Changing a total on a receipt, a date on a certificate or a message in a screenshot takes a minute. Spotting it by eye is hard, because the change is usually a few characters. Here's where to look, and where the limits are.
Where edits happen
Look hardest at the fields that matter: totals, dates, names, grades, account numbers and bank details. Edited text often differs slightly from the text around it:
- a different sharpness or a faint halo around the characters
- letters that sit a pixel higher or lower than their neighbours
- a font weight or spacing that doesn't quite match
- a background behind the text that is smoother or noisier than the rest of the page
Photos and scans of documents
A photo of a receipt or a scan of a certificate should come straight from a phone camera or a scanner. Upload it to snapWONDERS and look at:
- what last saved the file. Camera or scanner output is expected; an image editor is worth a question.
- signs it was compressed twice, which happens when a file is opened, changed and saved again.
- a region that compresses differently from the rest of the page, such as a pasted-in number.
A worked example: one receipt, one changed number
We photographed one of our own receipts on a phone, then made a copy and changed the total from $58.70 to $88.70 by copying the receipt's own "8" over the "5", the way a forger would. (We've blurred the reference numbers and card details in these pictures; the files we checked were not blurred.)
By eye, the altered copy is hard to fault. Both copies even got the same Authenticity grade, B, because the report grades the file, not the arithmetic on the paper. The difference is in the details. On the genuine photo, the compression settings match the phone's camera, and the phone's own records sit after the image:
On the altered copy, the compression settings belong to editing software, and the phone's records are gone. The report's originality assessment drops from Consistent with original to Inconclusive:
So the report tells you the file was saved again by software after the camera. It doesn't point at which number changed. The receipt itself does: GST is still $5.36. GST is one eleventh of a total that includes it: about $5.34 on $58.70, but about $8.07 on $88.70. Always check that the numbers add up.
See it as a before and after: the receipt total that changed
Screenshots: the hard case
A screenshot is a fresh image created by your phone at the moment you took it. Whatever was on screen, real or edited, becomes a clean new file. So a check can tell you a screenshot is a screenshot, and whether it was edited after it was taken, but it can't tell you whether the conversation or balance on screen was real.
For anything that matters, ask for the original: the email itself, the PDF invoice, the bank's own confirmation. Screenshots of payments are the most common fake of all.
Confirm with the source
A clean result means the file shows no sign of editing. It doesn't mean the receipt was issued or the certificate awarded. For anything important, confirm with the issuer using contact details you already hold, never the ones printed on the document.
