Image Generation

Generate images with Google Gemini image models through GregAPI, supporting OpenAI-compatible, async task, and native generateContent calling styles. All requests are forwarded by GregAPI — no self-signing required, just pass the GregAPI API Key in the header.

export BASE_URL="https://api.gregapi.com/v1"
export TOKEN="oh-xxxxxxxxxxxxxxxx"

Standard headers:

Authorization: Bearer <TOKEN>
Content-Type: application/json

Supported Models

Model	Max resolution	Status	Notes
`gemini-2.5-flash-image`	1K	GA	Fast, low latency, ideal for prototyping; up to 3 reference images per request
`gemini-3-pro-image-preview`	4K	Public Preview	High quality, complex prompt understanding, reference-image editing, thinking / grounding; up to 14 reference images per request
`gemini-3.1-flash-image`	4K	GA	Balanced speed / cost / quality, supports 512/1K/2K/4K and additional aspect ratios; up to 14 reference images per request

Resolution Tiers

The size or imageConfig.imageSize field accepts the following tiers:

Tier	Description
`512`	Low resolution, `gemini-3.1-flash-image` only
`1K`	~1K-class pixels, preview / mobile / small images
`2K`	~2K-class pixels, HD illustration / desktop wallpaper
`4K`	~4K-class pixels, ultra-HD / refined / large display

Supported tiers per model:

gemini-2.5-flash-image: 1K only; higher tiers auto-downgrade to 1K
gemini-3-pro-image-preview: 1K / 2K / 4K
gemini-3.1-flash-image: 512 / 1K / 2K / 4K

Aspect Ratios

All three models support:

1:1  2:3  3:2  3:4  4:3  4:5  5:4  9:16  16:9  21:9

gemini-3.1-flash-image additionally supports:

1:4  4:1  1:8  8:1  9:21

Calling Style Comparison

Feature	OpenAI-compatible	Async	Native API
Endpoints	`/v1/images/generations`, `/v1/images/edits`	`/v1/images/*/async`	`/v1beta/models/{model}:generateContent`
Text-to-image	✅	✅	✅
Reference-image editing	✅	✅	✅
Output	`b64_json` or `url`	Fixed `url` (24h signed URL)	base64
Multiple reference images	Up to 14	Same as sync	Up to 15
Auto resolution inference	Supported (`gemini-3-pro-image-preview` only)	Applies	Not supported
Learning curve	Low (OpenAI SDK compatible)	Medium (polling)	Medium

Billing

Text input: billed by prompt tokens.
Image output: prioritizes upstream usageMetadata image tokens; if unavailable, estimated per tier:
- gemini-2.5-flash-image / gemini-3-pro-image-preview: 1120 tokens per 1K/2K image, 2000 tokens per 4K image.
- gemini-3.1-flash-image: 747 tokens (512), 1120 tokens (1K), 1680 tokens (2K), 2520 tokens (4K).
no-image responses that were already billed return usage: top-level usage for OpenAI-style, usageMetadata for native API, and top-level usage for async task queries.

See the platform’s “Model Pricing” page for exact rates, subject to upstream usage logs.

Large Language Models (LLM)

Image Models

Video Models

Speech Models

Image Generation

Supported Models

Resolution Tiers

Aspect Ratios

Calling Style Comparison

Billing

​Supported Models

​Resolution Tiers

​Aspect Ratios

​Calling Style Comparison

​Billing

Supported Models

Resolution Tiers

Aspect Ratios

Calling Style Comparison

Billing