OCR

OCR (Optical Character Recognition) turns a picture of text into real, selectable text. A scanned page or a photo of a document is, to a computer, just a grid of pixels: you cannot search it, copy from it, or have a screen reader read it. OCR analyzes those pixels, recognizes the letters and words, and produces an actual text layer.

The usual result is a searchable PDF: the page still looks exactly like the scan, but an invisible text layer sits underneath, so you can highlight, search, and copy as if it had been typed. This is what makes archives of old scans usable instead of being dead images.

Accuracy depends on the input. Clean, high-contrast scans at around 300 DPI read far better than blurry phone photos. Once OCR has run, a stack of scanned pages becomes something you can actually search through and pull text out of.