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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:

engineBest forNotes
sdcpp (ecosystem sd1)Default — Stable Diffusion C++ on Civitai workerssampleMethod + schedule sdcpp enums, textual-inversion embeddings, uCache mode.
comfy (ecosystem sd1)When you specifically need ComfyUI sampler/scheduler enums or a Comfy-only featuresampler + scheduler Comfy enums, denoiseStrength (vs sdcpp's strength) on variants.

Default choice: 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 ​

sdcpp (default path) ​

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": "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)
Valid JSON

Common sdcpp-sd1 parameters:

FieldDefaultRangeNotes
model— ✅AIR URNSD1 checkpoint. See the catalog.
prompt— ✅≤ 10 000 charsBooru-style tags work best. Lead with quality tags (masterpiece, best quality, …).
negativePrompt(none)≤ 10 000 charsStrongly recommended on SD1 — worst quality, low quality, blurry, bad anatomy, bad hands is a solid starting point.
width / height51264–2048, divisible by 16SD1's native resolution is 512×512. Aspect-ratio variants like 512×768 or 768×512 work; going much bigger often produces duplicated subjects.
cfgScale70–306–8 is the sweet spot for SD1.
steps201–15020–30 typical; 30+ rarely helps.
sampleMethodeulerenumSdCppSampleMethod.
schedulediscreteenumSdCppSchedule.
clipSkip-1int-1 = model default. 2 is a common hand-tuned value on many SD1 checkpoints — try it if output feels stiff.
vaeModel(checkpoint VAE)AIR URNOverride baked-in VAE. Rarely needed.
loras{}{ airUrn: strength }Stack multiple; 0.6–1.0 strengths typical.
embeddings[]array of AIR URNsTextual inversions. Reference them in the prompt / negative prompt by their embedding name.
quantity11–12Number of images per call.
seedrandomint64Pin for reproducibility.
uCache(default)enumSdCppUCacheMode. 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.

json
{
  "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)
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.

json
{
  "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)
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.

json
{
  "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)
Valid JSON

Key differences from sdcpp:

Fieldsdcppcomfy
SamplersampleMethod (SdCppSampleMethod)sampler (ComfySampler)
Scheduleschedule (SdCppSchedule)scheduler (ComfyScheduler)
Img2img strengthstrength (default 0.7)denoiseStrength (default 0.75)
Default steps2030
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 ​

Standard imageGen output: an images[] array, one entry per quantity (shape and URL expiry).

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 ​

Preview the exact charge with whatif=true (Payments (Buzz)).

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

total = base × (width × height / referencePixels) × (steps / referenceSteps) × quantity
PathbasereferencePixelsreferenceStepsDefaults → Buzz
sdcpp + sd14512²20512²/steps: 20/q: 1 → ~4 Buzz
comfy + sd14512²30512²/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 ​

Timeouts, moderation blocks and expired blob URLs: see Common troubleshooting.

SymptomLikely causeFix
400 with "model must match AIR pattern"Passed a bare model ID or version slugUse a full AIR URN: urn:air:sd1:checkpoint:civitai:<modelId>@<versionId>.
400 with unknown propertyField 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 anatomyDimensions too far from SD1's native 512×512Generate at 512 / 768 max; upscale with imageUpscaler if you need more resolution.
Output looks flat / low-contrast on SD1clipSkip at model default where the checkpoint expects 2Try clipSkip: 2 — the convention for many SD1 community checkpoints.
Prompts feel ignored on SD1Missing quality boosters, or cfgScale too lowLead the prompt with masterpiece, best quality, … tags; bump cfgScale toward 8.
LoRA has no visible effectWrong AIR URN, model private / not published, or ecosystem mismatchVerify the URN on the LoRA's Civitai page; only SD1-tagged LoRAs work on the sd1 ecosystem.

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