Discover How to Highlight Text in Scanned PDF Effortlessly

Nowadays, highlighting scanned PDFs has become a necessity in various fields such as education, research, or business and corporate work. So, users highlight the scanned PDFs mostly to emphasize key points or terms and conditions that require users' attention.

If you have been searching for how to highlight scanned PDFs but are unable to find a way, this guide has you covered. Start reading this article to find out the three best tools to help you highlight scanned PDFs without any complex or time-consuming process.

Part 1. How to Highlight Text in Scanned PDF?

If you are a person whose daily work routine requires dealing with several PDFs for highlighting purposes, in such a scenario, UPDF can help you a lot in lowering the workload. UPDF is one of the best multi-dimensional tools that offers the best PDF highlighting and various other annotation features.

Users can even highlight the scanned PDFs easily using this tool after making them editable via the OCR feature integrated into the UPDF. After this, users can even perform various markup features, including underlining and strikethrough, with the help of this tool. However, the OCR feature in UPDF supports over 38 languages and helps you recognize the text in scanned PDFs to highlight them in a much clearer way.

Continuing this, this feature even offers three layout options: text and pictures only, text over the page image, and text under the page image. These layout options let users fulfill the need to highlight scanned PDFs more comprehensively.

Steps-by-Step Instructions to Highlight Scanned PDF Using UPDF

In order to use the OCR feature of UPDF to highlight scanned PDFs, have a look at the following detailed steps to help you easily perform this task:

Step 1: Launch UPDF on Your System and Import the Scanned PDF File

Download and launch the latest UPDF version, and ensure your scanned PDF is saved on your device. From the tool's main interface, hit the "Open File" option and import the scanned PDF file.

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how to highlight scanned pdf open file

Step 2: Enter OCR Mode and Customize

Besides this, in the main UPDF window, click on the "Recognize Text Using OCR" button from the right-side toolbar.

There, an extended menu of options will appear on the left side. The most important thing here is to choose the layout of scanned PDFs carefully. Access the "Layout" drop-down menu and choose from three options to retain text and images, make text go under the image, or keep it over the page.

After that, customize other settings if needed, such as "Document Language," "Image Resolution," and "Page Range" required for highlighting purposes.

Hit the "Perform OCR" button and save the file on your system.

how to highlight scanned pdf peform ocr

Step 3: Select the Comment Option for Accessing Different Features

Next, your editable file will automatically open after the OCR is performed. Head to the left side toolbar and choose the "Comment" icon. A menu bar will now be revealed on the top side of the tool, from where you can choose different tools to highlight PDFs.

First, you can directly choose the "Highlight" feature to highlight text with customized colors. Second, you can add "Sticky Notes" to your highlighted text to note any key points. You can also specify the reasons behind why you highlighted this section. At last, save your file to your system hassle-freely.

how to highlight scanned pdf highlight

Using this AI-powered tool with the most advanced highlight feature helps you perform various annotation functions on your PDF. Users can also turn the scanned PDFs into an editable format in just a few steps to highlight them productively. To get all these features, tap on the "Free Download" button below and use this tool to highlight your scanned PDFs professionally.

Part 2. Can I Highlight Scanned PDFs in Adobe Reader?

Adobe Reader is the best tool to help you annotate scanned PDF files by highlighting them for official use. This markup tool helps businessmen efficiently manage their PDFs. Users can perform several functions, including underlining and highlighting text in PDF documents. However, you need to remember that the highlight scanned PDFs feature is only available to paid users.

Using Adobe, while highlighting the scanned PDF, users can easily change its color and even the opacity. Once you have access to the paid version, then follow this detailed guide below to understand how the OCR feature of Adobe Acrobat works so you can use it without any difficulty:

Step 1. Initiate the process by launching Adobe Reader on your computer and then importing your PDF file. Select the "Scan & OCR" option from the main window's right-side tool panel for access to different settings.  

how to highlight scanned pdf ocr adobe

Step 2. Click the "Recognize Text" option on the top panel to access a drop-down menu. Afterward, choose the "In this File" option to access different settings. Here, you can add a custom page range and language to your PDF. Once the necessary settings are done, hit the "Recognize Text" button to perform the OCR conversion.

how to highlight scanned pdf recognize text button

Step 3. After performing OCR, head toward the "Comment" option from the right-side tool panel and tap on it to access the further annotating settings. Select the "Highlight" option from the top toolbar to highlight the scanned PDF. There, you can also adjust the highlighter color and its opacity if needed.

how to highlight scanned pdf annotate

Part 3. Can I Highlight Scanned PDF Online?

There are a lot of online tools available that help you highlight scanned PDFs and have a number of different annotation features to note down key points for the highlighted. Many tools online claim to be the best tools with the most accurate OCR and highlighting features. However, this isn't always the case, as most of these online lack many features at most of the points.

You can even take an example from the screenshot shown below of the Smallpdf tool. It can be clearly seen that this tool cannot highlight the scanned file as it doesn't have any built-in OCR feature. So, in this case, users can't always rely on these online tools. In this case, to help you avoid any hassle, we have explained UPDF above, which offers the best OCR and highlighting features.

how to highlight scanned pdf smallpdf

In addition, before using any tool with a highlighting feature, ensure they are secure so that your sensitive data is saved and doesn't get corrupted. Moreover, to help you avoid this complication, we recommend you download and use UPDF to help you highlight scanned PDF files professionally. Furthermore, the OCR technology in this tool is much more advanced and supports over 38 languages.

Part 4. Comparing the 3 Methods to Highlight Scanned PDF

The above-discussed PDF tools help you to highlight scanned PDFs and are available globally to help users enhance and manage their workloads. However, choosing the right tool is quite a challenging task, and for that, we have made a comparison table below to find out the best tool:

MetricsUPDFAdobe AcrobatOnline Tools
PricingYearly Plan: US$29.99
Perpetual Plan: US$49.99 
US$239.88/yearPrices Vary
ProsIt has AI-integrated tools.Provides Cross Platform SupportOutstanding Customer ServiceUser-friendly InterfaceThe oldest product in PDF industryComplete PDF featuresDon't need to install software
ConNew product on the marketCan't use its premium features until paidToo expensiveComplex user interfaceInability to edit text in PDF FileUnstable and unsafe
OCR Results Rating4.8/54.6/54.3/5
UI Rating4.9/54.5/54.2/5

After analyzing the table discussed above, we can conclude that UPDF is the most fantastic tool for highlighting scanned PDFs. Having the OCR result and UI rating, UPDF stands out among its competitors. Moreover, this tool is the most stable, and even the pricing of this tool is 12% of what Adobe Acrobat offers. To get all the features of this tool, hit the "Free Download" button below and start using UPDF right away.

Part 5. FAQs on How to Highlight Scanned PDF

Q1. Can I highlight a scanned PDF document?

Yes, you can highlight scanned PDF documents with the help of UPDF. For that, import the scanned PDF via "Open File." Now, in the right-side toolbar, hit the "OCR" icon, customize settings, and tap "Perform OCR." Now, select "Comment > Highlight" to highlight the required part.

Q2. Why can't I highlight a scanned PDF?

One of the main reasons scanned PDFs are not highlighted is that you cannot select text in scanned PDFs. That is why you must first perform OCR on your PDF to highlight text in such PDFs. After this, you can easily highlight scanned PDFs.

Q3. Why does my PDF not allow highlighting?

There are many explanations for which you might not be allowed to highlight the PDF. For example, if your PDF is password protected, you will be able to perform any action on it once you have its password.


Nowadays, every person needs to perform different functions on long-detailed PDFs and other documents. Therefore, to help these people in resolving their PDF annotating issues, several tools have been introduced in the market. But one of the most prominent tools with good ratings and helpful features accessible on the internet is UPDF.

It provides a comprehensive system to highlight scanned PDFs, which eases the overall system of analyzing a scanned file. Thus, without wasting any time, download this PDF highlighter and purchase its premium plan to start editing your files without worry.

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