alt Hacker NewsThere are ways to tell if an image is real, if it's been signed cryptographically by the camera for example, but increasingly it probably won't be possible to tell if something is fake. Even if there's some kind of hidden watermark embedded in the pixels, you can process it with img2img in another tool and get rid of the watermark. Exif data, etc is irrelevant, you can get rid of it easily or fake it.
Sure, you can always remove it, but an average person posting AI images on Facebook or whatever probably won't bother. I was skeptical of Google's SynthID when I first heard about it but I've been seeing it used to identify suspected AI images on Reddit recently (the example I saw today was cropped and lightly edited with a filter but still got flagged correctly) and it's cool to have a hard data point when present. It won't help with bad/manipulative actors but a decent mitigation for the low effort slop scenario since it can survive the kind of basic editing a regular person knows how to do on their phone and typical compression when uploading/serving.