PreP-OCR: A Complete Pipeline for Document Image Restoration and Enhanced OCR Accuracy
To address low OCR accuracy caused by degradation in historical document images, this paper proposes a two-stage end-to-end optimization framework. In the first stage, a U-Net–based image restoration model is trained on a synthetically generated multi-degradation dataset to jointly optimize visual clarity and linguistic consistency. In the second stage, a semantic-aware ByT5 model performs post-OCR error correction, enhanced by a multi-directional block extraction and fusion mechanism tailored for large-format documents. The key innovations include the first joint optimization of image restoration quality and text semantic consistency, and the construction of the first cross-lingual (English/French/Spanish) synthetic dataset for historical text. Evaluated on 13,831 pages of real historical documents, the framework reduces character error rate by 63.9–70.3% over baseline OCR systems, demonstrating substantial improvement.