The Images API from LLM Gateway — 2 operation(s) for images.
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openapi: 3.2.0
info:
version: 1.0.0
title: LLM Gateway Images API
description: 'OpenAI-compatible LLM gateway: chat completions, embeddings, images, audio, video, moderation, OCR, rerank, web search and typed decisions across providers with one API key.'
servers:
- url: https://api.llmgateway.io
- url: http://localhost:4001
tags:
- name: Images
paths:
/v1/images/generations:
post:
operationId: v1_images_generations
summary: Create image
description: Creates an image given a prompt. Internally routes to a chat completions model with image generation capabilities.
security:
- bearerAuth: []
requestBody:
content:
application/json:
schema:
type: object
properties:
prompt:
type: string
minLength: 1
description: A text description of the desired image(s).
example: A white siamese cat
model:
type: string
default: auto
description: The model to use for image generation. Defaults to auto which selects an appropriate image generation model.
example: gemini-3.1-flash-image
n:
type: integer
minimum: 1
maximum: 10
default: 1
description: The number of images to generate. Must be between 1 and 10.
example: 1
size:
type: string
description: The size of the generated images. Supported sizes depend on the model and provider.
example: 1024x1024
quality:
type: string
enum:
- standard
- hd
- low
- medium
- high
- xhigh
- max
- auto
description: The quality of the image that will be generated. Supported values depend on the model and provider.
example: standard
response_format:
type: string
enum:
- b64_json
default: b64_json
description: The format in which the generated images are returned. Only b64_json is supported since images are generated via chat completions models.
example: b64_json
style:
type: string
enum:
- vivid
- natural
description: The style of the generated images.
example: vivid
aspect_ratio:
type: string
description: The aspect ratio of the generated images (e.g. '1:1', '16:9', '4:3', '5:4'). Takes precedence over size if both are provided.
example: '16:9'
moderation:
type: string
enum:
- auto
- low
description: Content moderation strictness for models that support it (GPT Image). 'auto' applies the default filtering, 'low' is less restrictive. Ignored by models without a moderation control.
example: low
service_tier:
type: string
enum:
- auto
- default
- flex
- priority
description: Processing tier for the request, forwarded to the underlying chat completion. `flex` and `priority` are only accepted for provider/model mappings that support the tier; an unsupported tier returns a 400 `unsupported_service_tier` error.
example: flex
required:
- prompt
responses:
'200':
description: Image generation response.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
content:
application/json:
schema:
type: object
properties:
created:
type: number
data:
type: array
items:
type: object
properties:
b64_json:
type: string
revised_prompt:
type: string
required:
- b64_json
usage:
type: object
properties:
input_tokens:
type: number
input_tokens_details:
type: object
properties:
image_tokens:
type: number
text_tokens:
type: number
required:
- image_tokens
- text_tokens
output_tokens:
type: number
output_tokens_details:
type: object
properties:
image_tokens:
type: number
text_tokens:
type: number
required:
- image_tokens
- text_tokens
total_tokens:
type: number
cost:
type:
- number
- 'null'
description: Total cost of the request in USD.
cost_details:
type: object
additionalProperties:
type:
- number
- 'null'
description: Cost breakdown in USD, matching `usage.cost_details` on chat completions.
required:
- input_tokens
- input_tokens_details
- output_tokens
- output_tokens_details
- total_tokens
description: Token usage and cost of the underlying generation.
required:
- created
- data
'400':
description: Invalid request body or parameters.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'401':
description: Missing or invalid API key.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'402':
description: Insufficient credits or plan limits reached.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'403':
description: Forbidden request or upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'404':
description: Unknown model or upstream not-found response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'408':
description: Request timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'410':
description: Archived or unavailable project.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'413':
description: Request too large.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'415':
description: Unsupported media type.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'429':
description: Rate limited. Response headers describe only LLMGateway-enforced limits; upstream provider headers are not forwarded. Honor Retry-After when present.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'500':
description: Internal server error.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'502':
description: Failed to connect to the upstream provider.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'503':
description: Service unavailable upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'504':
description: Upstream provider timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'529':
description: Gateway overloaded.
headers:
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
tags:
- Images
/v1/images/edits:
post:
operationId: v1_images_edits
summary: Edit image
description: Creates an edited image from one or more source images and a prompt.
security:
- bearerAuth: []
requestBody:
content:
application/json:
schema:
type: object
properties:
images:
type: array
items:
type: object
properties:
image_url:
type: string
description: A fully qualified HTTPS URL or base64-encoded data URL.
example: https://example.com/source-image.png
required:
- image_url
minItems: 1
maxItems: 16
description: Input image references to edit. Provide image_url as HTTPS URL or data URL.
prompt:
type: string
minLength: 1
description: A text description of the desired image edit.
example: Add a watercolor effect to this image
background:
type: string
enum:
- transparent
- opaque
- auto
description: Background behavior for generated image output.
example: transparent
input_fidelity:
type: string
enum:
- high
- low
description: Controls fidelity to the original input image(s).
example: high
model:
type: string
description: The model to use for image editing.
example: gemini-3-pro-image
n:
type: integer
minimum: 1
maximum: 10
description: The number of edited images to generate.
example: 1
output_compression:
type: integer
minimum: 0
maximum: 100
description: Compression level for jpeg or webp output.
example: 100
output_format:
type: string
enum:
- png
- jpeg
- webp
description: Output image format.
example: png
quality:
type: string
enum:
- low
- medium
- high
- xhigh
- max
- auto
description: Output quality for image models.
example: high
size:
type: string
description: Requested output image size. Supported values depend on the model and provider.
example: 1024x1024
aspect_ratio:
type: string
description: The aspect ratio of the edited images (e.g. '1:1', '16:9', '4:3', '5:4'). Takes precedence over size-derived defaults.
example: '16:9'
moderation:
type: string
enum:
- auto
- low
description: Content moderation strictness for models that support it (GPT Image). 'auto' applies the default filtering, 'low' is less restrictive. Ignored by models without a moderation control.
example: low
service_tier:
type: string
enum:
- auto
- default
- flex
- priority
description: Processing tier for the request, forwarded to the underlying chat completion. `flex` and `priority` are only accepted for provider/model mappings that support the tier; an unsupported tier returns a 400 `unsupported_service_tier` error.
example: flex
required:
- images
- prompt
responses:
'200':
description: Image edit response.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
content:
application/json:
schema:
type: object
properties:
created:
type: number
data:
type: array
items:
type: object
properties:
b64_json:
type: string
revised_prompt:
type: string
required:
- b64_json
usage:
type: object
properties:
input_tokens:
type: number
input_tokens_details:
type: object
properties:
image_tokens:
type: number
text_tokens:
type: number
required:
- image_tokens
- text_tokens
output_tokens:
type: number
output_tokens_details:
type: object
properties:
image_tokens:
type: number
text_tokens:
type: number
required:
- image_tokens
- text_tokens
total_tokens:
type: number
cost:
type:
- number
- 'null'
description: Total cost of the request in USD.
cost_details:
type: object
additionalProperties:
type:
- number
- 'null'
description: Cost breakdown in USD, matching `usage.cost_details` on chat completions.
required:
- input_tokens
- input_tokens_details
- output_tokens
- output_tokens_details
- total_tokens
description: Token usage and cost of the underlying generation.
background:
type: string
enum:
- transparent
- opaque
output_format:
type: string
enum:
- png
- webp
- jpeg
quality:
type: string
enum:
- low
- medium
- high
- xhigh
- max
size:
type: string
required:
- created
- data
'400':
description: Invalid request body or parameters.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'401':
description: Missing or invalid API key.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'402':
description: Insufficient credits or plan limits reached.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'403':
description: Forbidden request or upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'404':
description: Unknown model or upstream not-found response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'408':
description: Request timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'410':
description: Archived or unavailable project.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'413':
description: Request too large.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'415':
description: Unsupported media type.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'429':
description: Rate limited. Response headers describe only LLMGateway-enforced limits; upstream provider headers are not forwarded. Honor Retry-After when present.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'500':
description: Internal server error.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'502':
description: Failed to connect to the upstream provider.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'503':
description: Service unavailable upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'504':
description: Upstream provider timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'529':
description: Gateway overloaded.
headers:
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
tags:
- Images
components:
schemas:
OpenAIError:
type: object
properties:
error:
type: object
properties:
message:
type: string
type:
type: string
param:
type:
- string
- 'null'
code:
type:
- string
- 'null'
required:
- message
- type
- param
- code
required:
- error
description: OpenAI-compatible error object.
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: Bearer token authentication using API keys
externalDocs:
url: https://docs.llmgateway.io
description: LLMGateway Documentation