# Gemini 3.1 Flash Image Generation > Image Generation Generate text and image content using the Gemini-compatible `generateContent` API. For text-to-image calls, the source document notes that `generationConfig.responseModalities` must include `IMAGE` and may include `TEXT`. ## Endpoint `POST https://api.modelverse.cn/v1beta/models/gemini-3.1-flash-image:generateContent` ## Request Body ## Responses - **200** — Generated content response containing candidate text and/or inline image data. - **400** — Invalid request parameters or generation error. - **default** — Error response. ## OpenAPI Definition ```json { "openapi": "3.1.0", "x-language": "en-US", "info": { "title": "ModelVerse gemini-3.1-flash-image Image API", "version": "1.0.0", "description": "Self-contained OpenAPI 3.1 schema for the ModelVerse Gemini-compatible\n`gemini-3.1-flash-image` image generation API.\n" }, "servers": [ { "url": "https://api.modelverse.cn", "description": "ModelVerse API endpoint documented for this model." } ], "tags": [ { "name": "gemini-3.1-flash-image", "description": "Gemini-compatible image generation with gemini-3.1-flash-image." } ], "security": [ { "geminiApiKeyAuth": [] } ], "paths": { "/v1beta/models/gemini-3.1-flash-image:generateContent": { "post": { "tags": [ "gemini-3.1-flash-image" ], "operationId": "generateGemini31FlashImageContent", "summary": "Gemini 3.1 Flash Image Generation", "description": "Generate text and image content using the Gemini-compatible\n`generateContent` API. For text-to-image calls, the source document\nnotes that `generationConfig.responseModalities` must include `IMAGE`\nand may include `TEXT`.\n", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/Gemini31FlashImageGenerateContentRequest" }, "examples": { "anatomicalButterfly": { "summary": "Text-to-image request with text and image response modalities", "value": { "contents": [ { "parts": [ { "text": "Da Vinci style anatomical sketch of a dissected Monarch butterfly. Detailed drawings of the head, wings, and legs on textured parchment with notes in English." } ] } ], "tools": [ { "google_search": {} } ], "generationConfig": { "responseModalities": [ "TEXT", "IMAGE" ], "imageConfig": { "aspectRatio": "1:1", "imageSize": "1K" } } } }, "halfKCat": { "summary": "0.5K image-only request", "value": { "contents": [ { "parts": [ { "text": "一只坐着的橙色小猫，正面，纯色背景" } ] } ], "generationConfig": { "responseModalities": [ "IMAGE" ], "imageConfig": { "aspectRatio": "1:1", "imageSize": "512" } } } } } } } }, "responses": { "200": { "description": "Generated content response containing candidate text and/or inline image data.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/Gemini31FlashImageGenerateContentResponse" }, "examples": { "textAndImage": { "summary": "Source document response with text and inline image data", "value": { "candidates": [ { "content": { "parts": [ { "text": "Here is the anatomical sketch of a dissected Monarch butterfly in Da Vinci style..." }, { "inlineData": { "data": "iVBORw0KGgoAAAANSUhEUgAA...", "mimeType": "image/png" } } ], "role": "model" }, "finishReason": "STOP" } ], "usageMetadata": { "candidatesTokenCount": 1315, "totalTokenCount": 1331 } } }, "imageOnly": { "summary": "Image-only response with inline PNG data", "value": { "candidates": [ { "content": { "parts": [ { "inlineData": { "data": "iVBORw0KGgoAAAANSUhEUgAA...", "mimeType": "image/png" } } ], "role": "model" }, "finishReason": "STOP" } ], "usageMetadata": { "candidatesTokenCount": 1315, "totalTokenCount": 1331 } } } } } } }, "400": { "description": "Invalid request parameters or generation error.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/Gemini31FlashImageErrorResponse" }, "examples": { "documentedError": { "$ref": "#/components/examples/Gemini31FlashImageError" } } } } }, "default": { "description": "Error response.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/Gemini31FlashImageErrorResponse" }, "examples": { "documentedError": { "$ref": "#/components/examples/Gemini31FlashImageError" } } } } } } } } }, "components": { "securitySchemes": { "geminiApiKeyAuth": { "type": "apiKey", "in": "header", "name": "x-goog-api-key", "description": "ModelVerse API key sent in the documented `x-goog-api-key:\n` header for the Gemini-compatible endpoint.\n" } }, "schemas": { "Gemini31FlashImageGenerateContentRequest": { "type": "object", "additionalProperties": false, "required": [ "contents" ], "properties": { "contents": { "type": "array", "minItems": 1, "description": "Request contents containing one or more content parts.", "items": { "$ref": "#/components/schemas/Gemini31FlashImageRequestContent" } }, "tools": { "type": "array", "description": "Tool configuration. The source request example includes `google_search`.", "items": { "$ref": "#/components/schemas/Gemini31FlashImageTool" } }, "generationConfig": { "$ref": "#/components/schemas/Gemini31FlashImageGenerationConfig" } } }, "Gemini31FlashImageRequestContent": { "type": "object", "additionalProperties": false, "required": [ "role", "parts" ], "properties": { "role": { "type": "string", "const": "user", "default": "user", "description": "Content role documented for requests; fixed to `user`." }, "parts": { "type": "array", "minItems": 1, "description": "Content parts for the request.", "items": { "$ref": "#/components/schemas/Gemini31FlashImageRequestPart" } } } }, "Gemini31FlashImageRequestPart": { "type": "object", "additionalProperties": false, "properties": { "text": { "type": "string", "minLength": 1, "description": "Text prompt." } } }, "Gemini31FlashImageTool": { "type": "object", "additionalProperties": false, "properties": { "google_search": { "type": "object", "additionalProperties": false, "description": "Empty Google Search tool configuration shown in the source request example." } } }, "Gemini31FlashImageGenerationConfig": { "type": "object", "additionalProperties": false, "properties": { "responseModalities": { "type": "array", "default": [ "TEXT", "IMAGE" ], "description": "Expected response modalities.", "items": { "type": "string", "enum": [ "TEXT", "IMAGE" ] } }, "imageConfig": { "$ref": "#/components/schemas/Gemini31FlashImageConfig" } } }, "Gemini31FlashImageConfig": { "type": "object", "additionalProperties": false, "properties": { "aspectRatio": { "type": "string", "default": "1:1", "description": "Output image aspect ratio.", "enum": [ "1:1", "2:3", "3:2", "3:4", "4:3", "4:5", "5:4", "9:16", "16:9", "21:9" ] }, "imageSize": { "type": "string", "default": "1K", "description": "Output image resolution. The `512` value is documented without a `K` suffix.", "enum": [ "512", "1K", "2K", "4K" ] } } }, "Gemini31FlashImageGenerateContentResponse": { "type": "object", "additionalProperties": false, "required": [ "candidates" ], "properties": { "candidates": { "type": "array", "description": "Candidate content returned by the model.", "items": { "$ref": "#/components/schemas/Gemini31FlashImageCandidate" } }, "usageMetadata": { "$ref": "#/components/schemas/Gemini31FlashImageUsageMetadata" } } }, "Gemini31FlashImageCandidate": { "type": "object", "additionalProperties": false, "properties": { "content": { "$ref": "#/components/schemas/Gemini31FlashImageResponseContent" }, "finishReason": { "type": "string", "description": "Generation finish reason, such as `STOP`.", "examples": [ "STOP" ] } } }, "Gemini31FlashImageResponseContent": { "type": "object", "additionalProperties": false, "properties": { "parts": { "type": "array", "description": "Response parts, which may include text and inline image data.", "items": { "$ref": "#/components/schemas/Gemini31FlashImageResponsePart" } }, "role": { "type": "string", "description": "Candidate content role returned by the model.", "examples": [ "model" ] } } }, "Gemini31FlashImageResponsePart": { "type": "object", "additionalProperties": false, "anyOf": [ { "required": [ "text" ] }, { "required": [ "inlineData" ] } ], "properties": { "text": { "type": "string", "description": "Text returned by the model." }, "inlineData": { "$ref": "#/components/schemas/Gemini31FlashImageInlineData" }, "thought": { "type": "boolean", "description": "Whether this part is an intermediate thought part; clients can skip thought images and keep final output images." } } }, "Gemini31FlashImageInlineData": { "type": "object", "additionalProperties": false, "required": [ "data", "mimeType" ], "properties": { "data": { "type": "string", "description": "Base64-encoded image data." }, "mimeType": { "type": "string", "description": "MIME type for the inline image data.", "examples": [ "image/png" ] } } }, "Gemini31FlashImageUsageMetadata": { "type": "object", "additionalProperties": false, "properties": { "candidatesTokenCount": { "type": "integer", "minimum": 0, "description": "Candidate token count shown in the source response example." }, "totalTokenCount": { "type": "integer", "minimum": 0, "description": "Total token count shown in the source response example." } } }, "Gemini31FlashImageErrorResponse": { "type": "object", "additionalProperties": false, "required": [ "error" ], "properties": { "error": { "$ref": "#/components/schemas/Gemini31FlashImageErrorObject" } } }, "Gemini31FlashImageErrorObject": { "type": "object", "additionalProperties": false, "required": [ "message", "type", "param", "code" ], "properties": { "message": { "type": "string", "description": "Error message." }, "type": { "type": "string", "description": "Error type." }, "param": { "type": "string", "description": "Request identifier, documented as `request_id`." }, "code": { "type": "string", "description": "Error code." } } } }, "examples": { "Gemini31FlashImageError": { "summary": "Documented error response", "value": { "error": { "message": "error_message", "type": "error_type", "param": "request_id", "code": "error_code" } } } } } } ```