A calibration curve only has value if you can apply it to your images. Calibration Flow doesn't handle the final print — it generates the correction you're going to apply in your usual printing workflow. The bridge between the app and Photoshop is the

.acv

file.

The

.acv

is a proprietary Adobe format that has existed since 1991. Photoshop reads it natively, any recent version, without a plugin. You generate your file in Calibration Flow, you load it into Photoshop, your curve is applied to your image. It's the simplest possible interoperability — no conversion, no adaptation, just a file that passes from one app to another.

#What you do

Once your curve is generated in Calibration Flow, you click "Export curve

.acv

". A dialog box asks you where to save the file. You choose a descriptive name — typically something like

cyanotype-arches-vp03-mai2026.acv

— and you confirm. The file lands in your downloads folder (or the location you chose).

The file is under one kilobyte. It's a compact binary format that contains only the points of your curve and their input and output position. It doesn't contain the image, the target, or the process metadata — just the mathematical correction function.

To use it in Photoshop:

Open in Photoshop the image you want to correct (the final image intended for the print, not the calibration target).
Create a Curves adjustment layer: Layer menu → New Adjustment Layer → Curves, or shortcut
```
Cmd+M
```
(Mac) /
```
Ctrl+M
```
(PC).
In the Curves palette that opens, click the menu icon at the top right (the three horizontal lines or the gear icon depending on your Photoshop version).
Choose "Load preset" or the equivalent in your language.
Navigate to your
```
.acv
```
file, select it, confirm.

The curve is instantly applied to your image. You see the result in the Photoshop preview. You can always adjust the points individually in Photoshop if you want to fine-tune — the adjustment layer stays editable.

#Why it matters

For separation of work. You calibrate in Calibration Flow (with your target, your process, your paper), you apply the calibration in Photoshop (with your images, your usual workflow). Each tool does what it does best, and the

.acv

is the clean boundary between the two.

For non-destructive work. A Photoshop adjustment layer never alters your source image. You can disable the layer, change its parameters, move it in the layer stack. If your calibration changes later, you replace the

.acv

in the layer and the whole document updates.

For portability. The

.acv

is a standard format for three decades. If you switch calibration tools in two years, your

.acv

archives stay readable by Photoshop. You don't depend on Calibration Flow to replay an old calibration — you just need the curves and Photoshop.

#When it's not enough

If you don't have Photoshop. The

.acv

is read natively by Photoshop. Other tools (GIMP, Affinity Photo, Krita, Capture One) don't read it. See the Lightroom export page for alternative workflows.

If you want to apply the correction to hundreds of images in batch. Photoshop can do it via Actions, but it's heavy. For series production, look at batch processing tools (Adobe Bridge, ImageMagick with a script that applies a LUT).

If you want to export the curve to store it as metadata of a more complex workflow. The

.acv

is a minimalist format, not a rich description. For complete documentation (process, paper, date, source target), stay in the Calibration Flow presets library.

#Worth remembering

Element	Value
Format	`.acv` Adobe (compact binary)
Typical size	Under one kilobyte
Compatibility	Photoshop CS6+ and all recent versions
Number of points	Up to 16 (limit of the format)
Workflow	Curves adjustment layer → Load preset
Non-destructive	The layer preserves the source image
Editable	You can adjust the individual points in Photoshop

#The test

Export a curve from Calibration Flow to an

.acv

. Check that the file is under one kilobyte (otherwise something went wrong). Open Photoshop, create a new blank document, add a Curves adjustment layer, load your

.acv

. The curve should appear in the Curves palette with its characteristic shape. Visually compare the displayed curve to the one you see in Calibration Flow — the shape should be identical, modulo the display resolution of the two interfaces.