Recover a faded thermal receipt

Thermal paper goes from readable to blank faster than almost anything else you will handle. The good news is that 'blank' usually is not.

What is left

Thermal print heads apply pressure as well as heat. That pressure leaves a physical impression that outlives the visible darkening, and there is usually residual coating differential far below what a scanner's contrast curve can pick up. Both are recoverable structurally - neither is recoverable by turning up contrast.

Capture technique matters more here than anywhere

1. 1Flatten a crumpled receipt under a book overnight first. Fold shadows break digit shapes, and a broken digit is a misread digit.
2. 2Use raking light - a lamp low and to one side. This is the one case where oblique light beats flat light, because you are photographing an impression, not a print.
3. 3Capture the full receipt including the header, so the merchant, date and account are available.
4. 4Do not use flash. It flattens exactly the relief you are trying to record.

Run recovery, then reconciliation

Thermal recovery pushes the surviving stroke evidence back to readable density. Then run figure capture: the amounts, dates and references are read into a table, and the captured lines are totalled against their column.

When nothing comes back

Sometimes the coating is genuinely gone and the impression too shallow. The field is then withheld and marked rather than estimated. On a financial document that is the only acceptable outcome: a plausible invented figure will pass review and be wrong.