Flux 1 image generation

Flux 1 is Black Forest Labs' original open-weights family (Dev / Schnell plus the commercial Kontext tier). The whole family is the flux1 ecosystem on the orchestrator — same checkpoint family, same AIR prefix (urn:air:flux1:…), same resource pool for workers and capability matching. What differs is how you invoke it: there's no single engine: "flux1" discriminator, so you pick one of three engine values depending on what you want:

`engine`	Best for	Notes
`sdcpp` (ecosystem `flux1`)	Default — Stable Diffusion C++ on Civitai workers	Only `diffuserModel` is required; VAE / CLIP-L / T5-XXL default to sensible components. Supports LoRAs, `createImage` / `createVariant` / `editImage`.
`comfy` (ecosystem `flux1`)	When you specifically need ComfyUI sampler knobs	Full sampler/scheduler enum control, LoRA support, checkpoint via AIR URN. Picks a heavier worker than sdcpp — reach for this only if you need a Comfy-specific sampler.
`flux1-kontext` (ecosystem `flux1`)	Image editing / prompt-based edits via BFL's managed Kontext API	`dev` / `pro` / `max` tiers; the `ecosystem` field isn't in the request body but the endpoint lives in the same ecosystem internally

Default choice for new integrations: engine: "sdcpp", ecosystem: "flux1". Sdcpp's defaults handle the component models for you, so you only need to pick a diffuser. Reach for comfy when you need a specific Comfy sampler; use flux1-kontext when you want BFL's managed editor.

If you're starting fresh and don't need Flux.1 specifically, consider Flux 2 — cleaner schema, better quality, same orchestration-side usage.

Prerequisites

A Civitai orchestration token (Quick start → Prerequisites)
A Flux.1 diffuser AIR URN (for sdcpp / comfy paths) — browse the Civitai Flux 1.D catalog
For createVariant / editImage / Kontext editing: one or more source image URLs

sdcpp (default path)

Runs Flux.1 on Civitai's sdcpp workers. Minimal required input — just pick a diffuser and write a prompt. Every other model component (VAE, CLIP-L, T5-XXL) has a working default; LoRAs, samplers, and dimensions are tunable.

Text-to-image

http

POST https://orchestration.civitai.com/v2/consumer/workflows?wait=60
Authorization: Bearer <your-token>
Content-Type: application/json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "flux1",
      "operation": "createImage",
      "diffuserModel": "urn:air:flux1:diffuser:civitai:618692@691639",
      "prompt": "A photorealistic portrait of a woman in a cyberpunk city, neon reflections",
      "width": 1024,
      "height": 1024
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Common sdcpp-flux1 parameters:

Field	Default	Range	Notes
`diffuserModel`	— ✅	AIR URN	The only required model component. A Flux.1 diffuser from the catalog.
`prompt`	— ✅	≤ 1000 chars	Natural-language descriptions work best on Flux.
`width` / `height`	`1024`	`832`–`1216`, divisible by 16	Tighter than Comfy's `64`–`2048`.
`steps`	`28`	`4`–`50`	Sampler steps. Diminishing returns past ~30.
`cfgScale`	`3.5`	`1`–`20`	Classifier-free guidance. `2.5`–`4` is the sweet spot for Flux.
`sampleMethod`	`euler`	enum	See `SdCppSampleMethod`.
`schedule`	`simple`	enum	See `SdCppSchedule`.
`negativePrompt`	(none)	string	Available — Comfy/Kontext flux1 variants don't expose one.
`loras`	`{}`	`{ airUrn: strength }`	Stack multiple; strengths in `0.0`–`2.0` are typical.
`quantity`	`1`	`1`–`4`	Number of images per call.
`seed`	random	int64	Pin for reproducibility.
`vaeModel`	(default)	AIR URN	Override the default VAE. Usually unnecessary.
`clipLModel`	(default)	AIR URN	Override the default CLIP-L.
`t5XXLModel`	(default)	AIR URN	Override the default T5-XXL text encoder.

The default component URNs (Green-Sky's quantized GGUF releases on HuggingFace) are what the orchestrator falls back to when you omit vaeModel / clipLModel / t5XXLModel. They work out of the box — override only if you need a specific quantization or cached component.

With LoRAs

LoRAs are a map of AIR URN → strength, identical shape to Comfy:

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "flux1",
      "operation": "createImage",
      "diffuserModel": "urn:air:flux1:diffuser:civitai:618692@691639",
      "prompt": "A detailed anime character in a magical forest, ethereal lighting",
      "width": 1024,
      "height": 1024,
      "loras": {
        "urn:air:flux1:lora:civitai:123456@789012": 0.8
      }
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Image-to-image (`createVariant`)

Pass a source image and a new prompt; the model re-imagines it. strength controls how much of the source to preserve — 0.0 returns the source unchanged, 1.0 discards it entirely. 0.6–0.8 is the "keep composition, change style" sweet spot.

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "flux1",
      "operation": "createVariant",
      "diffuserModel": "urn:air:flux1:diffuser:civitai:618692@691639",
      "prompt": "Make it daytime with clear blue sky",
      "width": 1024,
      "height": 1024,
      "image": "https://image.civitai.com/.../source.jpeg",
      "strength": 0.7
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Note image is a plain string URL (not a { url: ... } wrapper), and the field is strength (not denoiseStrength like on Comfy).

Edit image (`editImage`)

Alternative to createVariant — accepts up to two reference images and treats the prompt as an edit instruction rather than a variant direction:

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "flux1",
      "operation": "editImage",
      "diffuserModel": "urn:air:flux1:diffuser:civitai:618692@691639",
      "prompt": "Make it a winter scene with snow falling",
      "width": 1024,
      "height": 1024,
      "images": [
        "https://image.civitai.com/.../source.jpeg"
      ]
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

images[] takes up to 2 entries. Use createVariant when you want a strength-weighted re-imagining of a single source; use editImage when you want prompt-driven surgery (a more literal "do X to this picture" interpretation).

Comfy (ComfyUI-specific knobs)

When you need controls specific to ComfyUI's sampler surface — ComfySampler / ComfyScheduler enum values, a single-checkpoint AIR URN instead of separate components, or denoiseStrength semantics on img2img — use engine: "comfy". Otherwise prefer sdcpp.

Text-to-image

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "comfy",
      "ecosystem": "flux1",
      "operation": "createImage",
      "model": "urn:air:flux1:checkpoint:civitai:618692@691639",
      "prompt": "A photorealistic portrait of a woman in a cyberpunk city, neon reflections",
      "width": 1024,
      "height": 1024,
      "steps": 20,
      "cfgScale": 3.5,
      "sampler": "euler",
      "scheduler": "simple",
      "quantity": 1
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Key differences from sdcpp:

Field	sdcpp	comfy
Model spec	`diffuserModel` (+ optional components)	`model` — single checkpoint AIR URN
Sampler	`sampleMethod` (`SdCppSampleMethod`)	`sampler` (`ComfySampler`)
Schedule	`schedule` (`SdCppSchedule`)	`scheduler` (`ComfyScheduler`)
Img2img strength	`strength` (`createVariant`)	`denoiseStrength` (`createVariant`)
Max `quantity`	`4`	`12`
Max `width` / `height`	`1216`	`2048`
`negativePrompt`	✅	—

Comfy also supports createVariant with the same shape, using a plain image string (URL, data URL, or Base64) and denoiseStrength instead of the plain image / strength pair sdcpp uses. See the ComfyFlux1VariantImageGenInput schema for the full field list.

flux1-kontext (managed editing tier)

flux1-kontext stays inside the flux1 ecosystem — same checkpoint family, same AIR prefix for any LoRAs/models you'd reference elsewhere in the flux1 ecosystem — but routes inference to BFL's managed Kontext provider. Three model tiers (dev/pro/max), simpler input schema — just prompt + optional images[] + aspectRatio. No checkpoint selection, no LoRAs, no sampler knobs. The trade-off is convenience: BFL handles quality; you handle prompts and reference images.

Text-to-image

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "flux1-kontext",
      "model": "pro",
      "prompt": "A photograph of a cat wearing a tiny astronaut helmet",
      "quantity": 1
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Image editing (the Kontext strength)

Pass images[] to edit an existing image via prompt:

json

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "flux1-kontext",
      "model": "max",
      "prompt": "Make it daytime",
      "quantity": 1,
      "images": [
        "https://image.civitai.com/.../source.jpeg"
      ]
    }
  }]
}

Set your Civitai API token via the Token button in the navbar to enable Try It.

Request body — edit to customize (e.g. swap the image URL or prompt)

Valid JSON

Kontext models:

`model`	Notes
`dev`	Open-weights tier. Cheapest Kontext option.
`pro`	Commercial tier — BFL's standard production model. Default recommendation.
`max`	Top tier — highest quality, slowest, most expensive. Use for hero shots.

Kontext-specific parameters:

Field	Default	Notes
`prompt`	— ✅	≤ 1000 chars.
`images[]`	—	URLs, data URLs, or Base64. When present → image-edit mode. Omit → text-to-image.
`aspectRatio`	`1:1`	Enum: `21:9`, `16:9`, `4:3`, `3:2`, `1:1`, `2:3`, `3:4`, `9:16`, `9:21`.
`guidanceScale`	`3.5`	`1`–`20`.
`quantity`	`1`	`1`–`4`.
`seed`	random	int64.

Reading the result

All Flux 1 paths emit the standard imageGen output — an images[] array, one entry per quantity:

json

{
  "status": "succeeded",
  "steps": [{
    "name": "0",
    "$type": "imageGen",
    "status": "succeeded",
    "output": {
      "images": [
        { "id": "blob_...", "url": "https://.../signed.jpeg" }
      ]
    }
  }]
}

Blob URLs are signed and expire — refetch the workflow or call GetBlob for a fresh URL.

Runtime

Path	Typical wall time per 1024×1024 image	`wait` recommendation
`sdcpp + flux1`	10–30 s	`wait=60` usually fine
`comfy + flux1`	10–30 s (LoRAs add a few seconds each)	`wait=60` usually fine
`flux1-kontext` (dev / pro)	10–30 s depending on BFL queue	`wait=60` usually fine
`flux1-kontext` (max)	15–60 s	`wait=60` sometimes, fall back to `wait=0` on busy periods

quantity > 2 or large dimensions push you toward the 100-second request timeout — submit with wait=0 and poll instead.

Cost

Billed in Buzz on the workflow's transactions. Use whatif=true for an exact preview; see Payments (Buzz) for currency selection.

sdcpp path (Flux1SdCppImageGenInput.CalculateCost):

base  = 0.5 × steps × (editImages + 1) × (cfgScale == 1 ? 1 : 2)
total = base × quantity

Shape	Buzz
`createImage`, `steps: 28`, `cfgScale: 3.5`, `quantity: 1`	~28
`createImage`, `steps: 28`, `quantity: 4`	~112
`createVariant`, `quantity: 1`	~28
`editImage` with 1 reference	~56

Comfy path (ComfyFlux1ImageGenInput.CalculateCost) — per-pixel + per-step scaling:

total = 8 × (width × height / 1024²) × (steps / 20) × quantity

At 1024² / steps: 20 / quantity: 1 → ~8 Buzz. Comfy scales linearly with pixels and steps — 512² halves, 2048² quadruples, steps: 40 doubles, and so on.

Kontext (flux1-kontext, BFL-hosted) — flat per-image by tier:

Tier	Buzz per image
`dev`	~35
`pro`	~45
`max`	~90

Multiply by quantity. No per-step / per-pixel scaling since Kontext doesn't expose those knobs.

Troubleshooting

Symptom	Likely cause	Fix
`400` with unknown property	Field not valid for this `engine` (e.g. `sampler` on sdcpp, `sampleMethod` on comfy, `loras` on `flux1-kontext`)	Match the schema for your chosen engine — see the tables above.
`400` with "diffuserModel is required"	sdcpp `createImage` / `createVariant` / `editImage` without a diffuser	Supply `diffuserModel` — the only required model component on sdcpp. VAE / CLIP-L / T5-XXL default automatically.
`400` with "model must match AIR pattern"	Passed a bare model ID or version slug	Use a full AIR URN: `urn:air:flux1:diffuser:civitai:<modelId>@<versionId>` (sdcpp) or `urn:air:flux1:checkpoint:civitai:<modelId>@<versionId>` (comfy).
`400` with "width/height out of range" on sdcpp	sdcpp clamps tighter than Comfy (`832`–`1216`, divisible by 16)	Round to a valid multiple of 16 inside that range, or switch to the Comfy engine for more freedom.
Output ignores the prompt on Flux.1	`cfgScale` too low or prompt too short	Raise `cfgScale` toward 4; add lighting / composition / camera cues.
LoRA silently has no effect	Wrong AIR URN, unpublished / private model	Verify the URN on the LoRA's Civitai page; strengths outside `0.0`–`2.0` may also be clamped.
Kontext edit returns a generation unrelated to the source	`images[]` URL not reachable by BFL	Use a CDN-served URL (Civitai CDN works); see the source-URL notes in Transcription → Choosing a source URL.
Request timed out (`wait` expired)	Large `quantity`, Kontext `max` on a busy queue	Resubmit with `wait=0` and poll.
Step `failed`, `reason = "blocked"`	Prompt or input image hit content moderation	Don't retry the same input — see Errors & retries → Step-level failures.

SubmitWorkflow — operation used by every example here
GetWorkflow — for polling
Flux 2 image generation — newer Flux family with a cleaner schema, higher quality
Image upscaling — chain after imageGen for higher-res output
Prompt enhancement — LLM-rewrite a prompt before feeding it in via $ref (use ecosystem: "flux1" on the enhancer)
Results & webhooks — handling longer runs
Full parameter catalog: the Flux1SdCpp<Operation>Input, ComfyFlux1<Operation>Input, Flux1Kontext<Model>ImageGenInput schemas in the API reference
imageGen endpoint OpenAPI spec — standalone OpenAPI 3.1 YAML covering the full imageGen surface; import into Postman / OpenAPI Generator

Flux 1 image generation ​

Prerequisites ​

sdcpp (default path) ​

Text-to-image ​

With LoRAs ​

Image-to-image (createVariant) ​

Edit image (editImage) ​

Comfy (ComfyUI-specific knobs) ​

Text-to-image ​

flux1-kontext (managed editing tier) ​

Text-to-image ​

Image editing (the Kontext strength) ​

Reading the result ​

Runtime ​

Cost ​

Troubleshooting ​

Related ​

Flux 1 image generation

Prerequisites

sdcpp (default path)

Text-to-image

With LoRAs

Image-to-image (`createVariant`)

Edit image (`editImage`)

Comfy (ComfyUI-specific knobs)

Text-to-image

flux1-kontext (managed editing tier)

Text-to-image

Image editing (the Kontext strength)

Reading the result

Runtime

Cost

Troubleshooting

Related