How ELA works
Error Level Analysis re-saves the image as JPEG at a known quality level, then computes the pixel-by-pixel difference between the original and re-saved version. Unedited regions that were compressed uniformly show similar error levels across the image. Manipulated areas — pasted objects, cloned regions, retouched faces — were compressed differently and produce noticeably higher or lower error values. The difference is amplified and displayed as a color heatmap where bright patches indicate potential edits. For double-compression detection that complements ELA, try the JPEG Ghost Scanner. For a metadata-based approach, see the Authenticity Checker.