Evidence boundaries
Observation is not verification.
Model output is a visual hypothesis about pixels. File metadata is parsed from uploaded bytes. Cryptographic provenance and invisible watermarks require dedicated validators. Img ID presents these as separate evidence classes instead of blending them into one claim.
Pilot dataset
13 images, documented as a starting point.
| Class | Count | Recorded coverage |
|---|---|---|
| AI-generated | 9 | Four Midjourney, four Grok, one Gemini |
| Real photographs | 4 | Portrait, landmark, and landscape photos |
One changed result moves raw hit rate by 7.7 percentage points. Dataset also lacks a holdout split, broad camera coverage, editing history, transformation variants, and independent label review. These limits rule out a representative public accuracy claim.
Evaluation
Same prompt, same images, individual errors first.
Each candidate receives same image and detection prompt. Strong and soft AI or real verdicts are compared with recorded binary label. Uncertain answers abstain. Internal ranking rewards a correct confident direction, gives soft verdicts less weight, and penalizes confident errors more heavily.
Weighted score is a product heuristic, not calibrated probability or scientific metric. Model-reported confidence is not assumed to be calibrated. Reviews focus on false positives, false negatives, and uncertain cases rather than one headline number.
Reporting policy
Claims Img ID will and will not make.
- Call current set a pilot or regression set, not a representative benchmark.
- Report sample counts, run date, model identifier, prompt revision, and individual errors.
- Do not turn a 12-of-13 pilot result into a public accuracy claim.
- Do not claim model attribution unless a separate attribution evaluation supports it.
- Do not treat missing metadata as evidence that an image is AI-generated.
- Keep historical provider results labeled with date because hosted models can change.
Expansion plan
Path to a credible public benchmark.
- Collect at least 200 rights-cleared files with source, license, ground truth, edit history, and SHA-256 recorded.
- Balance real and AI classes, then lock a holdout set before model or prompt tuning.
- Cover current generators, varied cameras, people and places, screenshots, CGI, artwork, receipts, memes, and edited photos.
- Test cropping, resizing, filtering, recompression, screenshots, upscaling, and social-media re-encoding.
- Use independent review for ambiguous labels and exclude unresolved files from headline reporting.
- Publish false-positive, false-negative, abstention, calibration, and category-level results with uncertainty intervals.