Perceptual hashing (duplicate detection)
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Purpose
Every receipt image submitted is converted to a perceptual hash — a digital fingerprint of the image content.
Best for
Understanding security measures and admin controls
Read time
1 min
Next action
Review how submissions are verified and protected
Every receipt image submitted is converted to a perceptual hash — a digital fingerprint of the image content. This hash is compared against all previously submitted receipt hashes. Even minor image edits (cropping, rotating, adjusting brightness) do not meaningfully change the hash. The same physical receipt photographed twice will produce matching hashes and fail Gate 9.