Documentation Index
Fetch the complete documentation index at: https://docs.gmicloud.ai/llms.txt
Use this file to discover all available pages before exploring further.
Model ID
gemini-3.1-flash-image-preview
Gemini 3.1 Flash Image Preview API Usage Guide
Overview
Gemini 3.1 Flash Image Preview is optimized for image understanding and generation, balancing speed and cost. It supports text-to-image, image-guided editing, and multi-turn iterative workflows via contents.
Reference: https://docs.cloud.google.com/vertex-ai/generative-ai/docs/models/gemini/3-1-flash-image
Authentication
All API requests require authentication using an API key. Include your API key in the Authorization header:
Authorization: Bearer YOUR_API_KEY
Submit Image Generation Request
Base URL
https://console.gmicloud.ai
Endpoint
POST /api/v1/ie/requestqueue/apikey/requests
curl -X POST "https://console.gmicloud.ai/api/v1/ie/requestqueue/apikey/requests" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "gemini-3.1-flash-image-preview",
"payload": {
"prompt": "A hyperrealistic portrait of a cyberpunk woman under neon lights",
"image": [
"https://example.com/ref1.jpg",
"https://example.com/ref2.jpg"
],
"image_size": "1K",
"aspect_ratio": "4:5"
}
}'
Request Parameters
| Parameter | Type | Required | Description | Default | Constraints |
|---|
prompt | string | Yes (single-turn) | Text description of the target image. | - | Required when contents is not provided |
image | string/array | No | Optional reference image URLs for image-guided generation/editing. | - | Max 14 images; PNG/JPEG/WebP/HEIC/HEIF; 7MB inline upload, 30MB via GCS |
image_size | string | No | Output resolution preset for generated image. | ”1K” | Options: “512”, “1K”, “2K”, “4K” |
aspect_ratio | string | No | Aspect ratio of the generated image. | ”1:1” | Options: “1:1”, “3:2”, “2:3”, “3:4”, “4:3”, “4:5”, “5:4”, “9:16”, “16:9”, “21:9” |
image_output_format | string | No | Output image format. | ”png” | Options: “png”, “jpeg” |
contents | array | No | Multi-turn conversation payload for iterative editing. | - | When provided, prompt and image are ignored |
Response
{
"request_id": "7eaa77fc-bc67-4021-9f1b-96b3fd832314",
"model": "gemini-3.1-flash-image-preview",
"status": "queued",
"created_at": 1761763441,
"updated_at": 1761763441,
"queued_at": 1761763441
}
Check Request Status
Endpoint
GET /api/v1/ie/requestqueue/apikey/requests/{request_id}
Example
curl -X GET "https://console.gmicloud.ai/api/v1/ie/requestqueue/apikey/requests/7eaa77fc-bc67-4021-9f1b-96b3fd832314" \
-H "Authorization: Bearer YOUR_API_KEY"
Response
{
"request_id": "7eaa77fc-bc67-4021-9f1b-96b3fd832314",
"model": "gemini-3.1-flash-image-preview",
"status": "success",
"payload": {
"prompt": "A hyperrealistic portrait of a cyberpunk woman under neon lights",
"image": [
"https://example.com/ref1.jpg",
"https://example.com/ref2.jpg"
],
"image_size": "1K",
"aspect_ratio": "4:5"
},
"outcome": {
"media_urls": [
{
"id": "0",
"url": "https://storage.googleapis.com/gmi-generated-assets/.../gemini_output_0.png"
}
]
},
"created_at": 1761763441,
"updated_at": 1761763451,
"queued_at": 1761763441
}
Request Status Values
| Status | Description |
|---|
queued | Request is waiting to be processed |
processing | Image generation is in progress |
success | Image generation completed successfully |
failed | Image generation failed |
cancelled | Request was cancelled |
List Your Requests
Endpoint
GET /api/v1/ie/requestqueue/apikey/requests?model_id=gemini-3.1-flash-image-preview
Example
curl -X GET "https://console.gmicloud.ai/api/v1/ie/requestqueue/apikey/requests?model_id=gemini-3.1-flash-image-preview" \
-H "Authorization: Bearer YOUR_API_KEY"
Endpoint
GET /api/v1/ie/requestqueue/apikey/models/gemini-3.1-flash-image-preview
Example
curl -X GET "https://console.gmicloud.ai/api/v1/ie/requestqueue/apikey/models/gemini-3.1-flash-image-preview" \
-H "Authorization: Bearer YOUR_API_KEY"
List Available Models
Endpoint
GET /api/v1/apikey/models
Example
curl -X GET "https://console.gmicloud.ai/api/v1/apikey/models" \
-H "Authorization: Bearer YOUR_API_KEY"
Multi-turn Conversation (Iterative Image Editing)
This model supports multi-turn conversations for iterative image editing. After generating an image, you can continue refining it by providing additional instructions.
How It Works
- First Turn: Send a regular request with
prompt (and optional image)
- Response: The response includes
next_turn_contents with prior conversation context
- Next Turn: Copy
next_turn_contents into payload contents, then append your new user instruction
- Repeat: Continue until the result is satisfactory
Model Specifications
| Specification | Value |
|---|
| Model ID | gemini-3.1-flash-image-preview |
| Max input tokens | 131,072 |
| Max output tokens | 32,768 |
| Max input images | 14 |
| Max file size (inline upload) | 7 MB |
| Max file size (GCS) | 30 MB |
| Max input size | 500 MB |
| Supported image MIME types | image/png, image/jpeg, image/webp, image/heic, image/heif |
| Supported aspect ratios | 1:1, 3:2, 2:3, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9 |
| Temperature | 0.0-2.0 (default 1.0) |
| topP | 0.0-1.0 (default 0.95) |
| candidateCount | 1 |
Capabilities
- Supported: System instructions, Count Tokens, Thinking
- Not supported: Code execution, Function calling, Gemini Live API, implicit/explicit context caching, Vertex AI RAG Engine, Chat completions
Tips for Better Results
- Use specific and descriptive prompts for stable outputs.
- For complex edits, use multi-turn mode with
contents for iterative refinement.
