RAG for PDFs with tables and images: what breaks and how to fix it

Plain-text chunking destroys tables and ignores images. A practical pipeline for PDFs that actually contain the data your users are asking about.

Presenting to a room
Presenting to a room

Most RAG tutorials assume clean paragraphs. Real documents — invoices, syllabi, lab manuals — carry tables and figures that a naive text extractor flattens into unreadable rows of numbers.

Extract structure, not just text

Use a layout-aware parser that separates tables from prose and keeps row/column relationships (as markdown tables or JSON), rather than concatenating cell text into one blob. Store each table as its own chunk with a caption describing what it contains.

Images need a caption before they need an embedding

Run a vision-capable model once at ingestion time to generate a text caption of each figure, then index the caption alongside the surrounding paragraph. Retrieval then works off text even though the original content was visual.

  • Keep the table's caption or preceding sentence attached to it — a bare table with no context retrieves poorly.
  • Store page number and figure number as metadata so citations point somewhere useful.
  • Test retrieval with questions that specifically require a table value, not just prose facts.

Related: an OCR pipeline for turning PDFs into searchable text and document AI for invoice extraction.

RAGPDFDocument AI
Pranjul Rathour
Pranjul Rathour
GenAI Engineer · Kanpur, Uttar Pradesh, India

GenAI engineer and AI product builder with 2+ years shipping production-grade AI systems: RAG pipelines, fine-tuned LLMs, hybrid retrieval and multi-modal apps across vision, speech and OCR, architected end to end from ingestion to deployment. Leads engineering for SCULT INDIA's 14-member team, founded the 500+ member TechVerse Enclave community and has mentored 200+ students. Three hackathon first prizes: Changethon 2025 (IIT Roorkee), Product Genesis at Vividhotsava 2025 (CSJMU Kanpur) and BYTEBATTLE (MeetKats).

Open to GenAI roles, hackathon judging, mentorship sessions and guest talks at colleges. Email pranjulrathour41@gmail.com.

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Pranjul Rathour, GenAI engineer in Kanpur