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 chemistry. But on a stable Vision Picturale chain (standardised Aquaprint chemistry, VP N°03 Developer, 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 Mono)
- 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
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.
Demo · 3 sliders, one corrective curve
Adjust the curve live
Calibration Flow corrects any non-linear response with three sliders. No point to draw with the mouse, no Bézier handle to wrangle. Play with the values below and see the effect on the curve and on the your process tonal rendering immediately.
Input 0–255 ↔ Output 0–255
Minimum input threshold. Everything below it becomes pure black.
Maximum input threshold. Everything above it becomes pure white.
Midtone curvature. 1.00 = linear, < 1 = darker mid-tones, > 1 = lighter mid-tones.
Source gradient (before correction)
Corrected gradient (after applying the curve)
This demo applies a simple formula (black/white points + gamma exponent) for illustration. The app additionally uses a robust LOWESS + monotone PCHIP smoothing pass that rounds off transitions without creating artefacts. The Mode Pro (€9.90/month) then lets you export a .acv file, loadable into Photoshop or Affinity Photo in two clicks.
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 (Pro mode).
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 (pre-dosed Aquaprint pouches, VP N°03 Developer, VP N°04 Universal Primer, 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, corrective curve. .acv export compatible with Photoshop & Affinity in Pro mode. Local preset library + cross-device sync with the iOS subscription.