isGenAI.com

AI image detector by file format

JPEG AI image detector: what the APP segments hold

A JPEG stores its provenance in application segments: EXIF and XMP in APP1, IPTC-IIM in APP13 and C2PA manifests in APP11 JUMBF boxes, and isGenAI reads the signed manifest, the IPTC DigitalSourceType, AI statements and AUTOMATIC1111 prompts kept in EXIF UserComment.

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

Check an image nowFrequently asked questions
Controlled example JPEG file that carries this record: Saved prompt found

a1111-jpeg.jpgJPEG file · controlled example

  1. SOI
  2. APP1 Exif · UserCommentrecord
  3. APP1 XMP
  4. APP11 JUMBF · C2PA
  5. DQT · SOF · DHT
  6. SOS pixels
  7. EOI

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 JPEG 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 JPEG keeps provenance

JPEG files are sequences of marker segments. EXIF lives in an APP1 segment beginning with Exif, XMP in an APP1 segment beginning with the Adobe namespace, legacy IPTC-IIM in APP13, and C2PA Content Credentials in one or more APP11 segments holding a JUMBF box, as the C2PA specification defines. Generators that mark images, including those using IPTC’s DigitalSourceType, usually write the value into XMP.

AUTOMATIC1111 stores its generation parameters in EXIF UserComment for JPEG output, using a UTF-16 encoding.

What isGenAI reads from a JPEG

The AI image detector accepts JPEG up to 20 MiB, validates the C2PA manifest, reads XMP for the IPTC source type, quotes AI statements found in EXIF, XMP or IPTC text, and reads the A1111 record from UserComment. The EXIF viewer shows camera make, lens, dates and GPS in your browser and validates the segment structure first. The metadata remover accepts JPEG and outputs a clean PNG.

Each finding is labelled with its segment so a signed manifest is never confused with an editable XMP field.

Compression and conversion

Re-saving a JPEG at a new quality rewrites the pixels and, in most apps, drops the APP segments; it also breaks any C2PA hash binding. The image compressor and converter produce fresh files without metadata. For evidence, keep the first JPEG you received and work on copies.

JPEG cannot hold transparency; that matters for conversion, not provenance.

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.

Check an image now

Frequently asked questions

Can a JPEG contain an AI prompt?

Yes, when AUTOMATIC1111 saved it: the parameters go into EXIF UserComment. isGenAI reads that record from the original JPEG.

Does a JPEG keep C2PA Content Credentials?

Yes. C2PA defines APP11 JUMBF segments for JPEG, and isGenAI validates the manifest in the AI image detector and the C2PA checker.

Why did compressing the JPEG remove the evidence?

Re-encoding rewrites the file; most encoders discard APP segments and any manifest hash no longer matches. Compress a copy, check the original.

What does the EXIF viewer show for a JPEG?

Camera, lens, exposure, dates, software and GPS fields read in your browser, with structure checks that refuse a truncated or malformed file.

Sources

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