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Modify an image based on a user-provided image and prompt.

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Endpoint

POST https://api.stepfun.ai/v1/images/edits

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Request parameters

  • model string required
    The model name to use. Currently supported:
    • step-image-edit-2
  • image file required
    The input image file. Currently only one image is supported.
    • step-image-edit-2: maximum input resolution 4096x4096; supports base64-encoded image input.
  • prompt string required
    Text description for the edit. Maximum length: 512 characters.
  • seed int optional
    Random seed.
    • step-image-edit-2: range [0, 2147483647]. If not provided, the server randomly generates a seed.
  • steps int optional
    Number of generation steps.
    • step-image-edit-2: range [1, 50]. Default 8.
  • cfg_scale float optional
    Classifier-free guidance scale.
    • step-image-edit-2: must be >= 1.0, range [1.0, 10.0]. Default 1.0.
  • size string optional
    • step-image-edit-2: this parameter is ignored for editing; the result image is returned at the same size as the input image.
  • negative_prompt string optional
    Negative prompt. Up to 512 characters, default "". When cfg_scale = 1.0, the current implementation does not pass the negative prompt to the underlying model.
  • text_mode bool optional
    Optimization strategy for text-rendering scenarios. Default False, enable as needed.
  • response_format string optional
    Format of the returned image. Supported: b64_json or url. Default url.

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Response

  • created int
    Timestamp of when the image was created (seconds).
  • data object array
    Array of generated image objects.
    • seed int
      The seed used during generation.
    • finish_reason string
      Reason for completion. success indicates successful generation; content_filtered indicates successful generation but stopped due to content filtering.
    • b64_json string
      Base64-encoded image. Returned when response_format is b64_json.
    • url string
      Image download URL. Returned when response_format is url. The URL has a limited validity period (currently 2 hours); download and save the image to your own storage to avoid relying on this link.

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Example

curl -X POST "https://api.stepfun.ai/v1/images/edits" \
  -H "Authorization: Bearer $STEP_API_KEY" \
  -F 'model=step-image-edit-2' \
  -F 'image=@input.webp' \
  -F 'prompt=Make the character ride a bicycle, holding a sign that says "Saudi Arabia"' \
  -F 'response_format=b64_json' \
  -F 'cfg_scale=1.0' \
  -F 'steps=8' \
  -F 'seed=1' \
  -F 'text_mode=true'