# How can you tell if an image is AI generated?

Source: https://forum.global100.org/q/how-can-you-tell-if-an-image-is-ai-generated/
Site: Global 100 Forum, category AI images and photos
Published: 2026-09-15. Updated: 2026-09-20. Replies: 1.

## Question by Tomas Reyes (staff), 2026-09-15

Usually you cannot tell with certainty from the pixels alone. The reliable route is provenance: Content Credentials or a SynthID watermark can positively confirm an AI origin, but only when the generator added them. Visual tells, reverse image search and detector tools give useful evidence, never proof, and the visual tells are fading with each model generation.

## Visual tells: what still works and what does not

Google's own [verification guidance](https://support.google.com/gemini/answer/16722517) lists the artefacts still worth checking: garbled or inconsistent text inside the image, errors in small details such as hands, teeth and background objects, shadows and lighting that do not agree, and unnaturally repetitive patterns.

What no longer works is treating a clean image as evidence of a real one. Extra fingers and melted jewellery were dependable signs in 2022-era models. Current models render hands and faces correctly most of the time, so the absence of mistakes tells you nothing. The [face thread](/q/can-people-reliably-spot-an-ai-generated-face-just-by-looking/) covers how poorly people do when they rely on looking alone.

## Reverse image search

Run the image through Google Images or TinEye and look for the earliest appearance. If the same picture predates the generator that supposedly made it, or appears in a photographer's archive or news wire, that is strong evidence it is real. If the only sources are recent social reposts, you have learned nothing either way.

## Metadata and Content Credentials

A camera writes EXIF data (model, lens, timestamp). It is easy to strip or forge, and screenshots discard it, so it is weak evidence on its own.

Content Credentials are stronger. The [C2PA specification](https://c2pa.org/specifications/specifications/2.2/specs/C2PA_Specification.html) defines a cryptographically signed manifest that records who or what produced the file and how it was edited. You can inspect a file at [verify.contentauthenticity.org](https://verify.contentauthenticity.org/). A valid manifest naming an AI tool is close to proof. The catch, stated in the specification itself, is that an asset can become separated from its manifest when metadata is removed, so a missing manifest proves nothing. The [C2PA thread](/q/what-is-c2pa-and-do-content-credentials-actually-help/) goes deeper.

## SynthID for Google images

[SynthID](https://deepmind.google/technologies/synthid/) embeds an invisible watermark in images made by Google's generative models, designed to survive cropping, filters and lossy compression. You can check a file by uploading it to the Gemini app and asking whether Google AI made it. Google's help page is explicit about the limit: Gemini currently recognises only Google-generated content, so "no watermark found" means "not Google", not "not AI". It also warns that very simple content or a tiny edit may carry no detectable watermark.

## Detector tools

Hive, Illuminarty and AI or Not are classifiers that return a probability. A 2024 study by [Ha and colleagues](https://arxiv.org/abs/2402.03214), tested them on art from five generators. Hive reached 98.03% accuracy with no false positives on unperturbed images, but its detection rate fell below 70% when images were protected with Glaze. Illuminarty scored 72.65% accuracy with a 67.40% false positive rate. AI or Not advertises 98.9% accuracy on its own site, which is a vendor claim, not an independent result.

**Six ways to check an image, and what each can actually prove**

| Method | What it can prove | Where it fails |
| --- | --- | --- |
| Visual inspection | Suggests AI when text or fine detail is broken | Clean output proves nothing; tells fade with each model |
| Reverse image search | Real, if the image predates the generator or has a documented source | Silent on new or private images |
| EXIF metadata | Weak support for a camera origin | Stripped by screenshots, trivially forged |
| Content Credentials (C2PA) | AI origin and edit history, when a signed manifest is present | Optional; lost when metadata is removed |
| SynthID via Gemini | Google AI origin, even after moderate edits | Other generators return no result; tiny edits may not carry it |
| Detector tools (Hive, Illuminarty, AI or Not) | A probability, useful as one signal | Adversarial edits, new generators, false positives on some tools |

## What that means in practice

- **Start with provenance, not pixels.** Check for Content Credentials first, then SynthID if a Google model is plausible.
- **Treat a detector score as one witness.** Combine it with reverse search and the story around the image.
- **Ask for the original file.** Screenshots and re-uploads destroy the metadata that could have settled the question.

## Reply 1 by Tomas Reyes (staff), 2026-09-20

One habit that saves time: before running any tool, ask where the image first appeared and who posted it. Most fakes that spread fast have no upstream source at all, and a five-minute search for the earliest copy answers more questions than a detector score. If you do need the Gemini SynthID check on a screenshot, crop tightly to the single image, because Google's help page says a loose crop or a collage lowers the chance of a detection.

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Cite as: Global 100 Forum, "How can you tell if an image is AI generated?", https://forum.global100.org/q/how-can-you-tell-if-an-image-is-ai-generated/, accessed 2026-10-11.