AI-Powered Slide Accessibility Tool (PPT-Alt-Text)

This utility automates the generation of descriptive alt-text for images in PowerPoint presentations. It uses the Gemini 2.5 Flash model to analyze visual content and provide descriptions compatible with screen readers.

Unlike standard accessibility tools, this script uses a recursive deep-scan to identify and tag images that are:

• Copy-Pasted: Standardizes images that PowerPoint containerizes during direct paste operations.
• Nested in Groups: Drills down into grouped objects, common in chemical structures and complex diagrams.
• Layout Placeholders: Captures images dragged into pre-set university template boxes.

Prerequisites

1. Python 3.x
2. Google Gemini API Key: Obtainable via Google AI Studio.
3. Required Libraries:

pip install python-pptx google-genai python-dotenv

Installation and Setup

Option 1: Direct Download (Easiest)

1. Click on the PPT_AltText.py file in the list above.
2. Click the Download raw file button (the downward arrow icon) to save it to your computer.
3. Place the file in the folder where you want to run your accessibility jobs.

Option 2: Clone via Git

git clone https://github.com/walternmoss/AI-Powered-Slide-Accessibility-Tool-PPT-Alt-Text-.git
cd AI-Powered-Slide-Accessibility-Tool-PPT-Alt-Text-

Final Configuration

Create a file named .env in the same directory as the script and add your API Key:

GOOGLE_API_KEY=your_key_here

Note: The .gitignore file in this repository is pre-configured to ensure your .env file is never uploaded to the public site.

Usage

Safety Recommendations

It is highly recommended to work on copies of your files. While the script creates a new file with an _Accessible suffix, maintaining an untouched original is best practice to prevent any accidental data loss.

Single File

Run the script by providing the path to a PowerPoint file. Use the -d flag to specify your discipline (e.g., Biochemistry, History) for technical accuracy.

python PPT_AltText.py Your_Lecture.pptx -d "Biochemistry"

Batch Processing

To process an entire folder of presentations, provide the directory path:

python PPT_AltText.py ./Lectures_Folder -d "Biochemistry"

• Output: Generates a new file with the suffix _Accessible.pptx.
• UI Visibility: The script writes to three separate internal XML locations (name, description, and the descr attribute) to ensure descriptions appear correctly in the PowerPoint Accessibility Pane.

Technical Notes

• API Credits and Quotas: This tool uses the Gemini API. If you are using a free tier, you may hit rate limits during large batch jobs. If you have a paid tier, processing hundreds of high-resolution images across many decks will consume credits. Monitor your Google AI Studio console to track usage and costs.
• Privacy: This script sends image data to Google's API for processing. Avoid using it with slides containing sensitive student data.
• Verification: While highly accurate, always review descriptions of complex metabolic pathways or specific data plots.
• Lock Files: Ensure PowerPoint is closed before running the script. The tool needs to modify the internal XML; if PowerPoint is open, it creates a "lock file" (starting with ~$) that can cause the script to fail.

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