office-thumbnail-skill

What I do

I convert Office files to images for visual analysis — thumbnail grids, individual page images, or PDF intermediates. This is the visual-review companion to the OOXML editing and slide-generation skills.

• Thumbnail grids — multi-page Office files → single grid image for quick overview (thumbnail.py)
• PDF conversion — Office file → PDF via headless LibreOffice (soffice.py)
• Image conversion — PDF pages → individual JPEG/PNG images via Poppler

When to use me

Use this skill when the user wants:

• "Show me thumbnails" / "visual analysis of this deck"
• "Convert slides to images"
• "Generate a visual grid for review"
• Any task needing to visually inspect Office document pages

Also used internally by:

• pptx-specialist-subagent Stage 5 (visual verification via image-analyzer-subagent) — renders each generated slide to PNG for vision-model sizing verification
• code-review-subagent / uiux-reviewer-subagent — visual evidence capture

Prerequisites

• LibreOffice (soffice) — headless PDF conversion

  sudo apt-get install libreoffice          # Debian/Ubuntu
  winget install TheDocumentFoundation.LibreOffice   # Windows (or use WSL)

• Poppler (pdftoppm) — PDF to image conversion

  sudo apt-get install poppler-utils        # Debian/Ubuntu
  # Windows: use WSL, or a poppler build via your package manager

• Python 3.9+

Workflow

Thumbnail grid generation

python scripts/thumbnail.py presentation.pptx [output_prefix]

• Creates thumbnails.jpg (or thumbnails-1.jpg, thumbnails-2.jpg for large decks)
• Default: 5 columns, max 30 slides per grid (5×6)
• Custom columns: --cols 4 (range 3-6)

Convert to PDF (intermediate)

python scripts/soffice.py --headless --convert-to pdf presentation.pptx

The soffice.py wrapper handles the AF_UNIX socket restriction in sandboxed VMs.

Convert PDF to images

pdftoppm -jpeg -r 150 presentation.pdf slide

Creates slide-1.jpg, slide-2.jpg, etc.

Scripts

Script	Purpose
thumbnail.py	Generate visual thumbnail grids from any Office file
soffice.py	LibreOffice wrapper — handles sandbox AF_UNIX socket restrictions

Use cases

• Template analysis: Quickly understand slide layouts and design patterns
• Content review: Visual overview of entire presentation
• Quality check: Verify all slides are properly formatted
• Visual verification: Render generated slides for image-analyzer-subagent sizing checks (BT-142 Phase 2.4b)
• Documentation: Include slide images in reports or PR reviews