# How do the vendors' docs describe mask-based editing and inpainting (mask format, polarity, fidelity), and what do they say the mask does not guarantee?

- id: art_01M5MC1A1ETZEEVXCWDV2FGQMN
- type: article · status: active · revision: 3
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T05, T16 · tags: none
- updated: 2026-10-24T22:52:52.143Z
- url: https://veyrul.com/articles/art_01M5MC1A1ETZEEVXCWDV2FGQMN

Corrected 2026-10-24 - see C3-B977-02; the original statements below are kept for history and are superseded where the correction says so. Mask formats are not interchangeable: OpenAI needs a same-size mask with an alpha channel and calls masking prompt-based (the model may not follow the exact shape); Ideogram uses black for the area to edit and white to keep, with a same-size mask that must contain both; Imagen takes a black-and-white mask or automatic background, foreground or semantic masks with a dilation setting and a sampling-step knob; Midjourney's editor now routes inpainting through the V8.X Edit Model. Ideogram 4.5 states that untouched pixels are copied exactly, the strongest fidelity claim among the pages read.

Mask formats are not interchangeable: OpenAI needs a same-size mask with an alpha channel and calls masking prompt-based (the model may not follow the exact shape); Ideogram uses black for the area to edit and white to keep, with a same-size mask that must contain both; Imagen takes a black-and-white mask or automatic background, foreground or semantic masks with a dilation setting and a sampling-step knob; Midjourney's editor now routes inpainting through the V8.X Edit Model. Ideogram 4.5 states that untouched pixels are copied exactly, the strongest fidelity claim among the pages read.

Curator correction 2026-10-24 (discovery C3-B977-02; sources re-fetched 2026-10-24, excerpts re-located by curator GET): The summary's Imagen clause (black-and-white mask or automatic background, foreground or semantic masks, dilation, sampling steps) is sourced from Vertex pages that now state 'Vertex AI documentation is no longer being updated' and list imagen-3.0-capability-001 and -002, the editing models, as discontinued endpoints with a June 30, 2026 service-disruption warning and replacement gemini-2.5-flash-image. The summary should say these Imagen editing parameters describe endpoints the Vertex page lists under "Discontinued endpoints", with a June 30, 2026 migration deadline in its caution box (the capability models' own discontinuation date lines were not read), not a current option. The OpenAI, Ideogram, and mask-format claims were re-read and still match (OpenAI guide now names gpt-image-2.5-sunburst and -flare; Ideogram 4.5 and 3.0 mask text unchanged); the Midjourney editor page returned HTTP 403 and was not rechecked.

Curator qualifications: All excerpts located; mask polarity/format non-interchangeable (Ideogram black=edit vs OpenAI alpha channel; alpha value unstated) kept.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://platform.openai.com/docs/guides/image-generation.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://developer.ideogram.ai/v2/api-reference/images/precise-edit/ideogram-4-5.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.cloud.google.com/vertex-ai/generative-ai/docs/image/edit-insert-objects",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://developer.ideogram.ai/v2/api-reference/images/inpaint/ideogram-3.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.midjourney.com/hc/en-us/articles/32764383466893-Editor",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.cloud.google.com/vertex-ai/generative-ai/docs/image/edit-images-overview",
      "note": "candidate evidence excerpts"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Curator correction 2026-10-24 (discovery C3-B977-02; sources re-fetched 2026-10-24, excerpts re-located by curator GET): The summary's Imagen clause (black-and-white mask or automatic background, foreground or semantic masks, dilation, sampling steps) is sourced from Vertex pages that now state 'Vertex AI documentation is no longer being updated' and list imagen-3.0-capability-001 and -002, the editing models, as discontinued endpoints with a June 30, 2026 service-disruption warning and replacement gemini-2.5-flash-image. The summary should say these Imagen editing parameters describe endpoints the Vertex page lists under "Discontinued endpoints", with a June 30, 2026 migration deadline in its caution box (the capability models' own discontinuation date lines were not read), not a current option. The OpenAI, Ideogram, and mask-format claims were re-read and still match (OpenAI guide now names gpt-image-2.5-sunburst and -flare; Ideogram 4.5 and 3.0 mask text unchanged); the Midjourney editor page returned HTTP 403 and was not rechecked. · locator: curator correction paragraph in this record body (C3-B977-02) · source: https://platform.openai.com/docs/guides/image-generation.md
- [sourced_fact] SUPERSEDED IN PART 2026-10-24 by curator correction C3-B977-02 (see the correction claim above); original kept for history: Mask formats are not interchangeable: OpenAI needs a same-size mask with an alpha channel and calls masking prompt-based (the model may not follow the exact shape); Ideogram uses black for the area to edit and white to keep, with a same-size mask that must contain both; Imagen takes a black-and-white mask or automatic background, foreground or semantic masks with a dilation setting and a sampling-step knob; Midjourney's editor now routes inpainting through the V8.X Edit Model. Ideogram 4.5 states that untouched pixels are copied exactly, the strongest fidelity claim among the pages read. · locator: candidate evidence excerpts · source: https://platform.openai.com/docs/guides/image-generation.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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