What is OCR? How Computers Read Text from Images
By TellPDF Team
Have you ever opened a scanned document or a photo of a printed page and found that you couldn't highlight text, search for keywords, or copy a single word? That happens because a scanner or smartphone camera doesn't produce text; it creates a grid of colored pixels. To a computer, a scanned contract is no different than a digital photograph of a sunset.
Optical Character Recognition (OCR) is the technology that bridges the gap between visual image pixels and digital text. An OCR engine analyzes a document image in steps. First, it cleans up the image by enhancing contrast and straightening tilted pages. Next, it breaks the image down into lines, words, and individual character glyphs. By comparing the geometry of these pixel shapes against learned letter patterns, the system identifies characters and converts them into real digital text.
Modern OCR engines go a step further by preserving document layout. Once the text is recognized, the system constructs an invisible text layer directly on top of the original image pixels, matching the exact coordinates of every word. This allows you to search, highlight, copy, and interact with a scanned document as if it were natively created on a computer, all while preserving the visual appearance of the original paper.