Best Practices for Scanning Documents for OCR

The quality of your scan directly determines the quality of OCR output. Follow these best practices to maximize text recognition accuracy.

Scanner settings: Set resolution to 300 DPI minimum for standard printed text (10–12pt). For small print or documents with fine detail, use 400–600 DPI. Always scan in color or grayscale — never in pure black-and-white (1-bit) mode, which loses anti-aliasing detail that OCR engines use to discern character edges.

Document preparation: Remove staples, paper clips, and sticky notes. Flatten folded pages. If the document has writing on both sides and the paper is thin, place a black sheet behind it to prevent bleed-through from the reverse side.

Alignment: Place the document straight on the scanner bed. Even a few degrees of rotation reduces OCR accuracy. Most scanning software includes auto-deskew, but manual alignment is more reliable.

Output format: Save scans as TIFF or high-quality PNG for the best OCR input. Avoid JPG for document scans — the compression artifacts around text edges confuse OCR engines. TIFF is ideal for multi-page documents; PNG works well for single pages.

Post-scan processing: Crop tightly to the text area, removing margins and blank space. If the image is dark or yellowed, adjust brightness and contrast in an image editor before running OCR. Converting to pure grayscale often improves results by removing color noise.

Testing: Run OCR on a sample page before scanning the entire document. Check for common errors like 'rn' recognized as 'm', 'cl' as 'd', or numbers confused with letters. Adjust scanner settings if accuracy is below 95%.