Remove selected prompt, workflow and parameters chunks from a PNG copy

Start with a defined five-field input and keep it

Download private-workflow.png and retain it as the original. It is a self-authored 1 × 1 PNG with five text occurrences: Author, Software, parameters, workflow and prompt. The three workflow-related fields contain fictional private text, including Project Cedar and an example.invalid address. The parameters seed is the exact token 18446744073709551615.

This exercise deletes only parameters, workflow and prompt. Author and Software deliberately remain. Its result is a verified selected-field edit, not an anonymous image or a complete privacy audit. Pixels can themselves disclose information, and other containers, unknown text keywords or embedded credentials need separate review.

• Download the PNG with fictional private text — Project-authored 1 × 1 PNG with five text occurrences. parameters, workflow and prompt contain the exported fictional text fixtures; Author and Software remain separate fields.
• Download the defined three-field removal control — Only the specified parameters, workflow and prompt occurrences are deleted. Author, Software and original IDAT bytes remain. This copy is not described as anonymous.
• W3C PNG Third Edition, fixed 24 June 2025 recommendation — Primary reference for text chunks, chunk ordering and CRC. Removing selected text does not remove every possible declaration or re-sign an embedded credential.

Identify the occurrences before staging removal

1. Step 1

   Read the original stored text

   Open Stable Diffusion PNG info and choose private-workflow.png. Inspect all five fields and their chunk positions. The three target occurrences are parameters at chunk-4, workflow at chunk-5 and prompt at chunk-7. prompt is stored after IDAT; do not stop looking when the image-data chunk begins.

   Read the original PNG fields

2. Step 2

   Choose the same original in the editor

   Open the PNG text editor and select private-workflow.png. Match both each keyword and occurrence ID. Stage deletion for chunk-4 parameters, chunk-5 workflow and chunk-7 prompt. Pending changes should list exactly three deletions. If your own file has duplicate keywords, inspect each occurrence; deleting one occurrence does not remove every field with that keyword.

   Open the local PNG text editor

3. Step 3

   Create and save the verified copy

   Click Create PNG from 3 staged changes, then Download verified PNG. Save edited-text.png separately from the original. The editor constructs new bytes and checks the resulting PNG; the three target chunks are removed rather than merely hidden from the display.

4. Step 4

   Re-read the actual download

   Choose edited-text.png in the PNG reader. Expect two text fields, Author and Software, with no parameters, workflow or prompt occurrence. Compare it with the downloadable private-text-removed.png control. The absence claim applies to these exact stored fields in this explicit local edit.

Verify the image-data boundary and the retained fields

Open the original and downloaded copy in PNG chunk inspector and save their structure reports. The target text rows disappear, later offsets can move, and IDAT stays an image-data chunk with its original payload. The writer's verification and independent raw-byte comparison check that the original IDAT bytes are unchanged; matching a displayed length alone would not establish byte equality.

Author and Software should still be readable with their original values. Removing selected text does not recompute an embedded C2PA signature. If a credential chunk remains, an edit can affect what a separate validator concludes; this tool neither re-signs it nor authenticates your file. Preserve the original for provenance or troubleshooting.

• Inspect chunk positions and CRC results — A complete container report includes text after IDAT and unknown ancillary chunks.
• Review supported remaining metadata categories — No findings in a bounded field scan is not proof that an image reveals nothing.

Use broader removal only when that is the intended policy

If you deliberately want every supported PNG text chunk removed, use Remove metadata and choose the PNG text category, then re-read its downloaded copy. That broader action also removes Author and Software in this fixture; it is a different policy from the three selected deletions above. Review the other category selections and color-profile choice before creating a copy.

The text editor rejects APNG rather than silently dropping frames, as well as a bad CRC or unsupported critical structure. Its limits include 10 MiB, 32 text fields, 256 KiB per field, 1 MiB total text and 64 staged operations. A rejected input or failed write is not successful removal. Keep the original and use a supported nonanimated copy only when that conversion is separately intended.

• Choose a broader whole-category removal policy — Review actual removed/retained categories and verify the output separately.
• Share a separate diagnostic document instead — Its default omissions do not change or clean this PNG.

Sources and reproducible inputs

• Download the PNG with fictional private text — Project-authored 1 × 1 PNG with five text occurrences. parameters, workflow and prompt contain the exported fictional text fixtures; Author and Software remain separate fields.
• Download the defined three-field removal control — Only the specified parameters, workflow and prompt occurrences are deleted. Author, Software and original IDAT bytes remain. This copy is not described as anonymous.
• W3C PNG Third Edition, fixed 24 June 2025 recommendation — Primary reference for text chunks, chunk ordering and CRC. Removing selected text does not remove every possible declaration or re-sign an embedded credential.