Gemini imagegen

Skill weorbitant/compound-engineering-feat-python-plugin/skills/gemini-imagegen

This skill should be used when generating and editing images using the Gemini API (Nano Banana Pro). It applies when creating images from text prompts, editing existing images, applying style transfers, generating logos with text, creating stickers, product mockups, or any image generation/manipulation task. Supports text-to-image, image editing, multi-turn refinement, and composition from multiple reference images.From its SKILL.md

Install

npx -y skills add weorbitant/compound-engineering-feat-python-plugin --skill gemini-imagegen

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SKILL.md

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Gemini Image Generation (Nano Banana Pro)

Generate and edit images via Google's Gemini API. Requires GEMINI_API_KEY env var.

Model

Always use gemini-3-pro-image-preview (Pro, 1K-4K). Only switch models if explicitly requested.

Defaults

Resolution: 1K — options 1K, 2K, 4K
Aspect ratio: 1:1 — options 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9

CRITICAL: File format

The API returns JPEG by default. Always save with .jpg:

image.save("output.jpg")   # ✅ correct
image.save("output.png")   # ❌ JPEG with PNG extension → media-type errors

Convert to PNG only if needed — see references/examples.md.

Code examples

All patterns (basic generation, custom resolution, editing, multi-turn, Search grounding, multi-reference composition, prompting recipes) in references/examples.md.

Minimal example:

import os
from google import genai
from google.genai import types

client = genai.Client(api_key=os.environ["GEMINI_API_KEY"])
response = client.models.generate_content(
    model="gemini-3-pro-image-preview",
    contents=["Your prompt"],
    config=types.GenerateContentConfig(response_modalities=['TEXT', 'IMAGE']),
)
for part in response.parts:
    if part.inline_data:
        part.as_image().save("output.jpg")

Prompting tips

Photorealistic: include camera details (lens, lighting, angle, mood).
Stylized art: specify style explicitly (kawaii, cel-shading, watercolor).
Text in images: specify font style, placement.
Product mockups: describe lighting setup and surface.
Editing: describe changes conversationally — model handles semantic masking.

Notes

All generated images include SynthID watermarks.
Image-only mode (responseModalities: ["IMAGE"]) does not work with Google Search grounding.
Default to 1K for speed; bump to 2K/4K when quality is critical.

Scripts

Helper CLI utilities (install dependencies with pip install -r requirements.txt):

generate_image.py — text-to-image generation
edit_image.py — edit an existing image with a text instruction
compose_images.py — combine multiple reference images
multi_turn_chat.py — interactive multi-turn refinement
gemini_images.py — importable library wrapping the above