Making PDFs Accessible for Visually Impaired Users (and Findable for Everybody Else)

We treat documents released under the Dutch Freedom of Information Act as FAIR scientific data and find that they are not findable nor accessible, due to text malformations caused by redaction software. Our aim is to repair these documents. We propose a simple but strong heuristic for detecting wrongly OCRed text segments, and we then repair only these OCR mistakes by prompting a large language model. This makes the documents better findable through full text search, but the repaired PDFs do still not adhere to accessibility standards. Converting them into HTML documents, keeping all essential layout and markup, makes them not only accessible to the visually impaired, but also reduces their size by up to two orders of magnitude. The costs of this way of repairing are roughly one dollar for the 17K pages in our corpus, which is very little compared to the large gains in information quality.