合成画像の検出

It is different from verifying an image’s source or deciding whether the depicted claim is true. Detector outputs require careful interpretation because false positives and false negatives can both occur.

主なポイント

• Check evaluation conditions and base rates.
• Separate detection from provenance and truth.
• Preserve uncertainty in decisions about people.

Read the evaluation conditions. A detector trained on one set of generators may perform differently on newer models, edited outputs, screenshots, or recompressed images. A reported score from a balanced benchmark may not describe a real collection with very few synthetic images. Distinguish the detector’s score from an established probability. Calibration, threshold choice, and the prevalence of synthetic content affect interpretation. A high score can be a reason to investigate without justifying a public accusation. Use complementary evidence: original files, source history, metadata, content credentials, and independent corroboration. Metadata can be missing or altered, and credentials describe recorded provenance rather than guaranteeing that every visual claim is true. Design a review workflow that accounts for uncertainty. Preserve evidence, document the tools and versions used, and explain the basis for any conclusion. Avoid automatically penalizing people based on a single unvalidated detector result.

1. Construct a collection of 1,000 genuine images and 10 synthetic images. Suppose a detector flags 1% of genuine images and catches 8 synthetic ones.
2. It produces 10 false alarms and 8 true detections, so only 8 of 18 flagged images are synthetic in this example.
3. Report the actual counts and review the evidence before making a claim about any image.

The invented figures illustrate base-rate effects, not the performance of a real detector.