Calibration Flow offers six standard test charts that cover the vast majority of practical cases — A4 portrait, A4 landscape, three positive polarities, three negative polarities, with or without dithering. For the everyday calibration of a cyanotype, an Aquaprint or a carbon on A4 paper, it's enough.
But some needs fall outside these six variants. A 200 × 200 mm square print. A test strip with 5 patches instead of 25. An A3 chart for the large format. An unusual format specific to your workflow. For these cases, custom test chart creation would be the right tool.
This feature is currently being integrated into Calibration Flow. It isn't available today. This page documents what it will do once it's ready, and offers workarounds for urgent needs.
#What's planned
When the feature is integrated, the creation screen will let you define the chart's dimensions to suit your need (standard formats such as A5, A3, square, or custom dimensions), choose the polarity (positive for resinotype, negative for the rest), and adjust the print settings. The exact details of the parameters exposed to the user will be documented on this page the day the feature ships — not before, so as not to announce anything that might change in the meantime.
The tool will generate a ready-to-print high-resolution PNG, in the same format as the six standard charts.
#Workarounds for urgent needs
While waiting for the integration, three options for unusual formats:
First — Photoshop as a generator. You can build a custom chart in Photoshop from a standard Calibration Flow chart. Download the plain A4 chart in negative polarity, open it in Photoshop, resize to the desired format (for instance a 200 × 200 mm square), recrop the patches if needed, save the PNG. It's laborious but it works for one-off needs.
Second — A4 output then physical cropping. Print the standard A4 chart, then physically cut it to the final format (for instance a square format cut out of the A4). You lose a few patches in the crop if you cut too close, but for most reasonable formats, it's enough.
Third — improvised test strip. For a quick 5-patch test strip, generate a standard 25-patch chart and visually use only the first row for your test. Not optimal, but it spares you waiting for the feature.
#Why this feature isn't here yet
A custom-chart generation feature looks simple on the surface — a few sliders to choose the format, a button to generate. Under the hood, it requires handling several things correctly: the mathematical consistency between patches (so the measurement stays valid at different dimensions), the dithering adapted to the chosen resolution, and the compatibility with the app's measurement pipeline so the patches are correctly recognized at scan time.
The Calibration Flow team prefers to ship this feature when it's genuinely robust rather than ship an incomplete version that would produce charts usable only 70% of the time. It's consistent with the rest of the app — every feature is finished or explicitly marked "upcoming", not approximate.
#Key points
| Element | Status |
|---|---|
| Feature available | No — being integrated |
| Six standard charts | Available in the menu — see Types of test chart |
| Workaround 1 | Building in Photoshop from a standard chart |
| Workaround 2 | Physical cropping after printing |
| Workaround 3 | Partial use of a 25-patch chart as a test strip |
| Planned access mode | Undefined — to be confirmed when the feature is integrated |
#In the meantime
If you have an urgent need for a custom chart for a project in progress, the Photoshop workaround is probably the fastest — count on 15 minutes to build your own chart from a downloaded standard chart. For recurring needs (for instance if you regularly work in square format), keep a Photoshop template file that you reuse.
When the feature is integrated into Calibration Flow, this page will be updated with the full instructions. In the meantime, report your priority needs to
support@picturale.app