False Positive (ELA)
Definition
An ELA anomaly in a region that was not manipulated, typically caused by high-frequency texture, JPEG artefacts in the original, or camera processing rather than post-capture editing.
- Field
- Error Level Analysis (image forensics)
- Common cause
- High-frequency texture, edges, or pre-existing JPEG artefacts
- Also caused by
- In-camera processing (sharpening, noise reduction)
- Practical effect
- ELA cannot be read as a standalone manipulation proof
Common questions
How does an examiner tell a real edit from an ELA false positive?+
By checking whether the bright region corresponds to a plausible edit boundary (a pasted object edge, a cloned area) versus a natural high-contrast feature such as text, hair, or a busy background, and by cross-checking with other tools like noise analysis or metadata review rather than ELA alone.
Why do repeatedly saved JPEGs produce more ELA false positives?+
Each re-save recompresses the image and shifts the error levels across the whole frame, not just at edited regions, so a heavily recompressed but untouched photo can show ELA brightness that looks like tampering.
Related terms
- Compression Equilibrium
- The state of an image region after sufficient JPEG compression cycles at a given quality: further compression at the same quality produces...
- ELA Amplification Factor
- The multiplier applied to the per-pixel difference before display. A higher factor reveals subtle differences but also amplifies noise, making regions look...
- ELA (Error Level Analysis)
- A passive image forensics technique that re-saves the input image at a chosen JPEG quality and amplifies the per-pixel absolute difference to...
- High-Frequency Detail
- Fine textures, sharp edges, and small text that JPEG compresses poorly. These regions inherently show high ELA values in authentic, unmodified images...
- Saturation
- In ELA context, the condition where a region's error level has reached near-zero, indicating it has already been compressed to near-equilibrium. A...