# How to Tell If an Image Is AI-Generated (Without Trusting a Detector)

> Check the file, not the pixels: AI generators leave metadata receipts — IPTC labels, generator signatures, Content Credentials. What each proves, and why a clean result means nothing.

Source: https://toolpantry.app/blog/how-to-tell-if-an-image-is-ai-generated

## About

AI generators increasingly sign their output — IPTC labels, generator signatures, Content Credentials. Here's what each signal proves, what it doesn't, and why "no markers found" is not the same as "real".

## Quick answer

Short answer: run the file through the AI image checker first. If the creating tool wrote an AI label, a generator signature, or Content Credentials, you have a receipt — strong evidence. If the metadata is gone (typical after any social upload), no honest tool can tell from pixels alone, and the pixel-based "detectors" that claim otherwise don't publish their error rates.

## The receipt test, in 30 seconds

1. Open **toolpantry.app/ai-image-checker** and add the file — original, not a screenshot of it.
2. Read the verdict: **AI markers found** (strong), **Content Credentials found** (verify at contentcredentials.org), or **no markers**.
3. If you need the full picture — GPS, camera, editing history — the [EXIF viewer](https://toolpantry.app/exif-viewer.html) shows every field the file carries.

## What we found in our test files

We ran three files through the checker. A Stable-Diffusion-style PNG carrying the Automatic1111 "parameters" chunk — the full prompt-and-sampler recipe many local generators embed — was flagged instantly as a strong AI signal. A camera JPEG with Canon EXIF and a Lightroom software tag came back clean, with camera metadata as context. And a screenshot of an AI image? Nothing. No metadata, no verdict — the file simply doesn't remember where it came from.

| Signal | Strength | What it proves |
|---|---|---|
| IPTC trainedAlgorithmicMedia label | **Strong** | The creating tool declared the image AI-generated — a direct statement in XMP |
| Generator signature (Midjourney, ComfyUI, NovelAI…) | **Strong** | The software that made the file signed it |
| Stable Diffusion "parameters" chunk | **Strong** | The generation recipe is embedded, prompt included |
| Content Credentials (C2PA) | Verify | Signed provenance — could be AI or a camera; verify the manifest itself |
| Camera EXIF | Context | A camera wrote the file — but AI tools can copy metadata |
| No metadata at all | Nothing | The file was stripped, re-saved, or screenshotted. Proves nothing |

## Why we don't do pixel-based detection

The "AI detector" industry sells probabilities. None of the major services publishes a real error rate, the generators improve every few months, and false positives have already ruined real people's work — teachers running essays through text detectors, stock photographers accused of generating their own photos. The honest position: when the label is in the file, you don't need a probability. When it isn't, we say so.

## The visual tells that are mostly dead

Wrong hands and garbled text were the classic 2023 tells. By late 2025, Gemini's Nano Banana Pro and OpenAI's GPT Image models largely fixed both — text rendering is now a selling point. What still trips generators: reflections that don't match the scene, text that drifts on the third repetition, and background people whose faces melt under zoom. Treat all of these as hints, never proof. A hint is enough for "look closer"; it is not enough to accuse.

## When this approach fails

Instagram, WhatsApp, and X re-encode every upload and drop the metadata. If an image reached you through a social platform, the receipt is gone — the checker will honestly tell you there's nothing to go on. Screenshots are worse: a screenshot never had metadata in the first place. And if you're the one holding evidence — a suspicious image someone sent you — **don't re-save, edit, or screenshot it**. Every one of those destroys the very fields that carry the proof. Keep the original file, check it, and share the check result alongside it.

## Where this is heading

Regulation is making labeling the default: the EU AI Act's transparency rules expect AI content to be marked, and cameras (Leica, Sony) now add C2PA Content Credentials on capture, as do most major generators. The practical habit for 2026 is simple — before you trust or forward an image, glance at the file, not just the picture.

## Notes

By the Tool Pantry team, October 2026. Tested with our own checker on a Stable-Diffusion-style PNG, a camera JPEG, and a stripped screenshot — results below.

## FAQ

**How can I tell if an image was made by AI?**

Check the file's metadata first: many AI tools write a generator signature, an IPTC trainedAlgorithmicMedia label, or Content Credentials into the image. Those are strong evidence when present. If the metadata is missing — common after any social upload — no honest tool can tell from the pixels alone.

**Are AI image detectors reliable?**

Pixel-based detectors publish no error rates and are in an arms race with generators; false positives have already harmed real people. Metadata is different — it is a statement written by the creating tool, not a probability.

**Why do AI images show no markers?**

Most generators don't write labels, and every major social platform re-encodes uploads, stripping metadata. Screenshots never had metadata. Absence of markers is not evidence either way.

**What should I do if I need to prove an image is AI-generated?**

Keep the original file exactly as it was downloaded and don't re-save, edit, or screenshot it. Re-saving destroys the very metadata that carries the proof. Check it with the AI image checker before sharing.