isGenAI.com

AI image detector by generator

FLUX AI image detector: signed credentials or saved graph

A FLUX image from the Black Forest Labs API or Playground carries C2PA Content Credentials that isGenAI validates, while a FLUX image rendered locally in ComfyUI carries an unsigned prompt graph that isGenAI reads instead.

Facts checked against vendor documentation in October 2026. Updated .

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Code-drawn illustration for FLUX

Illustration · PNG file

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

AI source type declared

The file labels itself as AI-made.

IPTC DigitalSourceType such as trainedAlgorithmicMedia is read from XMP and shown with its exact value.

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AI source type declared: where this record sits inside a PNG file and what the isGenAI report says about it. The picture is a code-drawn illustration.

Two very different FLUX files

Black Forest Labs documents that Content Credentials are attached to all images generated through the BFL API, the Developer Playground and BFL-controlled hosted integrations, and that BFL does not attach or validate credentials for outputs from third-party or self-hosted deployments. The same article warns that social platforms strip metadata and that editing, cropping or compressing after signing causes a hash mismatch.

Open-weight FLUX models run in ComfyUI or InvokeAI write no credential. ComfyUI saves the prompt graph in the PNG; InvokeAI records flux_txt2img as the generation mode.

What isGenAI shows

For an API or Playground download, the report lists a signed creation record with validation state, trust state and the recorded AI action. For a local render, the checker follows the ComfyUI graph through CLIPTextEncodeFlux and FluxGuidance nodes to the sampler and reports the saved prompt when the two text encoders agree, or a saved workflow when they do not.

Both results name the exact field they came from, so a signed BFL credential is never confused with an editable text chunk.

What survives sharing

Neither the manifest nor the text chunk survives a screenshot or a typical social upload. Ask for the original file from the API response or the ComfyUI output folder.

If you suspect a FLUX image was edited after signing, the C2PA checker shows the broken binding; the image metadata compare tool shows which records were lost.

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 FLUX add C2PA metadata?

Yes for images generated through the Black Forest Labs API, Developer Playground and BFL-hosted integrations, per BFL’s help centre. Self-hosted FLUX outputs get no credential from BFL.

What does a local FLUX render in ComfyUI contain?

The ComfyUI prompt graph and workflow in PNG text chunks. isGenAI reads the graph, including CLIPTextEncodeFlux and FluxGuidance nodes, and reports the saved prompt or workflow.

Is a FLUX image detectable after a screenshot?

No. The manifest and the text chunks are gone, and isGenAI does not infer origin from pixels. Obtain the original download.

Why does the credential show as invalid?

BFL notes that editing, cropping, compression or watermarking after signing causes a hash mismatch. isGenAI reports the broken binding instead of hiding it.

Sources

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