# For a first image request, which size/aspect, count and prompt-rewriting controls do Midjourney, OpenAI, Imagen on Vertex AI, Ideogram and Adobe document, and which defaults change my prompt before generation?

- id: art_01M5MC0S9ZFC6C59PQRV5E7N2K
- 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: 2026-10-24T22:31:22.998Z
- url: https://veyrul.com/articles/art_01M5MC0S9ZFC6C59PQRV5E7N2K

Corrected 2026-10-24 - see C3-B1034-01; the original statements below are kept for history and are superseded where the correction says so. Corrected 2026-10-24 - see CUR-0644-01; the original statements below are kept for history and are superseded where the correction says so. All four vendors with machine-readable docs publish aspect/size controls, but with different vocabularies: Midjourney --ar, Imagen enumerated ratios (1:1, 3:4, 4:3, 9:16, 16:9), OpenAI free-form WxH within bounds, Ideogram resolution/aspect enums. Three of them document automatic prompt rewriting that is on by default (Imagen enhancePrompt true, Ideogram magic_prompt auto, OpenAI Responses image tool revises the prompt), so the prompt sent is not necessarily the prompt rendered. Midjourney instead exposes two creativity sliders, stylize (default 100, 0-1000) and chaos (default 0, 0-100). Adobe's per-control pages were not read for this candidate (see not_verified).

All four vendors with machine-readable docs publish aspect/size controls, but with different vocabularies: Midjourney --ar, Imagen enumerated ratios (1:1, 3:4, 4:3, 9:16, 16:9), OpenAI free-form WxH within bounds, Ideogram resolution/aspect enums. Three of them document automatic prompt rewriting that is on by default (Imagen enhancePrompt true, Ideogram magic_prompt auto, OpenAI Responses image tool revises the prompt), so the prompt sent is not necessarily the prompt rendered. Midjourney instead exposes two creativity sliders, stylize (default 100, 0-1000) and chaos (default 0, 0-100). Adobe's per-control pages were not read for this candidate (see not_verified).

Curator correction 2026-10-24 (curator source re-verification record CUR-0644-01; sources re-fetched 2026-10-24, excerpts re-located by curator GET): The Imagen models named above have been shut down in the Gemini API: imagen-4.0-generate-001, imagen-4.0-ultra-generate-001 and imagen-4.0-fast-generate-001 on August 17, 2026, and imagen-3.0-generate-002 on November 10, 2025, with gemini-nano-banana-2.1 named as the replacement (Gemini API deprecations page, https://ai.google.dev/gemini-api/docs/deprecations.md.txt, curator GET 2026-10-24T06:35:50Z, sha256 3342ebac18090931abc3a2f58e42a07f2f1f4c7f411dc6587c4faf64831c4601). Treat the Imagen aspect-ratio and enhancePrompt statements as historical; check the replacement model's documented controls before relying on them.

Curator correction 2026-10-24 (discovery audit record C3-B1034-01, curator-reviewed C3R-0686; excerpts re-located by independent curator GET 2026-10-24): Correction. C3-B046-G16-01 (observed 2026-10-22) said the Imagen 4 pages carry a discontinuation date of June 30, 2026 and 'remain online at the observation time', advising only a check of the replacement; that was accurate as of 2026-10-22 for the model page it read, but as of 2026-10-24 the Vertex model-versions page lists Imagen 4 as retired, so Imagen on Vertex AI is no longer a current option. At 2026-10-24 the Vertex model-versions page read for this correction lists imagen-4.0-generate-001 and imagen-4.0-ultra-generate-001 under 'Retired models' with retirement date June 30, 2026 and recommended upgrade gemini-2.5-flash-image. The Imagen 4 model page still shows only the older announcement wording (discontinuation date June 30, 2026; recommendation to migrate before it), so the two pages differ in wording and both are kept; inference: the lifecycle table is the stronger statement of status, because it lists the models under 'Retired models' with a 'Retirement date'; neither page, as read, says in so many words that the endpoints have stopped serving. The Imagen parameters in G16-01 (five aspect ratios, enhancePrompt default true, up to 4 images) were accurate for those endpoints while they were available, but should not be offered as a current first-request path. Scope: imagen-4.0-fast-generate-001 does not appear in the retired table on the page read (search term 'imagen-4.0-fast'); its model-page entry carries the same discontinuation date, and no API call was made to test whether the endpoints stopped serving. The OpenAI and Ideogram prompt-rewriting and size claims in G16-01 were re-read and still match the current pages.

Curator qualifications: All excerpts located; size/aspect vocabularies differ by vendor.

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://docs.cloud.google.com/vertex-ai/generative-ai/docs/image/generate-images",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.midjourney.com/hc/en-us/articles/32859204029709-Parameter-List",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://developer.ideogram.ai/v2/api-reference/images/generate/ideogram-3.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://developer.ideogram.ai/v2/api-reference/images/generate/ideogram-4-5.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.midjourney.com/hc/en-us/articles/32196176868109-Stylize",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.midjourney.com/hc/en-us/articles/32099348346765-Chaos-Variety",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://docs.cloud.google.com/vertex-ai/generative-ai/docs/models/imagen/4-0-generate",
      "note": "candidate evidence excerpts"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Curator correction 2026-10-24 (curator source re-verification record CUR-0644-01; sources re-fetched 2026-10-24, excerpts re-located by curator GET): The Imagen models named above have been shut down in the Gemini API: imagen-4.0-generate-001, imagen-4.0-ultra-generate-001 and imagen-4.0-fast-generate-001 on August 17, 2026, and imagen-3.0-generate-002 on November 10, 2025, with gemini-nano-banana-2.1 named as the replacement (Gemini API deprecations page, https://ai.google.dev/gemini-api/docs/deprecations.md.txt, curator GET 2026-10-24T06:35:50Z, sha256 3342ebac18090931abc3a2f58e42a07f2f1f4c7f411dc6587c4faf64831c4601). Treat the Imagen aspect-ratio and enhancePrompt statements as historical; check the replacement model's documented controls before relying on them. · locator: curator correction paragraph in this record body (C3-B1034-01, CUR-0644-01) · source: https://platform.openai.com/docs/guides/image-generation.md
- [sourced_fact] Curator correction 2026-10-24 (discovery audit record C3-B1034-01, curator-reviewed C3R-0686; excerpts re-located by independent curator GET 2026-10-24): Correction. C3-B046-G16-01 (observed 2026-10-22) said the Imagen 4 pages carry a discontinuation date of June 30, 2026 and 'remain online at the observation time', advising only a check of the replacement; that was accurate as of 2026-10-22 for the model page it read, but as of 2026-10-24 the Vertex model-versions page lists Imagen 4 as retired, so Imagen on Vertex AI is no longer a current option. At 2026-10-24 the Vertex model-versions page read for this correction lists imagen-4.0-generate-001 and imagen-4.0-ultra-generate-001 under 'Retired models' with retirement date June 30, 2026 and recommended upgrade gemini-2.5-flash-image. The Imagen 4 model page still shows only the older announcement wording (discontinuation date June 30, 2026; recommendation to migrate before it), so the two pages differ in wording and both are kept; inference: the lifecycle table is the stronger statement of status, because it lists the models under 'Retired models' with a 'Retirement date'; neither page, as read, says in so many words that the endpoints have stopped serving. The Imagen parameters in G16-01 (five aspect ratios, enhancePrompt default true, up to 4 images) were accurate for those endpoints while they were available, but should not be offered as a current first-request path. Scope: imagen-4.0-fast-generate-001 does not appear in the retired table on the page read (search term 'imagen-4.0-fast'); its model-page entry carries the same discontinuation date, and no API call was made to test whether the endpoints stopped serving. The OpenAI and Ideogram prompt-rewriting and size claims in G16-01 were re-read and still match the current pages. · locator: curator correction paragraph in this record body (C3-B1034-01, CUR-0644-01) · source: https://platform.openai.com/docs/guides/image-generation.md
- [sourced_fact] SUPERSEDED IN PART 2026-10-24 by curator correction C3-B1034-01, CUR-0644-01 (see the correction claim above); original kept for history: All four vendors with machine-readable docs publish aspect/size controls, but with different vocabularies: Midjourney --ar, Imagen enumerated ratios (1:1, 3:4, 4:3, 9:16, 16:9), OpenAI free-form WxH within bounds, Ideogram resolution/aspect enums. Three of them document automatic prompt rewriting that is on by default (Imagen enhancePrompt true, Ideogram magic_prompt auto, OpenAI Responses image tool revises the prompt), so the prompt sent is not necessarily the prompt rendered. Midjourney instead exposes two creativity sliders, stylize (default 100, 0-1000) and chaos (default 0, 0-100). Adobe's per-control pages were not read for this candidate (see not_verified). · 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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