isGenAI.com

AI image detector by file format

WebP AI image detector: RIFF chunks that carry provenance

WebP stores provenance in named RIFF chunks, EXIF and XMP for metadata and a C2PA chunk for Content Credentials, and isGenAI reads the signed manifest, the IPTC source type in XMP, AI statements and AUTOMATIC1111 prompts kept in EXIF UserComment from an original WebP.

Tool support and container facts as of October 2026. Updated .

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

a1111-webp.webpWebP file · controlled example

  1. RIFF · VP8X
  2. EXIFrecord
  3. XMP
  4. C2PA
  5. VP8 pixels

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 WebP 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.

Where WebP keeps provenance

A WebP file is a RIFF container. Extended WebP files declare which optional chunks they carry: EXIF for Exif data, XMP for an XMP packet, ALPH for transparency and ANIM for animation. The C2PA specification defines a dedicated chunk for the manifest store. ChatGPT serves many generated images as WebP, and OpenAI documents the C2PA manifest adding noticeably to a WebP’s size.

AUTOMATIC1111 writes its generation parameters to EXIF UserComment in WebP output just as it does for JPEG.

What isGenAI reads from a WebP

The AI image detector accepts WebP up to 20 MiB, validates the C2PA manifest, reads the IPTC DigitalSourceType from the XMP chunk, quotes AI statements and reads the A1111 record from EXIF. The EXIF viewer checks the RIFF structure and lists readable fields. The metadata remover accepts still WebP and outputs a clean PNG; the C2PA checker validates WebP manifests too.

Animated WebP is refused by the remover; the detector reads the first image’s records.

Converting WebP

The WebP to PNG page converts in your browser and writes a new PNG without the EXIF, XMP or C2PA chunks. Use it for compatibility, not for evidence. Keep the original WebP to check, and compare both with the image metadata compare tool to see what the PNG lacks.

WebP keeps transparency, so conversion to PNG loses nothing visual.

How to check a file in this format

  1. Keep the original bytes. Do not open and re-save the file in an editor before checking it.
  2. Use the tool that accepts the format: the AI image detector for PNG, JPEG, WebP, AVIF and TIFF; the C2PA checker for those plus HEIC, PDF, MP4 and MOV.
  3. Read each finding with its source field. The report names the container record it came from.
  4. If you must convert, convert a copy and compare both files with the image metadata compare tool so you know what the conversion dropped.

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Frequently asked questions

Can a WebP carry C2PA Content Credentials?

Yes. The C2PA specification defines a C2PA chunk in the RIFF container, and ChatGPT WebP downloads are a common example. isGenAI validates the manifest.

Does a WebP keep EXIF and XMP?

Yes, in EXIF and XMP chunks. isGenAI reads the IPTC source type from XMP and the A1111 prompt from EXIF UserComment.

Does converting WebP to PNG keep the credentials?

No. The browser-side converter writes a fresh PNG with no metadata chunks. Check the original WebP and convert a copy.

Can I remove metadata from a WebP?

Yes. The metadata remover accepts still WebP and produces a clean PNG, listing what it removed.

Sources

Container facts come from the published specifications. Tool support describes isGenAI as deployed in October 2026.