Here comes the question: how do we identify the characters within a scanned PDF and make the PDF text selectable? The most straightforward and efficient method is to utilize OCR tools. This post will revolve around several OCR tools used to optimize a PDF document.
What Is OCR Technology?
First things first, we need to straighten out what OCR technology is. OCR stands for Optical Character Recognition, which is a process where PDF programs are able to transform images of text into a machine-readable format. This widespread technology identifies the unsearchable content and extracts the text from an image-only PDF or scanned PDF.
How to OCR a Scanned PDF with Desktop Software
SwifDoo PDF is a versatile PDF desktop program on Windows OS. As a multitasker, it can help with PDF editing, annotating, password protecting, and converting. In the newest 2.0 version, SwifDoo PDF incorporates a brand-new feature - OCR (Optical Character Recognition) to assist users in managing digital documents.
Let’s take a look at how to run OCR on a PDF with SwifDoo PDF:
Step 1: Download and install SwifDoo PDF from the official website or Microsoft AppSource;
Step 2: Launch the program and click on OCR in the tab Edit;
Step 3: In the Recognize Document window, users can choose how to OCR the current PDF document and convert the PDF into: a document with text and images; text with original formatting; searchable text and images but non-editable; or a pure text;
Step 4: When you decide the output option, feel free to specify page range to perform OCR if needed. Once ready, hit the OK button to start OCRing the PDF.
Some users may wonder how to tell whether a PDF file is a scanned PDF or image-only PDF and thus requiring OCR, here're two solutions:
Click "Edit". If there is a window showing no editable content with the PDF, it is a scanned PDF;
Or users can perform PDF conversion tasks by clickin "Convert", such as PDF to Word conversion. SwifDoo PDF will mark out the nature of the PDF next to the file name just as the screenshot demonstrates.
If you need to convert a scanned PDF into an editable Word document or text file, the conversion results may disappoint you as the Word document after conversion is full of errors and wrong formatting. You can, however, optionally try OCRing the PDF and the OCRed PDF will be saved in the same local folder as that of the original PDF.
Soda PDF is a powerful PDF tool which aims to make PDF-related tasks easier. This Windows-based PDF program enables users to edit, reorder, annotate, and secure PDFs.
Step 1: Download and install Soda PDF on your PC;
Step 2: Start the program to open the scanned PDF;
Step 3: Select OCR or click on any page of the image-only PDF to trigger OCR mode. When you see the hanging menu bar, choose OCR Auto and the PDF page will be converted into selectable and editable text.
Soda PDF provides two OCR modes: OCR Auto and OCR Manual. The main difference of these two modes is that the latter one enables users to decide how the OCR engine interacts with your images while the auto mode will automatically look for and scan the next Image as well. The manual recognition is capable of detecting text, images, or tables. Any area inside this red box will be interpreted as text.
Since scanned PDF is made of layers of images, Soda PDF provides “Crop” tool to allow for trimming of the PDF page. In the meantime, users can move or copy any page for personal use by right clicking on the PDF image.
Soda PDF is available both on Windows OS and web. These two versions share the same user interface and features without any other differences.
How to OCR a Scanned PDF on macOS
Cisdem PDF Converter OCR for Mac
For macOS users who need to handle scanned PDFs, things were more complicated until we found Cisdem. Cisdem and relevant products are created for Apple computers, including the center of this section - Cisdem PDF Converter OCR for Mac.
Cisdem PDF Converter OCR integrates a full set of useful tools to deal with PDF-related tasks, such as how to OCR a scanned PDF on macOS, how to combine PDF files, and how to batch convert PDF files. Without further description, let’s get down to the business:
Step 1: Import the image-only PDF to the workstation by dragging or dropping the file on the interface, clicking + button, or selecting File > Add file;
Step 2: Select the language of the original PDF document for an improved recognition accuracy. Cisdem now supports 27 languages which can meet basic need of users;
Step 3: At the Converter page, tick the OCR box to perform OCR on the current PDF. Please be aware that there are two OCR buttons. The one next to the Range is only for the selected PDF while the other one is to apply OCR on all uploaded PDFs.
Step 4: Select to DOCX in the output format box and hit the Convert button. Then choose the output folder and click on the Save to finalize the process of OCRing a PDF to a Word file on Mac.
Additionally, users can choose “Advanced Settings” to manually adjust the recognized text, images, or tables.
How to OCR a Scanned PDF Online
For someone who prefers a web-based PDF OCR tool, this cloud storage platform may be a good option. It’s hard to imagine Google Drive would be able to perform such a task. The truth is, from the Google Drive Help Center, this online application is capable of converting PDFs and photo files to text.
Step 1: Log in your Google Drive account and click on the New button below the Drive icon;
Step 2: In the drop-down menu, choose File upload to import a local PDF document to the workspace;
Step 3: Right click on the uploaded PDF and choose Open with > Google Docs to convert the scanned PDF into an editable Word document. When you are directed to Google Docs page, you are free to output the Word file locally.
The process of OCRing a PDF document with Google Drive is not complicated though, there are some limits of this free online OCR tool before you start out:
File size: Your file (.jpg, .png, .gif, or PDF file) should be kept within 2 MB;
Resolution: Text should be at least 10 pixels;
Orientation: Documents should be right-side up.
Font styles: Make sure the font in your file is common, such as Arial or Times New Roman.
OCR Space is an online OCR service provider free of charge. At the same time, this useful tool is an open-source program which provides free OCR API key for developers. As a free tool, OCR Space simplifies the converting process and hence users only need to make a couple of clicks to run OCR on a PDF. Let’s dive into the process of how to OCR a PDF document online
Step 1: Enter the URL on the search bar and select Choose file to upload the PDF;
Step 2: Choose the language of the original PDF document and tick the recognition or orientation if needed. Besides, users are enabled to create searchable PDF by changing how the PDF is displayed in Create Searchable PDF;
Step 3: Once ready, press the Start OCR! button to output the scanned PDF into a selectable DOCX document.
In final words, online OCR tools are free to use but their OCR capabilities may be overshadowed by desktop software, particularly when it comes to an image-only PDF written in multiple languages (textbook for instance). However, desktop OCR programs only provide limited free trials, when SwifDoo PDF can provide 30-day free trial.