image-gen

name	image-gen
description	Create and edit images using OpenAI image generation API with GPT image models (gpt-image-1, gpt-image-1-mini, gpt-image-1.5 and later). Use when the user asks to generate an image from a text prompt, edit or modify an existing image, create illustrations, logos, icons, concept art, or any visual content using AI image generation. Also use when combining multiple source images into a new composition.
license	Complete terms in LICENSE.txt
metadata	{"author":"Yohan Lasorsa"}

Image Generation & Editing

Generate and edit images via OpenAI-compatible REST APIs using the bundled Python CLI script. No external dependencies required (Python 3.8+ standard library only). Compatible with OpenAI, Azure OpenAI (v1 endpoint), and other OpenAI-compatible providers.

Quick Reference

Supported Models

Model	Generation	Editing	Notes
gpt-image-1	✓	✓	Base GPT image model
gpt-image-1-mini	✓	✓	Smaller, faster variant
gpt-image-1.5	✓	✓	Latest, most capable

Key Parameters

Parameter	Values	Default	Notes
size	auto, 1024x1024, 1536x1024 (landscape), 1024x1536 (portrait)	auto
quality	auto, low, medium, high	auto
background	auto, transparent, opaque	auto	Transparent requires png or webp output
output_format	png, jpeg, webp	png
output_compression	0–100	100	Only for jpeg/webp
n	1–10	1	Number of images
moderation	auto, low	auto	Generation only

Usage

The script at scripts/image_gen.py is a zero-dependency Python CLI.

Authentication

Variables can be defined in a .env file in the working directory or any parent directory.

Variable	Description	Default
OPENAI_API_KEY	API key (required)	—
OPENAI_BASE_URL	Base URL for custom endpoints (Azure OpenAI, etc.)	https://api.openai.com/v1
OPENAI_IMAGE_MODEL	Default model	gpt-image-1.5

All variables can also be passed as CLI flags (--api-key, --base-url, --model).

Generate an Image

python scripts/image_gen.py generate "A cat wearing a top hat" -o ./output

With full options:

python scripts/image_gen.py generate "A minimalist coffee shop logo" \
  --size 1024x1024 \
  --quality high \
  --background transparent \
  --output-format png \
  -o ./output

Edit an Image

python scripts/image_gen.py edit "Add sunglasses to the person" \
  -i photo.png -o ./output

Multiple input images (up to 16):

python scripts/image_gen.py edit "Create a gift basket with these items" \
  -i item1.png -i item2.png -i item3.png -o ./output

With mask for inpainting:

python scripts/image_gen.py edit "Replace the background with a beach" \
  -i photo.png --mask mask.png -o ./output

Important: Do not pass --model unless the user explicitly asks for a specific model. The default model is resolved from OPENAI_IMAGE_MODEL env var or falls back to gpt-image-1.5.

Prompt Guidelines

For best results with GPT image models:

• Be specific and descriptive: include subject, style, mood, colors, composition.
• Specify the art style: "photorealistic", "watercolor", "flat illustration", "3D render", etc.
• For logos/icons: request "transparent background" and set --background transparent --output-format png.
• For edits: clearly describe what should change and what should remain.
• The maximum prompt length for GPT image models is 32,000 characters.

Output

-o accepts a file path or a directory:

• File path (e.g. -o logo.png): saves directly to that path. With --n >1, appends _1, _2, etc. before the extension. Intermediate directories are created automatically.
• Directory (e.g. -o ./out): saves as image_1.{ext}, image_2.{ext}, etc.

Existing files are never overwritten — a numeric suffix is appended automatically if the target already exists.

The script prints saved file path(s) to stdout (one per line) and any revised prompts to stderr.

Recipes

Before generating an images, always first generate a prompt using these copy/paste instructions for prompt recipes: references/sample-prompts.md.

An image genaration/editing workflow consists of 2 steps:

1. Generate a prompt for the image generation/editing based on the user query using the sample prompts.
2. Pass the generated prompt to the image generation/editing command to generate/edit the image.