What is error level analysis (ELA)?

When a JPEG image is saved again, areas that were already compressed at the same quality change very little, while areas added or edited later often change more. Error level analysis recompresses the image and maps the difference.

Our version divides the difference by the local texture of each block, because detailed areas naturally show higher error. Bright blocks in the map are regions that stand out after this correction.

ELA can point to local editing, but text overlays, sharp graphics and resizing produce similar patterns. It says little about whether an image was entirely generated by AI.