Nano Banana Use

Use this skill to generate, edit, and compose images using Gemini's Nano Banana models (gemini-2.5-flash-image and gemini-3-pro-image-preview).

This skill uses portable Python scripts managed by uv.

Prerequisites

Ensure you have one of the following authentication methods configured in your environment:

1. API Key:

   • GOOGLE_API_KEY or GEMINI_API_KEY

2. Vertex AI:

   • GOOGLE_CLOUD_PROJECT
   • GOOGLE_CLOUD_LOCATION
   • GOOGLE_GENAI_USE_VERTEXAI=1

Usage

Generate an Image

Step 1: Confirm Parameters Before running the script, confirm the following parameters with the user or state the defaults you will use:

• Prompt: The image description.
• Model: Default is gemini-3-pro-image-preview.
• Aspect Ratio: Default is 1:1.
• Safety Filter: Default is BLOCK_MEDIUM_AND_ABOVE.

Step 2: Run the Script Run the python script using uv:

uv run skills/nano-banana-use/scripts/generate_image.py "A futuristic banana city" --output city.png

Edit an Image

Modify an existing image based on a text prompt.

uv run skills/nano-banana-use/scripts/edit_image.py original.png "Make the sky purple" --output edited.png

Compose Images

Generate a new image based on multiple input images and a prompt.

uv run skills/nano-banana-use/scripts/compose_image.py --image style.png --image subject.jpg "A painting of the subject in the style of the first image" --output composition.png

Options

• prompt: The text description of the image.
• --model: The model to use. Defaults to gemini-3-pro-image-preview.
• --output: The filename for the saved image. Defaults to generated_image.png.
• --aspect-ratio: The aspect ratio of the generated image. Defaults to 1:1. Supported: 1:1, 16:9, 4:3, 3:4, 9:16.
• --safety-filter-level: Safety filter threshold. Defaults to BLOCK_MEDIUM_AND_ABOVE.