ComfyUI Extension: ComfyUI-Outpainting-Gemini

Authored by jzhang-POP

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Run ComfyUI workflows without the setup

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Simple Gemini API node & AR/Resolution calculator & Compositing

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Custom Nodes (5)

README

ComfyUI-Outpainting-Gemini

ComfyUI custom nodes for Gemini image generation and Nano Banana Pro outpainting workflows.

Nodes

Gemini Image Generate

Generate or transform images using Gemini 3 API.

Inputs:

  • image: Input image
  • prompt: Text prompt
  • api_key: Gemini API key
  • model: gemini-3-pro-image-preview or gemini-3-nano-image-preview
  • aspect_ratio: Target aspect ratio (STRING, wirable)
  • resolution: Target resolution (STRING, wirable)

Nano Banana Pad Calculator

Calculate optimal padding to reach a supported Nano Banana Pro dimension.

Inputs:

  • image: Input image
  • aspect_ratio: Target aspect ratio or "auto" (finds smallest fit)
  • resolution: "1K", "2K", "4K", or "auto"

Outputs:

  • pad_left, pad_right, pad_top, pad_bottom: Padding values
  • target_w, target_h: Target dimensions
  • aspect_ratio, resolution: Resolved values (for wiring to Gemini node)

Supported Dimensions

| API Param | 1K | 2K | 4K | |-----------|-----|------|------| | 21:9 | 1584x672 | 3168x1344 | 6336x2688 | | 16:9 | 1376x768 | 2752x1536 | 5504x3072 | | 3:2 | 1264x848 | 2528x1696 | 5056x3392 | | 4:3 | 1200x896 | 2400x1792 | 4800x3584 | | 5:4 | 1152x928 | 2304x1856 | 4608x3712 | | 1:1 | 1024x1024 | 2048x2048 | 4096x4096 | | 4:5 | 928x1152 | 1856x2304 | 3712x4608 | | 3:4 | 896x1200 | 1792x2400 | 3584x4800 | | 2:3 | 848x1264 | 1696x2528 | 3392x5056 | | 9:16 | 768x1376 | 1536x2752 | 3072x5504 |

Installation

cd ComfyUI/custom_nodes
git clone https://github.com/YOUR_USERNAME/Vermeer-Gemini.git

Restart ComfyUI.

Outpainting Workflow

Load Image
    │
    ▼
Nano Banana Pad Calculator (auto/auto)
    │
    ├── pad values ──► ImagePadForOutpaint (feather=0)
    │                        │
    │                        ├── padded image ──► Gemini Image Generate
    │                        │                           │
    │                        │                           ▼
    │                        │                    ┌──────────────────┐
    │                        │                    │ImageCompositeMasked│
    │                        │                    │ destination = J    │
    │                        └── mask (inverted) ─│ mask              │
    │                                             │ x = pad_left      │
    │                                             │ y = pad_top       │
    └── aspect_ratio, resolution ──► Gemini      └──────────────────┘
                                                          │
Original Image ──► SolidMask (white) ────────────────────►│ source + mask
                                                          ▼
                                                     Save Image

License

MIT

Run ComfyUI workflows without the setup

No installs, no CUDA version roulette, no GPU sitting idle on your bill. Bring a workflow and run it in the browser.

Learn more