With optical character recognition (OCR) technology, OCR software automatically extracts text from any scanned PDF or image file and OCR converts it to a searchable PDF file. With OCR software, you can transform a scanned PDF of a paper document into a text-searchable PDF document. This new OCR searchable PDF is like an image containing text data, that you will be able to search for a specific keyword. When we read a document, our brain recognizes a character by analyzing the patterns and compare them against the pre-learned alphabet set. An OCR software application is trying to do the exact same. An OCR software reads the text pixels from a scanned image and compares it against a pre-trained dataset. Once the text is recognized, it is added as a hidden layer in the scanned PDF. This new "sandwiched PDF" file is popularly known as a searchable PDF.