Parsing and Cleaning: What Quietly Breaks When PDFs, Tables and Scans Become Text
When documents become text, what breaks usually doesn't throw an error: multi-column paragraphs joined in the wrong order, merged table cells flattened, headers and footers mixed into the body, OCR typos in scans, images and strikethroughs gone. High OCR accuracy doesn't mean good RAG either: in one study, documents with strikethroughs and color marks scored 82.9% on OCR but only 52.8% on question answering. Chunking matters more than switching tools: from the same conversion output, chunking by heading hierarchy with the heading path attached raised table questions from 66.6% to 99.8%. So always spot-check parsed output against the originals for these failure types.