Check whether copied PDF text preserves readable characters

Where the extra work starts

Check a representative line first so you can choose a workable input route before processing the whole file.

ParseMill processes native invoice PDFs and clear printed English PDF scans. Try a typical supplier invoice and a difficult one. Check the extracted fields, correct exceptions and open the workbook before committing to a monthly plan.

This is a diagnostic sample. Passing three checks does not establish that every character or table relationship in the document is correct.

A practical way to get it right

Use the viewer's text-selection tool on the actual document, then paste into a plain-text area in an approved local application. Avoid a screenshot or snapshot, which may copy an image rather than text. Compare each character, including zeros, letter O, decimal marks, minus signs and spaces.

Copy one field at a time first, then a short row and heading sequence. This separates character problems from reading-order problems. Record the exact source location and the observed pasted value. If a character changes, keep both versions and classify the issue rather than silently correcting the test result.

Inspect a second page or a different table region if the document varies. A single good heading can coexist with image-only pages, OCR errors or a different font elsewhere. In ParseMill, textless invoice pages use English OCR; an existing but garbled text layer is not automatically repaired by that fallback. Use the findings to plan source checks or choose a reviewed manual route.

Adobe: Copy content from PDFs describes text selection and copying and how to check document restrictions. Diagnose the failure type before choosing a repair.

What this looks like on a real task

Synthetic example. The people, references and figures below are invented to demonstrate the method.

The document has both a character mismatch and a sequence problem despite two successful fields. Copy the sample, pasted text and finding columns. The synthetic O017 example is deliberately ambiguous to the eye, so inspect the original at readable magnification rather than assuming the pasted value is authoritative.

Catch the cases that create rework

If copying is disabled, investigate permissions before labeling the file image-only. If selection captures an entire region as an image, use the appropriate text tool and inspect whether a text layer exists. Do not bypass restrictions to complete a fit test.

A flat pasted row can lose column relationships even when every character is correct. Preserve the visual source and check geometry separately before mapping values into fields.

W3C: PDF reading order explains that logical reading order depends on PDF structure. A visually correct page can therefore need a separate sequence check when text is reused.

Decide whether the change is worth keeping

The fit note should state what was sampled, which characters or sequences failed and what remains untested. For a bounded extraction trial, include the problematic fields in acceptance checks and retain raw output. A readable screen and selectable text are useful starting observations, but source-backed review is still required before treating an export as reliable.