Google Gemini

Invoke supports Google’s Gemini image generation models through the Gemini API. This provider is a good fit if you want high-quality text-to-image and reference-based image edits without running a local model.

Getting an API Key

1. Open Google AI Studio and sign in with your Google account.
2. Generate a new API key.
3. Note the key — it will only be shown once.

Configuration

Add your key to api_keys.yaml in your Invoke root directory:

external_gemini_api_key: "your-gemini-api-key"

# Optional — only set this if you need to route requests through a different endpoint
external_gemini_base_url: "https://generativelanguage.googleapis.com"

Restart Invoke for the change to take effect.

Available Models

Model	Modes	Reference Images	Notes
Gemini 2.5 Flash Image	txt2img	Yes	10 aspect ratios, fixed per-ratio resolutions.
Gemini 3 Pro Image Preview	txt2img	Up to 14 (6 object + 5 character)	1K / 2K / 4K resolution presets.
Gemini 3.1 Flash Image Preview	txt2img	Up to 14 (10 object + 4 character)	512 / 1K / 2K / 4K resolution presets.

Reference-image input is used to condition generation but counts as txt2img — neither img2img (denoising strength) nor inpaint (mask) is supported for Gemini.

All Gemini models are single-image-per-request — batch size is fixed at 1. To generate multiple variations, queue multiple invocations.

Provider-Specific Options

Selecting a Gemini model adds a Provider options section to the Generate panel:

• Temperature — Override the sampling temperature (0–2; the provider default is 1).
• Thinking level — minimal or high, or the provider default.

Gemini 3 models list their resolution presets under Provider size in the Size section. Picking one sets the width and height to the preset and sends its named size (1K, 2K, 4K) to the API. The named size and the sampling options are recorded in the image metadata and restored by Recall All and Remix.

Canvas

Gemini models generate only from text, so on the Canvas the bounding box must be free of raster content: hide raster layers or move their content out of the box to generate. Invoke asks for the size whose aspect ratio is closest to the bounding box’s; for Gemini 3 that is the smallest named size covering the box at that ratio, such as 2K for a 2000×2000 box. The result is scaled to cover the bounding box and cropped to it from the center, so it is never stretched.

Tips

1. Reference images are sent directly to the API as inlined PNG data. Large references increase request latency and cost — crop tightly where possible.
2. Aspect ratios are mapped to the closest Gemini-supported ratio. For Gemini 3 models, use the resolution presets to stay at the provider’s native output sizes and avoid unnecessary rescaling.
3. Pricing varies by model and region. Check Google’s documentation before running large batches.