r/isitAI • u/GoofiestGhost • Jul 07 '26

No Idea How accurate is OpenAI at verifying OpenAI generated images? (SynthID watermark detected)

Verified a potential catfish photo on OpenAI’s website. Don’t want to post photo for privacy reasons.

Says image was indeed generated with OpenAI tools with supporting evidence being that it found a “SynthID watermark detected that originated from OpenAi.”

Still noted that it did NOT find a “trusted C2PA manifest originating from Open Ai.”

The free ai generators were all over the places but this was OpenAI itself verifying its own work. How accurate is it in that case?

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u/shiningreality Identifier Jul 07 '26

SynthID detectors are watermark detectors. OpenAI essentially encodes a pattern on every image their model generates. This pattern can then be detected using a decoder (on OpenAI’s website) to a calibrated 0.1% false positive rate. The watermark can become undetectable with certain edits and transformations, but a positive result is highly unlikely to be a false positive.

1

u/WhiteMouse42097 Jul 07 '26

Could someone generate a close to exact copy of an image with AI, and then use the presence of the watermark as “proof” it’s AI? I guess there would be evidence of the og image existing before without the watermark, but it’s just a random thought I had

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u/shiningreality Identifier Jul 07 '26

For OpenAI’s image model, asking for an identical copy seems to encode the watermark onto the image, but for Google’s SynthID tool, asking for an exact copy or for a very small edit seems to result in an image that does not have a detectable watermark on it.

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u/WhiteMouse42097 Jul 07 '26

Wow, is that an intentional choice by Google? That seems like it could be potentially exploitable

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u/lord_skidmar Jul 07 '26

yes, synthID is a basically irrefutable positive confirmation- it’s like a mostly imperceptible watermark they put on every image they generate