Comparison · Alt-process calibration tools
QuadToneRIP vs Calibration Flow — which tool for your alternative process?
Cyanotype, gum bichromate, platinum/palladium, carbon: each process has its constraints. Here is a factual comparison of five approaches — including those where Calibration Flow is not the best choice.
Comparison table
Five tools, seven criteria.
Free QuadToneRIP alternative, PiezoDN comparison, Easy Digital Negatives comparison, best alt-process calibration tool — comparison without marketing filter.
| Criterion | Calibration Flow | QuadToneRIP | PiezoDN | Easy Digital Negatives | Manual densitometer |
|---|---|---|---|---|---|
| Hardware required | Smartphone (camera) + Web or iOS. No densitometer. | Dedicated printer (K7/piezo inks) + Mac/Windows + printer-specific driver | Epson piezo printer + Piezography inks + Mac/Windows + spectrophotometer recommended | Windows PC + Photoshop + standard inkjet printer | Densitometer or spectrophotometer (€200–2,000) + external curve software |
| Learning curve | Low — target, photo, .acv export, apply in Photoshop/Lightroom Classic | High — print profiles, .quad curves, low-level RIP driver | Very high — closed Piezography chain, densitometric measurements, linearisation | Moderate — guided interface but Windows-specific | Variable — robust method but no automation; manual value entry |
| Entry price | €0 (free account, 100 MB) · Pro €9.90/month · Luminograph 1 year included | ~$50 licence + dedicated-printer cost (variable) | Piezography inks + Piezography Pro software (several hundred dollars) | ~$50–100 depending on licence | Densitometer cost (€200–2,000) + manual curve |
| Mobile (smartphone) | Yes — native iOS + Web; the smartphone camera replaces the densitometer | No | No | No | No (manual entry) |
| Curve output | Export .acv (Photoshop, Lightroom Classic) | .quad curves injected directly into the print RIP | Piezography profiles (curves internal to the closed chain) | Photoshop curves (internal proprietary format) | Raw data — curve to build manually in Photoshop or Lightroom |
| Multi-channel / colour | Yes — native CMYK multi-channel calibration (polychrome gum, Aquaprint, colour carbon) | Mostly monochrome (K7); limited multi-ink | Monochrome (optimised for black-and-white piezo negatives) | Single-channel by default | Possible channel by channel but entirely manual |
| Calibration cycle | Short — photo of target → automatic analysis → curve in minutes | Long — printing, measurements, iterations on .quad profiles | Long — spectrophotometric measurements + linearisation | Moderate — guided but several round-trips | Long — each measurement entered by hand |
Honesty first
When to choose another tool?
QuadToneRIP stays unbeatable for a dedicated K7 printer
If you drive a monochrome K7-ink printer (seven shades of black, e.g. a converted Epson 3880), QuadToneRIP is the reference. It controls ink injection channel by channel via a low-level RIP driver — a precision that Calibration Flow, which operates on the silver-negative side, does not address. If your workflow centres on direct monochrome digital printing with dedicated piezo inks, QuadToneRIP vs Calibration Flow is not really a comparison: they are two different problems.
PiezoDN for a closed pigment chain at maximum precision
PiezoDN is designed for the full Piezography chain — inks, profiles, Epson printer, spectrophotometric measurements. If you work exclusively in that ecosystem and seek absolute densitometric precision without compromise, PiezoDN is built for it. The investment in hardware and learning time is real, but the reproducibility on platinum/palladium negatives can reach levels hard to match otherwise.
The manual method (densitometer) if you already master the tool
A practitioner who already owns a lab densitometer or spectrophotometer and has built their manual method does not necessarily need to switch. The measured values are objective, exportable, and independent of a subscription. The only drawback is entry time and the lack of multi-channel automation.
Positioning
Who is Calibration Flow the right choice for?
Calibration Flow stands out on four axes the tools above do not address head-on:
- Short cycle, no specialised hardware. You photograph your target with your smartphone, the app analyses it and generates the curve. No densitometer, no RIP driver, no printer configuration.
- Mobile-native. The iOS app uses the camera as a density sensor. It is a direct alternative to the densitometer for processes where L* measurement can be done under constant lighting — cyanotype, gum bichromate, Van Dyke, carbon.
- .acv export, mainstream software. The exported curve is a standard
.acvfile, readable in Photoshop and Lightroom Classic. No third-party software, no closed proprietary format. - Native multi-channel colour. For colour pigment processes (polychrome gum, CMYK Aquaprint, colour carbon), Calibration Flow handles channel-by-channel calibration — a structural gap of QuadToneRIP and PiezoDN on this specific use case.
In short: if you work with a standard desktop printer and mainstream software (Photoshop, Lightroom Classic), and you want to calibrate without extra hardware investment — especially on colour processes — Calibration Flow is the shortest path to a reproducible curve.
Going further
Calibration resources
- Cyanotype calibration with Calibration Flow — step-by-step guide, 21-step target,
.acvexport - Manual · 25-point polynomial curve — how the algorithm builds your correction curve
- Gum bichromate calibration
- Platinum/palladium calibration
- Carbon calibration
Get started
Try Calibration Flow — free account, no credit card.
Free account: 100 MB, all the basic features. Pro at €9.90/month for the 25-patch target, the .acv export, multi-channel calibration and the Luminograph code.