Free
€0
With an account, no credit card
- The full workflow: target, curve, negative
- 3 saved curves, unlimited presets
- 10 HD scans, unlimited generated images
- 300 MB synced across web, iPhone and iPad
- Color Venn CMYK
Calibration · Negatives · Colour separation
Calibrate your alternative prints.From file to negative, in one app.
Print the target, expose it with your process, photograph the result: Calibration Flow computes the curve that puts every grey back in its place. Then it makes your negatives, in black and white or separated into colours.
Cyanotype · gum bichromate · platinum-palladium · Van Dyke · carbon · screen printing
No credit card · in the browser, on iPhone and on iPad
Designed and reviewed by Tristan Sidem and Raphaël Lebas de Lacour, co-founders of Vision Picturale
Where do you want to start?
- CalibrateMy prints lack tonal rangeBlown highlights, blocked shadows: your process curve corrects them.
- ColourI want to print in colourOne image, four to seven plates, and the simulated print before you expose.
- StartI’m new to alternative processesA kit designed for the app, and a step-by-step manual for your first curve.
Calibration
A curve that makes your process linear.
Every process responds in its own way: it crushes the highlights, blocks the shadows. The app measures how yours responds on a 25-patch target, then computes the curve that compensates for it. Your print gets back every value in your file.
In three moves
- 01
Print the target
The app provides it: 25 patches, printed on film like a negative.
- 02
Expose it, then photograph it
With your usual process, then your phone. No densitometer, no spreadsheet.
- 03
Apply the curve
Straight onto your negative in the app, or exported as .acv (Pro mode) for your editing software.
Negatives and colour
A negative ready to expose. In black, or in colour.
The curve applies straight to your image. Set the format, the halftone, the mirroring, and get a high-definition negative ready to print on film. In colour, the app separates your image into plates and shows you the simulated print before the first coat.
- CMYK four-colour: one plate per pass.
- Full Gamut: up to seven inks, adding orange, green and violet.Pro
- The simulated print, to judge the colours before you brush on the first coat.
- The hue sphere, to tune each ink by eye.
All-in-one
One app instead of six.
Alternative printers usually equip their workshop piece by piece: a densitometer, a spreadsheet, a curve generator, separation software, a timer, a calculator. Here everything speaks the same language and follows you from one device to the next.
- DensitometerYour phone camera reads the 25 patches as L* luminance.
- Measurement spreadsheetThe curve computes itself, smoothed and without reversals. No formula to write.
- Curve generator.acv export (Pro mode) for your software, plus reference curves per process to get started.
- Separation softwareCMYK plates up to seven inks, and the simulated print.
- Exposure timerA built-in timer that drives the Luminograph over Bluetooth.
- Exposure calculatorAn estimate of your exposure time before the first test.
And also
Pricing
Free to start. Pro when your practice grows.
Pro
€9.90/ month
Or €99/year, i.e. 2 months free · no commitment · one subscription for web and iOS
- .acv export for Photoshop, Lightroom and other editors
- Unlimited curves
- 5 GB of storage
- Full Gamut: HD export of 5 to 7 inks
- Advanced separation settings, CMYK tonal separation
- Reference curves, advanced export options
You upgrade to Pro from inside the app, the day you need it.
A Luminograph bought from Vision Picturale includes one year of Pro.
Full pricingGetting started
Kits designed for the app.
Every Vision Picturale kit explains how to calibrate its process with Calibration Flow. You start from a reliable base, not a failed print.
Frequently asked questions
Everything about Calibration Flow.
- Calibration Flow is a precision tool for calibrating alternative photographic printing processes (cyanotype, platinum, Aquaprint, carbon, etc.). It measures patch luminance L* CIELAB via smartphone camera on 25 patches (no densitometer, no spectrophotometer, no Excel), linearises with robust LOWESS + monotonic PCHIP, down to the correction curve. Free tier with account registration (full workflow including Color Venn CMYK, 300 MB cloud sync), Pro subscription 9.90 EUR/month for .acv preset export (Photoshop / Lightroom Classic), unlimited curves, 5 GB of storage and advanced features (Full Gamut HD export of 5 to 7 inks, advanced separation settings, advanced export options). 1 year of Pro included with a Luminograph purchase from Vision Picturale.
- Calibration Flow supports six alternative printing processes with a dedicated preset: Cyanotype, Aquaprint (gum bichromate), Platinum-Palladium, Van Dyke, Carbon, and Screen printing — each with its own target, polarity and settings. Three tangent processes, with no dedicated preset — Bromoil, Gumoil and Resinotype — still calibrate with the same 25-patch target: the app measures a result, not a method. It remains a generic tool: beyond this list, it can also calibrate a custom process, or even the digital printer itself, as long as it involves a measurable UV exposure in grayscale. Patch measurement always happens via smartphone camera, with no densitometer or spectrophotometer required, using the same robust LOWESS + monotonic PCHIP linearisation algorithm across every process. A first calibration takes about 15 minutes and stays valid for months as long as the chemistry batch and UV source remain unchanged.
- The Free tier is fully usable with a free account on picturale.app — full workflow, 3 saved curves, Color Venn CMYK preview for quadricolour gum/carbon, 300 MB of synchronized cloud storage. The Pro subscription at 9.90 EUR/month (unified web and iOS) unlocks unlimited curves, 5 GB of storage, Full Gamut HD export of 5 to 7 inks, and advanced export options. A Luminograph purchase from Vision Picturale includes 1 year of Pro.
- No, no dedicated measuring equipment is required. Calibration Flow replaces the densitometer, spectrophotometer and spreadsheet traditionally used in alt-process work: all you need is a smartphone (native iOS app via Capacitor, or simply a web browser) with a camera. The app itself provides the calibration target to print — 25 patches, negative for most processes — which you expose and develop using your usual process. Once the print is dry, you photograph it with your phone: the app reads each patch in relative intra-target mode, without needing calibrated lighting or a dedicated darkroom setup. All you need beyond that is your existing printing setup (developing tray, UV source, paper, chemistry). If you use a Vision Picturale Luminograph exposure unit, its UV timer can even be controlled over Bluetooth directly from the app, with automatic LED cut-off.
- Calibration Flow is developed within the Picturale ecosystem by Tristan Sidem (founder of Calibration Flow + Vision Picturale, 8 years of cyanotype practice) and Raphaël Lebas de Lacour (co-founder of Vision Picturale). The site's technical content follows a strict editorial rule: every process page is signed "Article reviewed by" both founders with its technical references (Christopher James, Bostick & Sullivan, Mark Nelson), and every manual page carries a "Verified" date marking the last time the content was checked against the app's actual behavior. The app remains a calibration tool: chemistry kits are sold by Vision Picturale.
Your first curve starts here.
Create your free account and start calibrating in the browser, or install the app on iPhone and iPad. One account, the same curves everywhere.
Create my free accountDownload on the App Store
No credit card · in the browser, on iPhone and on iPad