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How to Generate Images with One API (2026 Guide)

A practical AI image generation API tutorial: call gpt-image-2, Gemini, and Seedream through one OpenAI-compatible endpoint, pick sizes and quality, edit existing images, and see the exact cost of every generation.

A glowing image frame being generated on a circuit board, representing an AI image generation API

Every image model ships behind a different API. OpenAI's gpt-image-2 wants one SDK, Gemini image models another, Seedream a third — each with its own auth, parameters, and billing. If you want to compare outputs or switch models later, you rewrite your integration every time.

DigitSpace solves this with one OpenAI-compatible image generation API. POST /v1/images/generations reaches every image model in the catalog — browse them with the image filter — with one API key and one response format.

Generate your first image

Grab an API key from the dashboard, then:

1curl -X POST "https://api.digitspace.ai/v1/images/generations" \2  -H "Authorization: Bearer $DIGITSPACE_API_KEY" \3  -H "Content-Type: application/json" \4  -d '{5    "model": "gemini-3-pro-image-preview",6    "prompt": "A cute cat wearing a tiny top hat",7    "n": 1,8    "size": "1024x1024"9  }'

The response contains base64-encoded images:

1{2  "created": 1753500000,3  "data": [{ "b64_json": "iVBORw0KGgo..." }]4}

Leave model out (or pass "auto") and the gateway picks a strong default image model for you.

Use your existing OpenAI SDK

Because the endpoint is OpenAI-compatible, the standard client works — change the base URL and nothing else:

1import OpenAI from "openai";2import { writeFileSync } from "fs";3
4const client = new OpenAI({5  baseURL: "https://api.digitspace.ai/v1",6  apiKey: process.env.DIGITSPACE_API_KEY,7});8
9const response = await client.images.generate({10  model: "gpt-image-2",11  prompt: "A futuristic city skyline at sunset with flying cars",12  n: 1,13  size: "1536x1024",14});15
16response.data.forEach((image, i) => {17  if (image.b64_json) {18    writeFileSync(`image-${i}.png`, Buffer.from(image.b64_json, "base64"));19  }20});

Switching from gpt-image-2 to a Gemini or Seedream model is a one-line change to model — same request, same response shape.

DigitSpace

One API key for every model.

Route to 200+ models with automatic failover, caching, and real-time cost analytics. Free to start — no credit card required.

Create free accountBrowse all models

The parameters that matter

Parameter What it does
prompt Required. Text description of the image
model Any image model; defaults to auto
n 1–10 images per request
size Pixel dimensions like 1024x1024 or 1536x1024, model-dependent
quality low, medium, high, or auto on models that support it
aspect_ratio 1:1, 16:9, 4:3, … — takes precedence over size where supported
style vivid or natural

Two model-specific notes worth knowing: aspect_ratio works on Gemini image models while OpenAI's gpt-image-2 ignores it (use an exact size instead), and quality applies to gpt-image-2. The image generation docs list per-model behavior.

Edit existing images

POST /v1/images/edits takes one or more input images (HTTPS URLs or base64 data URLs) plus an edit prompt:

1curl -X POST "https://api.digitspace.ai/v1/images/edits" \2  -H "Authorization: Bearer $DIGITSPACE_API_KEY" \3  -H "Content-Type: application/json" \4  -d '{5    "images": [{ "image_url": "https://example.com/product.png" }],6    "prompt": "Place the product on a marble table with soft window light",7    "quality": "high"8  }'

You can control background (transparent, opaque, auto), output_format (png, jpeg, webp), and output_compression for the encoded result.

Using the Vercel AI SDK

If you build with the AI SDK, the @llmgateway/ai-sdk-provider package supports generateImage directly:

1import { createLLMGateway } from "@llmgateway/ai-sdk-provider";2import { generateImage } from "ai";3
4const llmgateway = createLLMGateway({5  apiKey: process.env.DIGITSPACE_API_KEY,6});7
8const result = await generateImage({9  model: llmgateway.image("gemini-3-pro-image-preview"),10  prompt: "A cozy cabin in a snowy mountain landscape at night",11  size: "1024x1024",12});

See the AI SDK developer docs for chat-based image streaming with useChat.

Know what every image costs

Every generation is logged with its exact cost. The Activity page shows per-request image output costs, and the dashboard rolls them up by model and project — so you can compare not just output quality across models, but price per image. Set a spending limit on the API key if you want a hard cap.

Get started:

DigitSpace

One API key for every model.

Route to 200+ models with automatic failover, caching, and real-time cost analytics. Free to start — no credit card required.

Create free accountBrowse all models

Frequently asked questions

Which image generation models can I use through the API?
Every model on the models page with the image filter — including OpenAI, Google, ByteDance, Alibaba, xAI, and more — through the same endpoint. The list updates as new models ship.
Do I need separate API keys per provider?
No. One DigitSpace key covers every provider. You can bring your own provider keys for free, or use pay-as-you-go credits with a flat 5% platform fee.
Can I generate images conversationally?
Yes. Multimodal models like gemini-3-pro-image-preview can return images through /v1/chat/completions, which is useful for iterative editing in a chat UI. The image generation docs cover the chat flow.
Is there a way to try models before writing code?
The Image Studio in DigitSpace Chat generates 1, 2, or 4 images per prompt and lets you compare models side by side.