Stability AI Sketch API

openapi: 3.2.0
info:
  title: Stability AI Stable Image Control Sketch API
  description: The Stability AI Stable Image Control API provides image-to-image generation guided by structural inputs such as sketches, reference structures, and style guides. Using ControlNet-based models, developers can generate new images that follow the composition, edges, or layout of a source image while applying new styles or content based on text prompts. The API supports sketch-to-image, structure-guided generation, and style transfer workflows.
  version: v2beta
  contact:
    name: Stability AI Support
    url: https://platform.stability.ai
  termsOfService: https://stability.ai/terms-of-service
servers:
- url: https://api.stability.ai
  description: Production Server
security:
- bearerAuth: []
tags:
- name: Sketch
  description: Generate images from hand-drawn sketches or line drawings, guided by a text prompt to fill in details, colors, and textures.
paths:
  /v2beta/stable-image/control/sketch:
    post:
      operationId: controlImageSketch
      summary: Generate an image from a sketch
      description: Generates a detailed image from a hand-drawn sketch or line drawing. The sketch provides the structural composition while the text prompt guides the content, colors, textures, and style of the output image.
      tags:
      - Sketch
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/SketchControlRequest'
      responses:
        '200':
          description: Successfully generated image from sketch
          content:
            image/jpeg:
              schema:
                type: string
                format: binary
            image/png:
              schema:
                type: string
                format: binary
            image/webp:
              schema:
                type: string
                format: binary
            application/json:
              schema:
                $ref: '#/components/schemas/ControlImageResponse'
        '400':
          description: Bad request due to invalid parameters
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized due to missing or invalid API key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: Forbidden due to content moderation or insufficient permissions
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '429':
          description: Rate limit exceeded
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    SketchControlRequest:
      type: object
      required:
      - image
      - prompt
      properties:
        image:
          type: string
          format: binary
          description: The sketch or line drawing image to use as structural guidance.
        prompt:
          type: string
          maxLength: 10000
          description: Text describing the desired output image including content, colors, textures, and style.
        negative_prompt:
          type: string
          maxLength: 10000
          description: Text describing elements to exclude from the output image.
        control_strength:
          type: number
          minimum: 0
          maximum: 1
          default: 0.7
          description: Controls how closely the output follows the input sketch. Higher values produce outputs more faithful to the sketch structure.
        seed:
          type: integer
          minimum: 0
          maximum: 4294967294
          default: 0
          description: A value to control randomness in generation.
        output_format:
          type: string
          enum:
          - jpeg
          - png
          - webp
          default: png
          description: The output format of the generated image.
    ControlImageResponse:
      type: object
      properties:
        image:
          type: string
          description: Base64-encoded image data when Accept header is set to application/json.
        finish_reason:
          type: string
          enum:
          - SUCCESS
          - CONTENT_FILTERED
          description: The reason the generation finished.
        seed:
          type: integer
          description: The seed used for generation.
    ErrorResponse:
      type: object
      properties:
        id:
          type: string
          description: A unique identifier for the error instance.
        name:
          type: string
          description: The error type name.
        message:
          type: string
          description: A human-readable description of the error.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: API key authentication. Pass your Stability AI API key as a Bearer token in the Authorization header.
externalDocs:
  description: Stability AI API Documentation
  url: https://platform.stability.ai/docs/api-reference