qui est en dessous devient noir pur.
Seuil d'entrée maximum. Tout ce qui est au-dessus devient blanc pur.
Courbure des tons moyens. 1,00 = linéaire, < 1 = mid-tones sombres, > 1 = mid-tones clairs.
Dégradé source (avant correction)
Dégradé corrigé (après application de la courbe)
Cette démo applique une formule simple (points noir/blanc + exposant gamma) pour l'illustration. L'app utilise en plus un lissage par LOWESS robuste + PCHIP monotone qui arrondit les transitions sans créer d'artefacts. Tu exportes ensuite un fichier .acv chargeable dans Photoshop ou Affinity Photo en deux clics.
What really matters
Build your own curve database.
The best curve for you is the one that comes from your printer, your settings and your exposure time, at home, in your workshop, with your production flow. No external library will ever replace that.
Calibration Flow is built so you progressively assemble your own library, curve by curve. Each calibration is saved as a preset with its metadata — process, printer, settings, UV source, exposure time, date. Over six months of practice, you get a dozen reliable presets you recall in two clicks before each print. That is your real reference base — and it follows you across your devices via the iOS subscription cross-device sync.
Step 1
Calibrate
Print the 25-patch test chart, expose, scan. Calibration Flow computes the correction curve and exports it as .acv.
Step 2
Document
The app automatically saves the context: process, printer, settings, UV source, exposure time, test date.
Step 3
Reuse
On your next print of the same type, open the preset, apply the curve. If the chemistry has drifted slightly, recalibrate — the app keeps the history to compare.
Free with sign-up on Web, no credit card.
Why this scope
Luminograph + Vision Picturale processes only — here is why.
To publish a curve useful to a third-party practitioner, the three canonical variables must be controlled enough for the curve to transpose. The Luminograph provides that stability: known UV irradiance, second-precise duration, fixed exposure geometry. A curve calibrated under a Luminograph A4 here stays usable for you with a Luminograph A4, provided your printer and settings are close.
For Vision Picturale processes, the chemistry is standardised (VP N°03 Universal Sensitiser, VP N°05 pigmented gelatins, etc.). A curve calibrated on VP chemistry stays reproducible for other practitioners using the same chemistry. Outside the VP range, home chemistries vary too much from one practitioner to the next — publishing a generic curve would be dishonest.
If you work in natural light, under UV tubes or with a chemistry outside VP, Calibration Flow works just as well — but you build your own private library, because no external curve will fit your configuration.
Usage
How to use an .acv file?
The .acv format is Photoshop’s native Adobe Curves File, dating from its earliest versions (1991). It stores up to 16 curve points (version 1). Photoshop and Affinity Photo import it directly via their Curves panel (non-destructive adjustment layer). Lightroom does not read it natively — see the dedicated workflow.
Your own curve, exportable as .acv.
Free with sign-up on Web, no credit card. 25-patch test chart, L* reading, .acv export compatible with Photoshop & Affinity. Local preset library + cross-device sync with the iOS subscription.