Nanobanana Image Gen

Nanobanana Image Generation

Overview

This skill enables image generation and editing using Google's Nanobanana model (google/nano-banana) through the Replicate API. Generate images from text prompts, transform existing images, apply style transfers, or create variations with precise control over aspect ratios and output formats.

Core Capabilities

1. Text-to-Image Generation

Generate images from natural language descriptions.

Example requests:

• "Generate an image of a sunset over snow-capped mountains"
• "Create a portrait of a cat wearing a bow tie in a Victorian setting"
• "Make me an abstract image with blue and purple swirls"

Process:

1. Extract the text description from the user's request
2. Determine appropriate aspect ratio (default: 1:1 for general images, 16:9 for landscapes, 2:3 for portraits)
3. Execute scripts/generate_image.py with the prompt
4. Save the generated image to the user's working directory

2. Image-to-Image Transformation

Transform or edit existing images using text prompts.

Example requests:

• "Make this photo look like a watercolor painting"
• "Transform this image to black and white with high contrast"
• "Turn this photo into an anime-style illustration"
• "Edit this image to make it look like it was taken at golden hour"

Process:

1. Ensure the input image is accessible (local file or URL)
2. If local file, it must be uploaded to a publicly accessible URL first (use appropriate upload method)
3. Extract the transformation instructions from the user's request
4. Execute scripts/generate_image.py with both prompt and image input
5. Save the transformed image to the user's working directory

3. Multi-Image Input

Use multiple images as references or inputs for generation.

Example requests:

• "Combine the style of this painting with the subject of this photo"
• "Generate an image that merges elements from these three images"
• "Create a variation that incorporates aspects from both of these images"

Process:

1. Ensure all input images are accessible as URLs
2. Provide all image URLs in the image_input array parameter
3. Execute scripts/generate_image.py with the prompt and multiple image inputs

4. Aspect Ratio Control

Generate images with specific dimensions for different use cases.

Available aspect ratios:

• 1:1 - Square (social media posts, profile pictures)
• 16:9 - Widescreen (presentations, YouTube thumbnails)
• 9:16 - Vertical (mobile stories, TikTok)
• 4:3 - Standard (traditional photos)
• 3:4 - Portrait orientation
• 21:9 - Ultra-wide (cinematic)
• 4:5 - Instagram portrait
• 5:4 - Medium format
• 2:3 - Portrait photos
• 3:2 - Landscape photos
• match_input_image - Match input image dimensions (default when image input provided)

Example requests:

• "Generate a 16:9 banner image of a forest"
• "Create a square profile picture of a logo"
• "Make a vertical 9:16 image for Instagram stories"

Using the Generation Script

The scripts/generate_image.py script handles all Replicate API interactions with proper error handling and polling.

Basic usage:

python scripts/generate_image.py "a sunset over mountains" --output sunset.jpg

With image input:

python scripts/generate_image.py "make this look like a watercolor" \
  --image-input https://example.com/photo.jpg \
  --output watercolor.jpg

With multiple images:

python scripts/generate_image.py "combine these styles" \
  --image-input https://example.com/img1.jpg \
  --image-input https://example.com/img2.jpg \
  --output combined.jpg

Custom aspect ratio:

python scripts/generate_image.py "a wide landscape" \
  --aspect-ratio 21:9 \
  --output landscape.jpg

PNG output:

python scripts/generate_image.py "transparent logo concept" \
  --output-format png \
  --output logo.png

Important Implementation Details

Image URL Requirements

Replicate requires images to be uploaded to their file hosting service. The script automatically handles this:

1. If the input is a URL from any domain, the script downloads and re-uploads to Replicate
2. If the input is a local file path, the script reads and uploads to Replicate
3. This ensures compatibility with the Nanobanana model's requirements

Error Handling

The script includes comprehensive error handling:

• API authentication failures (missing or invalid REPLICATE_API_KEY)
• Network timeouts and connection errors
• Invalid image URLs or file paths
• Model execution failures with helpful error messages

Output Files

Generated images are saved to the specified output path. If no output path is specified, the script saves to ./generated_image_{timestamp}.jpg in the current directory.

Performance Considerations

• Image generation typically takes 5-15 seconds depending on complexity
• The script uses polling with appropriate intervals (configurable)
• Progress indicators show generation status
• Timeout is set to 5 minutes by default to handle complex generations

API Reference

For detailed information about the Nanobanana model parameters, capabilities, and best practices, refer to references/nanobanana-api.md.

Environment Setup

Ensure the REPLICATE_API_KEY environment variable is set:

export REPLICATE_API_KEY="your-api-key-here"

Get an API key from https://replicate.com/account/api-tokens

Common Pitfalls

1. Image URLs not publicly accessible: Ensure input images are either publicly accessible URLs or properly uploaded to Replicate's file hosting
2. Missing API key: The script will fail if REPLICATE_API_KEY is not set in the environment
3. Aspect ratio mismatch: When using match_input_image, ensure at least one input image is provided
4. File path issues: Always use absolute paths or properly resolve relative paths for local image files

Best Practices

1. Descriptive prompts: More detailed prompts generally produce better results (e.g., "a serene mountain lake at sunset with pine trees in the foreground" vs "a lake")
2. Appropriate aspect ratios: Choose aspect ratios that match the intended use case
3. Image quality: When using image inputs, higher quality source images generally produce better results
4. Iterative refinement: Generate multiple variations by adjusting prompts to find the best result
5. Output format: Use PNG for images requiring transparency, JPG for photographs and general images (smaller file size)

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