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Silverlog

Calibration Step Chart

Generate a step chart for calibrating digital negatives used in alternative photographic processes. Print on transparency film and contact-print to measure tonal response.

Generate step chart

Choose your chart parameters, then download or print

Number of steps
Step distribution

Evenly spaced values from 0% to 100%.

Orientation

Preview (linear)

0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%

21 steps, 0% to 100%

A step chart is a series of grey patches ranging from pure white to pure black. It is the foundation of digital negative calibration for alternative photographic processes.

Workflow

  1. Generate a step chart with this tool and print it onto transparency film (OHP or inkjet-specific transparency media).
  2. Contact-print the transparency onto your chosen alt process paper (cyanotype, platinum/palladium, gum bichromate, etc.) using your standard UV exposure.
  3. Process and dry the print, then measure or visually compare each step to determine which tones your process can reproduce.
  4. Use the results to build a correction curve in Photoshop, GIMP, or a dedicated curve tool so that your digital negatives produce a full tonal range.

Linear vs logarithmic

Linear distributes steps evenly (e.g. 0%, 5%, 10%...) and is a good starting point. Logarithmic packs more steps into the shadow region where most alternative processes have the most tonal variation, giving you finer control where it matters most.

Printing tips

  • 1Use proper transparency media — inkjet transparency film (e.g. Pictorico Ultra Premium OHP) gives much denser blacks than standard overhead projector film.
  • 2Disable colour management — in your printer driver, turn off all colour corrections and ICC profiles. Print in greyscale only.
  • 3Print at 100% — make sure your application is not scaling the chart. The SVG is sized to the exact dimensions you selected.
  • 4Let the print dry completely — cyanotypes and other alt process prints shift significantly as they dry and oxidise. Evaluate after 24 hours for best accuracy.
  • 521 steps is a good default — 11 steps works for a quick check, 31 gives maximum precision but needs a larger print size so the patches stay readable.

Next step: once you have your calibration print, read our Digital Negatives guide to learn how to build a correction curve from your step chart results.

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