README

Generates alt texts for images via OpenAI Vision API. Integrates seamlessly into the SilverStripe 6 CMS AssetAdmin — a native FormAction button triggers AI-based generation and saves the result directly.

Requires purplespider/asset-alt-text for the AltText field on Image assets.

Requirements

SilverStripe Framework ^6
purplespider/asset-alt-text ^3
openai-php/client ^0.18.0
PHP 8.1+

Installation

composer require moritz-sauer-13/silverstripe-ai-alt-text

Then run:

vendor/bin/sake dev/build flush=1

Configuration

API Key (required)

Set the OpenAI API key via environment variable (recommended) or YAML config.

Option 1: Environment variable (.env file or server config)

OPENAI_API_KEY="sk-your-api-key-here"

Option 2: YAML config (app/_config/ai-alt-text.yml)

AiAltText\Service\OpenAiVisionClient:
  api_key: 'sk-your-api-key-here'

Note: Environment variables take precedence over YAML config.

Optional Configuration

# Model selection (default: gpt-4o-mini)
AiAltText\Service\OpenAiVisionClient:
  model: 'gpt-4o'
  max_tokens: 300

# Image resize limits before sending to OpenAI (default: 1024x1024)
AiAltText\Service\AltTextGenerator:
  max_image_width: 1024
  max_image_height: 1024

Custom Prompt (SiteConfig)

The AI prompt can be customized directly in the CMS:

Go to Settings in the CMS
Click on the AI Alt Text tab
Enter your custom prompt in the text field
Save

The custom prompt allows you to:

Set the output language directly (e.g., "Write in German" or "Schreibe auf Deutsch")
Customize the style and length of generated alt texts
Add specific instructions for your content type

Example custom prompt (German):

Schreibe einen prägnanten, beschreibenden Alt-Text für dieses Bild auf Deutsch.

Regeln:
- Länge: 80-160 Zeichen, kürzer bei einfachen Bildern.
- Sei spezifisch und beschreibend.
- Beginne nicht mit "Bild von", "Foto von" oder ähnlichen Phrasen.
- Keine Marketing-Sprache.
- Gib NUR den Alt-Text zurück, nichts anderes.

Leave the field empty to use the default English prompt.

License

BSD-3-Clause

moritz-sauer-13 / silverstripe-ai-alt-text

Maintainers

Details