nano-banana-2

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Generate and edit images using Google's Nano Banana 2 (Gemini 3.1 Flash Image Preview) API. This skill should be used when the user asks to create or modify images, especially when they need fast iteration, explicit aspect-ratio control, or resolution control from 512px to 4K.

2installs
Sourceintellectronica/agent-skills
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NPX Install

npx skill4agent add intellectronica/agent-skills nano-banana-2

Tags

Translated version includes tags in frontmatter
image-generationimage-editinggemini-apinano-banana-2resolution-control

SKILL.md Content

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Nano Banana 2 Image Generation & Editing

Generate new images or edit existing images with Nano Banana 2 (
gemini-3.1-flash-image-preview
).

Usage

Run the script using absolute or workspace-relative path (do NOT cd into the skill directory first):
Generate new image:
bash
uv run ./.agents/skills/nano-banana-2/scripts/generate_image.py --prompt "your image description" --filename "output-name.png" [--resolution 512px|1K|2K|4K] [--aspect-ratio RATIO] [--api-key KEY]
Edit image(s) with references:
bash
uv run ./.agents/skills/nano-banana-2/scripts/generate_image.py --prompt "editing instructions" --filename "output-name.png" --input-image "path/to/input1.png" [--input-image "path/to/input2.png" ...] [--resolution 512px|1K|2K|4K] [--aspect-ratio RATIO] [--api-key KEY]
Always run from the user's current working directory so outputs are saved in the active project context.

Model

Use model code:
  • gemini-3.1-flash-image-preview
    (Nano Banana 2)
Do not use 
gemini-3-pro-image-preview
in this skill.

Resolution Options

Nano Banana 2 supports:
  • 512px
    (fastest, low-latency iteration)
  • 1K
    (default)
  • 2K
  • 4K
Map common user language:
  • "quick draft", "thumbnail", "tiny", "512", "0.5K" → 
    512px
  • no resolution mention → 
    1K
  • "2K", "medium", "normal" → 
    2K
  • "4K", "high-res", "ultra", "print quality" → 
    4K
Use uppercase 
K
for 
1K
, 
2K
, 
4K
.

Aspect Ratios

Supported aspect ratios:
  • 1:1
    , 
    1:4
    , 
    1:8
    , 
    2:3
    , 
    3:2
    , 
    3:4
    , 
    4:1
    , 
    4:3
    , 
    4:5
    , 
    5:4
    , 
    8:1
    , 
    9:16
    , 
    16:9
    , 
    21:9
Map common requests:
  • square post / icon → 
    1:1
  • phone wallpaper / vertical reel → 
    9:16
  • widescreen / slide / hero image → 
    16:9
  • cinematic wide → 
    21:9
  • portrait print → 
    2:3
    or 
    3:4
  • panorama banner → 
    4:1
    or 
    8:1
If unspecified, let the model default behavior apply.

Reference Images (New in Gemini 3 Image workflows)

Provide up to 14 reference images when needed by repeating 
--input-image
:
  • preserve character consistency
  • preserve object fidelity
  • combine multiple visual references into one output
Use one image for simple edits; use multiple images for composition or consistency-sensitive tasks.

API Key

Resolve API key in this order:
  1. --api-key
    argument
  2. GEMINI_API_KEY
    environment variable
If no key is available, stop and report a clear error.

Filename Generation

Generate filenames as: 
yyyy-mm-dd-hh-mm-ss-name.png
Examples:
  • 2026-02-26-17-31-04-japanese-garden.png
  • 2026-02-26-17-31-59-social-banner.png

Prompt Handling

For generation, pass the user's request as-is unless critically underspecified. For editing, include explicit transformation instructions in the prompt and preserve the original intent.

Output

  • Save PNG to the current directory (or to a provided path in 
    --filename
    )
  • Return the full saved path(s)
  • Do not read the output image back unless explicitly requested

Examples

Create a 4K widescreen image:
bash
uv run ./.agents/skills/nano-banana-2/scripts/generate_image.py --prompt "Futuristic city skyline at blue hour with neon reflections" --filename "2026-02-26-17-45-00-futuristic-skyline.png" --resolution 4K --aspect-ratio 16:9
Edit with multiple references:
bash
uv run ./.agents/skills/nano-banana-2/scripts/generate_image.py --prompt "Create a polished campaign image that keeps the exact logo details and character identity" --filename "2026-02-26-17-50-10-campaign-image.png" --input-image "logo.png" --input-image "character.png" --resolution 2K --aspect-ratio 4:5