Gemini Image Generation Guide

Reference for generating images with Google's gemini-3-pro-image-preview model.

Language References

Load the appropriate reference based on the project's language:

Language	Reference File
Python	references/python.md

Instructions: When implementing Gemini image generation, read the corresponding language reference file for complete code patterns and examples.

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Model Information

Property	Value
Model ID	gemini-3-pro-image-preview
Cost	~$0.134 per image (2K)
Max Reference Images	5+ (high fidelity)
Resolutions	1K, 2K, 4K

Supported Aspect Ratios

Ratio	Use Case
1:1	Square, social media posts
2:3	Portrait photos
3:2	Landscape photos
3:4	Portrait, mobile screens
4:3	Standard display
4:5	Instagram portrait
5:4	Large format
9:16	Vertical video, stories
16:9	Widescreen, presentations
21:9	Ultra-wide, cinematic

Image Sizes

Size	Resolution	Use Case
1K	~1024px	Thumbnails, previews
2K	~2048px	Standard output (recommended)
4K	~4096px	High-quality prints

Important: Use uppercase "K" (not "1k", "2k", "4k").

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Environment Setup

export GOOGLE_API_KEY='your-api-key-here'

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Core Capabilities

1. Text-to-Image Generation

Generate images from text descriptions with configurable aspect ratio and resolution.

2. Style Transfer with Reference Images

Pass reference images to maintain consistent style across generations. Supports up to 5+ images for high fidelity.

3. Image Editing

Modify existing images based on text instructions (add/remove elements, style changes).

4. Batch Generation

Generate multiple style candidates or variations.

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Prompt Engineering Tips

Be Descriptive

Bad:  "cat, sunset"
Good: "A fluffy orange tabby cat sitting on a wooden fence,
       watching a vibrant sunset over rolling hills.
       Warm golden and pink light illuminates the scene.
       Photorealistic style with soft focus background."

Specify Visual Elements

• Lighting: "soft morning light", "dramatic side lighting", "golden hour"
• Style: "oil painting", "watercolor", "3D render", "photorealistic"
• Mood: "serene", "dramatic", "whimsical", "mysterious"
• Composition: "close-up portrait", "wide landscape", "bird's eye view"
• Camera: "35mm lens", "shallow depth of field", "wide angle"

For Style Transfer

When using reference images, be explicit about what to transfer:

• "Match the color palette and brushstroke style of the reference"
• "Keep the artistic mood and lighting from the reference image"

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Common Issues

Issue	Solution
"No image generated"	Check prompt for content policy violations; simplify prompt
"Invalid image_size"	Use uppercase: "1K", "2K", "4K"
"API key not found"	Set GOOGLE_API_KEY environment variable
Rate limits	Add delays between requests; use exponential backoff

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Pricing Comparison

Model	Cost per Image
gemini-3-pro-image-preview	~$0.134
gemini-2.5-flash-image	~$0.039