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Fooocus image detector: when the PNG carries a prompt

Fooocus writes generation metadata into its PNGs only when “Save Metadata to Images” is enabled (its default is off), using either its native fooocus JSON scheme or the A1111 plain-text scheme, and isGenAI reads the A1111 scheme as a saved prompt.

Facts checked against vendor documentation in October 2026. Updated .

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Controlled example PNG file that carries this record: Saved prompt found

parameters-tEXt.pngPNG file · controlled example

  1. Signature + IHDR
  2. iTXt XML:com.adobe.xmp
  3. tEXt parametersrecord
  4. tEXt prompt / workflow
  5. tEXt invokeai_metadata
  6. eXIf
  7. caBX C2PA manifest
  8. IDAT pixels
  9. IEND

Saved prompt found

The generator wrote its settings into the file.

Prompt, negative prompt, seed, sampler and model are read word for word, with the field they came from.

Open the prompt extractor →
Saved prompt found: where this record sits inside a PNG file and what the isGenAI report says about it. The picture is a code-drawn controlled example that carries this record; download it and check it yourself.

What Fooocus writes and when

Fooocus’s configuration sets default_save_metadata_to_images to false and default_metadata_scheme to fooocus. With saving enabled, the native scheme stores a JSON record of prompt, styles, model and settings; the a1111 scheme stores the same information as AUTOMATIC1111-style plain text, which is what galleries such as Civitai parse. A --disable-metadata flag also exists.

So a Fooocus PNG from an untouched installation usually carries no record at all.

What isGenAI reads

isGenAI reads the A1111 plain-text scheme from the parameters chunk and reports the prompt, negative prompt, seed, steps, sampler and model. The native fooocus JSON scheme is not parsed as a prompt; AI statements inside it are quoted as declarations if present, and the EXIF viewer shows the raw text.

A file with no record returns “no evidence found”, and the report explains that absence proves nothing.

Advice for Fooocus users and checkers

If you want your Fooocus images to be readable by the widest set of tools, enable metadata saving and choose the a1111 scheme. If you are checking someone else’s Fooocus image, expect nothing unless they changed the default.

Any re-encode removes the record, so always request the original PNG.

How to check an image from this generator

  1. Get the original download, not a screenshot or a copy saved from a chat or social feed.
  2. Upload it to the free AI image detector. Files up to 20 MiB in PNG, JPEG, WebP, AVIF or TIFF are read on the server and are private by default.
  3. Open “How we checked” and read each finding with its source field: signed record, declared source type, saved prompt, AI statement or matching copy.
  4. Treat a clean result as “no evidence found”, never as proof that a person made the picture.

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Frequently asked questions

Does Fooocus add metadata to images?

Only when Save Metadata to Images is enabled; the configuration default is off. It then uses the fooocus JSON scheme by default or the A1111 plain-text scheme if selected.

Can isGenAI read Fooocus metadata?

It reads the A1111 scheme as a saved prompt. The native fooocus JSON scheme is not parsed into a prompt, though the EXIF viewer shows its text.

Is a Fooocus image detectable after a screenshot?

No. Screenshots remove PNG text chunks and isGenAI does not infer origin from pixels.

Which scheme should I choose for compatibility?

The a1111 plain-text scheme is read by isGenAI and by most gallery parsers; the native scheme is read mainly by Fooocus itself.

Sources

Vendor behaviour changes. These pages describe what the vendor documents and what isGenAI reads from a file; they do not test every release.