image-generation-gpt-image

GPT Image 1.5 - Image Generation & Editing

Generate new images or edit existing ones using OpenAI's GPT Image 1.5 model.

• Generation: Uses the Images API (images.generate) with gpt-image-1.5
• Editing: Uses the Image API for reliable mask-based inpainting

Usage

Run the script using absolute path (do NOT cd to skill directory first):

Generate new image:

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "your image description" --filename "output-name.png" [--quality low|medium|high] [--size 1024x1024|1024x1536|1536x1024|auto] [--background transparent|opaque|auto] [--api-key KEY] [--azure-endpoint ENDPOINT]

Edit existing image (without mask - full image edit):

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "editing instructions" --filename "output-name.png" --input-image "path/to/input.png" [--size 1024x1024|1024x1536|1536x1024|auto] [--api-key KEY] [--azure-endpoint ENDPOINT]

Edit existing image (with mask - precise inpainting):

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "what to put in masked area" --filename "output-name.png" --input-image "path/to/input.png" --mask "path/to/mask.png" [--size 1024x1024|1024x1536|1536x1024|auto] [--api-key KEY] [--azure-endpoint ENDPOINT]

Important: Always run from the user's current working directory so images are saved where the user is working, not in the skill directory.

Parameters

Quality Options

• low - Fastest generation, lower quality
• medium (default) - Balanced quality and speed
• high - Best quality, slower generation

Map user requests:

• No mention of quality -> medium
• "quick", "fast", "draft" -> low
• "high quality", "best", "detailed", "high-res" -> high

Size Options

• 1024x1024 (default) - Square format
• 1024x1536 - Portrait format
• 1536x1024 - Landscape format
• auto - Let the model decide based on prompt

Map user requests:

• No mention of size -> 1024x1024
• "square" -> 1024x1024
• "portrait", "vertical", "tall" -> 1024x1536
• "landscape", "horizontal", "wide" -> 1536x1024

Background Options (generation only)

• auto (default) - Model decides
• transparent - Transparent background (PNG/WebP output)
• opaque - Solid background

Authentication

The script supports two authentication methods. Azure credentials are used by default when no API key is provided.

Default: Azure AI Foundry (DefaultAzureCredential)

When no --api-key or OPENAI_API_KEY is set, the script authenticates via DefaultAzureCredential (az login, VS Code login, managed identity, etc.) using the OpenAI client with an Azure base_url.

• --azure-endpoint - Azure OpenAI endpoint URL (default: https://ai-foundry-ai-agents-for-beginners.openai.azure.com/)

No API key is needed - the script obtains a bearer token from the logged-in Azure session.

Override: API Key (OpenAI direct)

1. --api-key argument (use if user provided key in chat)
2. OPENAI_API_KEY environment variable

Filename Generation

Generate filenames with the pattern: yyyy-mm-dd-hh-mm-ss-name.png

Format: {timestamp}-{descriptive-name}.png

• Timestamp: Current date/time in format yyyy-mm-dd-hh-mm-ss (24-hour format)
• Name: Descriptive lowercase text with hyphens
• Keep the descriptive part concise (1-5 words typically)
• Use context from user's prompt or conversation
• If unclear, use random identifier (e.g., x9k2, a7b3)

Examples:

• Prompt "A serene Japanese garden" -> 2025-12-17-14-23-05-japanese-garden.png
• Prompt "sunset over mountains" -> 2025-12-17-15-30-12-sunset-mountains.png
• Prompt "create an image of a robot" -> 2025-12-17-16-45-33-robot.png
• Unclear context -> 2025-12-17-17-12-48-x9k2.png

Image Editing

Both editing modes use the Image API (images.edit endpoint) with gpt-image-1.5 for reliable results.

Without Mask (Full Image Edit)

When the user wants to modify an existing image without specifying exact regions:

1. Use --input-image parameter with the path to the image
2. The prompt should contain editing instructions (e.g., "make the sky more dramatic", "change to cartoon style")
3. A fully transparent mask is auto-generated, allowing the model to edit the entire image

With Mask (Precise Inpainting)

When the user wants to edit specific regions:

1. Use --input-image parameter with the path to the image
2. Use --mask parameter with a PNG mask file
3. The mask should have transparent areas (alpha=0) where edits should occur
4. The prompt describes what should appear in the masked region

Common editing tasks: add/remove elements, change style, adjust colors, replace backgrounds, etc.

Prompt Handling

For generation: Pass user's image description as-is to --prompt. Only rework if clearly insufficient.

For editing: Pass editing instructions in --prompt (e.g., "add a rainbow in the sky", "make it look like a watercolor painting")

Preserve user's creative intent in both cases.

Output

• Saves PNG to current directory (or specified path if filename includes directory)
• Script outputs the full path to the generated image
• Do not read the image back - just inform the user of the saved path

Examples

Generate new image:

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "A serene Japanese garden with cherry blossoms" --filename "2025-12-17-14-23-05-japanese-garden.png" --quality high --size 1536x1024

Generate with transparent background:

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "A cute cartoon cat mascot" --filename "2025-12-17-14-25-30-cat-mascot.png" --background transparent --quality high

Edit existing image (full image):

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "make the sky more dramatic with storm clouds" --filename "2025-12-17-14-27-00-dramatic-sky.png" --input-image "original-photo.jpg"

Edit with mask (inpainting):

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "a flamingo swimming" --filename "2025-12-17-14-30-00-lounge-flamingo.png" --input-image "lounge.png" --mask "mask.png"

Generate using Azure AI Foundry (no API key needed):

uv run ~/.github/skills/image-generation-gpt-image/scripts/generate_image.py --prompt "A futuristic cityscape" --filename "2025-12-17-14-35-00-cityscape.png" --azure-endpoint "https://my-resource.openai.azure.com/" --quality high