PDF Transparent Text Overlay App (OCR)

This app adds a "searchable transparent text layer" to a PDF via OCR, without materially changing its visual appearance.

1. Screen Layout

• Drag-and-drop area / list
  Drop PDF files or folders. Dropping a folder lists all PDFs directly inside it. Duplicate files are prevented.
• OCR language (radio buttons)
  English / German / French / Spanish.
• Start / Clear List / Close
• Status display
  Shows progress: "Checking", "Processing", "Skipped", etc.

2. Existing Text Detection and Skip

• After starting, each PDF is checked for whether a sufficient text layer already exists.
• If detected, you are asked whether to run additional OCR; declining skips that PDF.

3. Output and Notes (Important)

• Processing overwrites the source PDF. Copy the PDF first if needed.
• Japanese transparent text is not supported (spaces inserted between characters make the text unsearchable). Use "Extract text and display as HTML" in PDO Explorer instead.