SD1 image generation

SD1 is Stable Diffusion 1.x — the original open-weights family. Mature ecosystem, huge model catalog, native resolution 512×512, prompt style is Booru-like tag-soup plus quality boosters (masterpiece, best quality, …). Two invocation paths on the orchestrator:

engine	Best for	Notes
sdcpp (ecosystem sd1)	Default — Stable Diffusion C++ on Civitai workers	sampleMethod + schedule sdcpp enums, textual-inversion embeddings, uCache mode.
comfy (ecosystem sd1)	When you specifically need ComfyUI sampler/scheduler enums or a Comfy-only feature	sampler + scheduler Comfy enums, denoiseStrength (vs sdcpp's strength) on variants.

Default choice for new integrations: engine: "sdcpp", ecosystem: "sd1". Reach for comfy only when you specifically need a ComfyUI-exclusive sampler.

Both engines support createImage and createVariant (img2img). Neither supports editImage — use Flux 1 Kontext or Flux 2 Klein if you need prompt-driven editing.

Prerequisites

• A Civitai orchestration token (Quick start → Prerequisites)
• An SD1 checkpoint AIR URN — browse the Civitai SD1.5 catalog
• For createVariant: a source image URL

sdcpp (default path)

Text-to-image

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": "sd1",
      "operation": "createImage",
      "model": "urn:air:sd1:checkpoint:civitai:4384@128713",
      "prompt": "masterpiece, best quality, 1girl, solo, portrait, looking at viewer, cinematic lighting",
      "negativePrompt": "worst quality, low quality, blurry, bad anatomy",
      "width": 512,
      "height": 512,
      "cfgScale": 7,
      "steps": 20,
      "clipSkip": -1
    }
  }]
}

POST/v2/consumer/workflows

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)

{ "steps": [ { "$type": "imageGen", "input": { "engine": "sdcpp", "ecosystem": "sd1", "operation": "createImage", "model": "urn:air:sd1:checkpoint:civitai:4384@128713", "prompt": "masterpiece, best quality, 1girl, solo, portrait, looking at viewer, cinematic lighting", "negativePrompt": "worst quality, low quality, blurry, bad anatomy", "width": 512, "height": 512, "cfgScale": 7, "steps": 20, "clipSkip": -1 } } ] }

Valid JSON

Common sdcpp-sd1 parameters:

Field	Default	Range	Notes
model	— ✅	AIR URN	SD1 checkpoint. See the catalog.
prompt	— ✅	≤ 10 000 chars	Booru-style tags work best. Lead with quality tags (masterpiece, best quality, …).
negativePrompt	(none)	≤ 10 000 chars	Strongly recommended on SD1 — worst quality, low quality, blurry, bad anatomy, bad hands is a solid starting point.
width / height	512	64–2048, divisible by 16	SD1's native resolution is 512×512. Aspect-ratio variants like 512×768 or 768×512 work; going much bigger often produces duplicated subjects.
cfgScale	7	0–30	6–8 is the sweet spot for SD1.
steps	20	1–150	20–30 typical; 30+ rarely helps.
sampleMethod	euler	enum	SdCppSampleMethod.
schedule	discrete	enum	SdCppSchedule.
clipSkip	-1	int	-1 = model default. 2 is a common hand-tuned value on many SD1 checkpoints — try it if output feels stiff.
vaeModel	(checkpoint VAE)	AIR URN	Override baked-in VAE. Rarely needed.
loras	{}	{ airUrn: strength }	Stack multiple; 0.6–1.0 strengths typical.
embeddings	[]	array of AIR URNs	Textual inversions. Reference them in the prompt / negative prompt by their embedding name.
quantity	1	1–12	Number of images per call.
seed	random	int64	Pin for reproducibility.
uCache	(default)	enum	SdCppUCacheMode. Caching strategy; leave default unless you know you want otherwise.

With LoRAs

LoRAs are a map of AIR URN → strength. Style LoRAs usually want 0.6–1.0; character / concept LoRAs often sit higher.

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "sd1",
      "operation": "createImage",
      "model": "urn:air:sd1:checkpoint:civitai:4384@128713",
      "prompt": "masterpiece, best quality, cyberpunk street at night, neon signs",
      "negativePrompt": "worst quality, low quality, blurry",
      "width": 512,
      "height": 768,
      "cfgScale": 7,
      "steps": 25,
      "loras": {
        "urn:air:sd1:lora:civitai:123456@789012": 0.8
      }
    }
  }]
}

POST/v2/consumer/workflows

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)

{ "steps": [ { "$type": "imageGen", "input": { "engine": "sdcpp", "ecosystem": "sd1", "operation": "createImage", "model": "urn:air:sd1:checkpoint:civitai:4384@128713", "prompt": "masterpiece, best quality, cyberpunk street at night, neon signs", "negativePrompt": "worst quality, low quality, blurry", "width": 512, "height": 768, "cfgScale": 7, "steps": 25, "loras": { "urn:air:sd1:lora:civitai:123456@789012": 0.8 }, "clipSkip": -1 } } ] }

Valid JSON

Image-to-image (createVariant)

Pass a source image + 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 sweet spot.

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "sdcpp",
      "ecosystem": "sd1",
      "operation": "createVariant",
      "model": "urn:air:sd1:checkpoint:civitai:4384@128713",
      "prompt": "masterpiece, best quality, daytime with clear blue sky",
      "negativePrompt": "worst quality, low quality",
      "width": 512,
      "height": 512,
      "cfgScale": 7,
      "steps": 20,
      "image": "https://image.civitai.com/.../source.jpeg",
      "strength": 0.7
    }
  }]
}

POST/v2/consumer/workflows

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)

{ "steps": [ { "$type": "imageGen", "input": { "engine": "sdcpp", "ecosystem": "sd1", "operation": "createVariant", "model": "urn:air:sd1:checkpoint:civitai:4384@128713", "prompt": "masterpiece, best quality, daytime with clear blue sky", "negativePrompt": "worst quality, low quality", "width": 512, "height": 512, "cfgScale": 7, "steps": 20, "image": "https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/dd4b4ad5-040f-4f0e-baa3-6e1ff00add65/original=true,quality=90,optimized=true/26781018.jpeg", "strength": 0.7 } } ] }

Valid JSON

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

Comfy (alternative path)

Use engine: "comfy" when you specifically need a ComfyUI sampler/scheduler enum that sdcpp doesn't expose.

{
  "steps": [{
    "$type": "imageGen",
    "input": {
      "engine": "comfy",
      "ecosystem": "sd1",
      "operation": "createImage",
      "model": "urn:air:sd1:checkpoint:civitai:4384@128713",
      "prompt": "masterpiece, best quality, 1girl, solo, portrait, looking at viewer",
      "negativePrompt": "worst quality, low quality, blurry, bad hands",
      "width": 512,
      "height": 512,
      "steps": 30,
      "cfgScale": 7,
      "sampler": "euler_ancestral",
      "scheduler": "normal",
      "clipSkip": 2
    }
  }]
}

POST/v2/consumer/workflows

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)

{ "steps": [ { "$type": "imageGen", "input": { "engine": "comfy", "ecosystem": "sd1", "operation": "createImage", "model": "urn:air:sd1:checkpoint:civitai:4384@128713", "prompt": "masterpiece, best quality, 1girl, solo, portrait, looking at viewer", "negativePrompt": "worst quality, low quality, blurry, bad hands", "width": 512, "height": 512, "steps": 30, "cfgScale": 7, "sampler": "euler_ancestral", "scheduler": "normal", "clipSkip": 2 } } ] }

Valid JSON

Key differences from sdcpp:

Field	sdcpp	comfy
Sampler	sampleMethod (SdCppSampleMethod)	sampler (ComfySampler)
Schedule	schedule (SdCppSchedule)	scheduler (ComfyScheduler)
Img2img strength	strength (default 0.7)	denoiseStrength (default 0.75)
Default steps	20	30
Default clipSkip	-1 (model default)	2
embeddings array	✅	—
uCache	✅	—

Comfy also supports createVariant with image (plain string URL) + denoiseStrength; see the ComfySd1VariantImageGenInput schema.

Reading the result

Both engines emit the standard imageGen output — an images[] array, one entry per quantity:

{
  "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

SD1 at 512×512 is one of the fastest image-gen paths available — typical wall time 3–10 s per image (sdcpp) or 5–15 s (comfy, slightly heavier). wait=60 works comfortably for quantity ≤ 4. Going beyond 768px on either axis compounds runtime quadratically; submit with wait=0 and poll for large batches or dimensions.

Cost

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

Both engines use the same per-pixel / per-step shape — different reference values:

total = base × (width × height / referencePixels) × (steps / referenceSteps) × quantity

Path	base	referencePixels	referenceSteps	Defaults → Buzz
sdcpp + sd1	4	512²	20	512²/steps: 20/q: 1 → ~4 Buzz
comfy + sd1	4	512²	30	512²/steps: 30/q: 1 → ~4 Buzz

Examples:

• 512² at quantity: 4 → ~16 Buzz
• 768×512 at steps: 25 → ~4 × 1.5 × 1.25 = ~7.5 Buzz (sdcpp)
• 512² at steps: 40 → ~8 Buzz (sdcpp)

SD1 is the cheapest per-image option Civitai exposes — native 512² defaults keep the formula at 1.0 on each axis.

Troubleshooting

Symptom	Likely cause	Fix
400 with "model must match AIR pattern"	Passed a bare model ID or version slug	Use a full AIR URN: urn:air:sd1:checkpoint:civitai:<modelId>@<versionId>.
400 with unknown property	Field not valid for this engine (e.g. sampler on sdcpp, sampleMethod on comfy, denoiseStrength on sdcpp)	Match the schema for your chosen engine — see the difference table above.
Output has duplicated subjects / Frankenstein anatomy	Dimensions too far from SD1's native 512×512	Generate at 512 / 768 max; upscale with imageUpscaler if you need more resolution.
Output looks flat / low-contrast on SD1	clipSkip at model default where the checkpoint expects 2	Try clipSkip: 2 — the convention for many SD1 community checkpoints.
Prompts feel ignored on SD1	Missing quality boosters, or cfgScale too low	Lead the prompt with masterpiece, best quality, … tags; bump cfgScale toward 8.
LoRA has no visible effect	Wrong AIR URN, model private / not published, or ecosystem mismatch	Verify the URN on the LoRA's Civitai page; only SD1-tagged LoRAs work on the sd1 ecosystem.
Request timed out (wait expired)	Large quantity, non-native dimensions	Resubmit with wait=0 and poll.
Step failed, reason = "blocked"	Prompt hit content moderation	Don't retry the same input — see Errors & retries → Step-level failures.

Related

• SubmitWorkflow — operation used by every example here
• GetWorkflow — for polling
• SDXL image generation — higher-resolution successor to SD1
• Flux 2 / Flux 1 image generation — newer open-weights families with stronger prompt adherence
• Image upscaling — chain after imageGen for higher-res output
• Prompt enhancement — LLM-rewrite a prompt before feeding it in via $ref (use ecosystem: "sd1" on the enhancer)
• Full parameter catalog: the Sd1CreateImageGenInput / Sd1VariantImageGenInput / ComfySd1CreateImageGenInput / ComfySd1VariantImageGenInput schemas in the API reference
• imageGen endpoint OpenAPI spec — standalone OpenAPI 3.1 YAML covering the full imageGen surface; import into Postman / OpenAPI Generator