What is the difference between Flux 2 Pro and Flux 2 Flex?

Pro is the faster, more affordable tier at 5 cents per 1k image. Flex produces higher-fidelity output at 14 cents per 1k image. Both share the same API parameters and support text_to_image and remix_image endpoints.

How does Flux 2 compare to Midjourney for photorealistic images?

Users report Flux 2 matches or beats Midjourney on photorealism and material fidelity, with the advantage that it runs through a standard API endpoint rather than a Discord bot. It has caught up on text rendering too, though Ideogram V3 still leads on small-point typography.

Does Flux 2 output resolution affect pricing?

Yes. Each variant bills per image with resolution-based pricing. For example, Flux 2 Pro costs 5 cents at 1k and 7 cents at 2k. Flux 2 Flex costs 14 cents at 1k and 24 cents at 2k. Check the RunAPI pricing page for current rates.

How does Flux 2 compare to Flux Kontext?

Flux Kontext specializes in text-guided editing and character consistency with a single input image. Flux 2 focuses on text-to-image generation and multi-source remixing with Pro/Flex quality tiers and selectable output resolution. Both are by Black Forest Labs and available through the same RunAPI key.

Is Flux 2 async or sync?

Async. The API returns a task ID immediately. Poll the task status endpoint or set a callback_url webhook to receive the completed image URL. RunAPI SDKs and the CLI handle polling automatically.

OPENCLAW + FLUX 2

OpenClaw で Flux 2 を使う。

Black Forest Labs の Flux 2 は2つの品質層を提供します——Pro は1枚あたり5セントで高速かつ手頃な生成を、Flex はより高い忠実度の出力を実現します。どちらもテキスト→画像とマルチソース remix に対応し、解像度は 1k または 2k を選べます。OpenClaw agent は、チャットで使うのと同じ RunAPI キーで呼び出します。

API キーを取得ドキュメントを読む

1つの APIキー · テキスト→画像 + remix エンドポイント · 1k / 2k 解像度

RunAPI を使って Flux 2 Pro で画像を生成します。

要件：
- https://runapi.ai/v1/text_to_image の RunAPI text_to_image エンドポイントを呼び出します
- model を "flux-2-pro-text-to-image" に設定します
- 認可には RUNAPI_API_KEY 環境変数を使用します
- 任意で output_resolution を "1k" または "2k" に、aspect_ratio で寸法を制御します
- レスポンスは非同期です——タスクが完了するまでタスクステータスエンドポイントをポーリングし、画像 URL を取得します

curl -X POST https://runapi.ai/v1/text_to_image \
  -H "Authorization: Bearer $RUNAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux-2-pro-text-to-image",
    "prompt": "a ceramic vase with dried flowers on a linen tablecloth, natural window light, 35mm film grain",
    "aspect_ratio": "3:4",
    "output_resolution": "2k"
  }'

{
  "task_id": "tsk_abc123",
  "status": "pending",
  "model": "flux-2-pro-text-to-image"
}

curlコマンドをコピーしてテスト flux-2

仕組み

OpenClaw で Flux 2 を使う3ステップ

Configure RunAPI

Set the RUNAPI_API_KEY environment variable. If you already configured RunAPI as an OpenClaw provider for chat, the same key works for Flux 2 image generation — no extra setup needed.

export RUNAPI_API_KEY=runapi_xxx

Call Flux 2

Send a POST request to the text_to_image endpoint with model set to flux-2-pro-text-to-image. Include a prompt, and optionally set aspect_ratio (1:1, 4:3, 16:9, etc.) and output_resolution (1k or 2k). For multi-source remixing, use the remix_image endpoint with source_image_urls instead.

text_to_image

Get the result

The endpoint returns a task ID. Poll the task status endpoint until the status changes to completed, then retrieve the generated image URL from the response. RunAPI SDKs and the CLI handle polling automatically.

task_id: tsk_abc123

パラメータ

Flux 2 API パラメータ

パラメータ	型	説明
`model`	`string`	Required. flux-2-pro-text-to-image, flux-2-flex-text-to-image, flux-2-pro-remix-image, or flux-2-flex-remix-image.
`prompt`	`string`	Text description of the image to generate.
`aspect_ratio`	`string`	Optional. Output aspect ratio: 1:1, 4:3, 3:4, 16:9, 9:16, 3:2, or 2:3. Remix endpoints also accept auto.
`output_resolution`	`string`	Optional. 1k (default) or 2k. Higher resolution costs more per image.
`source_image_urls`	`array`	Required for remix_image. Array of source image URLs to blend or transform.
`callback_url`	`string`	Optional. Webhook URL for async completion notification.

OpenClaw上のFlux 2とは？

Flux 2はBlack Forest Labsによる本番グレードの画像モデルで、素材の忠実度が本物の写真と見分けがつかないレベルです。マルチリファレンスコンディショニングと400万画素出力をサポートし、ファインチューニングなしにブランド一貫性のある結果を得られます。OpenClaw agentはRunAPIのtext_to_imageエンドポイントからチャットと同じAPIキーを使って呼び出します。