ELA (Error Level Analysis)
Definition
A passive image forensics technique that re-saves the input image at a chosen JPEG quality and amplifies the per-pixel absolute difference to reveal regions at different compression equilibria.
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...
- False positive (ELA)
- An ELA anomaly in a region that was not manipulated, typically caused by high-frequency texture, JPEG artefacts in the original, or camera...
- 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...
Explained in
- Error Level Analysis (ELA)A passive image forensics technique that re-saves the input image at a chosen JPEG quality and amplifies the per-pixel absolute difference to reveal regions at...