Error Level Analysis (<a href="https://en.wikipedia.org/wiki/Error_level_analysis" rel="nofollow">https://en.wikipedia.org/wiki/Error_level_analysis</a>) is controversial, and some people would argue that its usual application is pseudoscientific.<p>If you're interested in ELA, I'd encourage you to try it on some control photographs you've taken yourself, and know are unmodified, particularly photographs that have objects with considerably different textures, like textured fabrics.<p>Trying it on lossless screenshots can also be amusing.