ZenMux Image Gen (Nano Banana 2)

Generate images from text prompts using ZenMux API (Vertex AI protocol with Gemini models). Use when: (1) User wants to generate/create images from text descriptions, (2) User asks for AI image generation, (3) User mentions ZenMux or Gemini image models, (4) User wants to create artwork, illustrations, or visual content programmatically, (5) Image-to-image editing. Supports aspect ratio and resolution control. Requires ZENMUX_API_KEY.

ZenMux Image Generation

Generate images from text prompts using ZenMux API with Google Gemini models.

Quick Start

bash

# Generate image (requires ZENMUX_API_KEY env var)
python3 scripts/generate_image.py "A cute cat" output.png

# With aspect ratio and resolution
python3 scripts/generate_image.py "A cute cat" output.png --aspect-ratio 16:9 --image-size 2K

API Key Setup

Get your API key from https://zenmux.ai.

bash

# Set environment variable
export ZENMUX_API_KEY="sk-..."

Security Rules:

• NEVER use --api-key flag (visible in shell history)
• NEVER commit API keys to git

Script Options

Option	Description
--model MODEL	Model name (default: google/gemini-3.1-flash-image-preview)
--input-image PATH	Input image for image-to-image generation
--temperature N	Randomness 0.0-2.0 (default: 1.0)
--max-tokens N	Max output tokens
--aspect-ratio RATIO	1:1, 2:3, 3:2, 3:4, 4:3, 9:16, 16:9, 21:9
--image-size SIZE	1K (default), 2K, 4K

Image-to-Image

Edit existing images with text prompts:

bash

python3 scripts/generate_image.py "Make it nighttime" result.png --input-image photo.jpg

Available Models

Model	Alias	Use Case
google/gemini-3.1-flash-image-preview	Nano Banana 2	Fast & quality (default)
google/gemini-3-pro-image-preview	Nano Banana Pro	Best quality
google/gemini-2.5-flash-image	Nano Banana	Faster generation

Prompt Tips

Writing effective prompts:

• Be specific: "A golden retriever puppy playing on grass" instead of "a dog"
• Include details: lighting (golden hour, soft light), style (photorealistic, anime, oil painting)
• For image-to-image: describe the desired change clearly, e.g., "Change to nighttime with city lights"
• Try 10+ words for better results

Troubleshooting

Error	Fix
Input image not found	Check file path; verify file exists
Image too large	Max input size is 20 MB; compress before uploading
401 Unauthorized	Check ZENMUX_API_KEY is set correctly
429 Rate limited	Wait and retry, or upgrade to paid tier
Request timeout	API may be slow; wait and retry
Network error	Check internet connection
No image in response	Try a different prompt or model
Poor image quality	Use more descriptive prompt (10+ words)

Script Features

• Timeout protection: Requests timeout after 300 seconds (5 minutes)
• Auto-create directories: Output directories are created automatically
• Auto-rename on conflict: If output file exists, automatically appends number (e.g., image_1.png, image_2.png)
• Input validation: Checks image format, size, and existence
• Clear error messages: Human-readable error explanations
• Format support: JPG, PNG, WebP, GIF input formats

Batch Generation

Generate multiple images by running the script multiple times with different outputs:

bash

# Generate variations of the same prompt
for i in 1 2 3; do
  python3 scripts/generate_image.py "A cute cat in different poses" "cat_$i.png"
done