The short answer
You can rarely prove an image was edited from the file alone. You can often find signals: editor software tags, missing original capture data, re-encode evidence, structural oddities. Weigh them together and, usually, a picture emerges — literally.
Signal 1: Software traces
Editors and apps often leave their name in metadata: Photoshop, Lightroom, Snapseed, Canva in EXIF's Software field or XMP's history. This is one of the strongest hints — but only for the last save. A strip-and-export workflow leaves nothing, and platforms overwrite it. PictureMatters surfaces these as "processing trail" markers.
Signal 2: Missing original metadata
A "photo from a camera" with no camera EXIF at all is suspicious in contexts where originals are claimed. Careful though: sharing strips metadata too. The useful question is whether the story around the file matches its metadata survival — a news photo posted as "original" with zero EXIF deserves questions.
Signal 3: Compression and structure
- Progressive JPEG — cameras shoot baseline; progressive encoding typically means a re-save or platform re-compression.
- Double compression — quality-estimate patterns can indicate the file was JPEG-compressed more than once.
- Appended data — bytes after the image's end marker suggest someone modified the file container; sometimes editors, sometimes smuggled payloads.
- Wrong dimensions for the claim — a "RAW original" at 1080×1350 is a repost, not an original.
PictureMatters reports all of these in the structure map, encoding card and trailing-data card of every report.
Signal 4: Hashes and history
If you have a claimed original, compare SHA-256: different hash means the file changed at the byte level (though not necessarily visually — that's what the perceptual fingerprint is for). For published images, reverse-image search finds earlier versions to compare against.
What does not work
- "It looks AI/edited" — human judgment of pixels is unreliable and increasingly moot.
- Missing metadata = fake — absence is normal; see above.
- Single-signal certainty — one weak signal proves nothing; weight comes from convergence.
Run a check now
Upload the image to PictureMatters image forensics — you'll get the software trail, structure map, encoding facts, entropy profile and a journey classification in one report, with facts separated from interpretation. Free, no account.