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How to Highlight a Scanned PDF Effortlessly? 3 Easy Ways With Guide

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 on Windows and Mac With UPDF?

If you have a scanned PDF or image-only PDF and want to highlight the text on Windows and Mac, in such a scenario, UPDF can help you out. You can highlight the scanned PDFs easily using this tool after making them editable via the OCR feature integrated into the UPDF. the OCR feature in UPDF supports over 38 languages. And it has customization features that can help you get better results. It offers three layout options: text and pictures only, text over the page image, and text under the page image. These layout options let you get the content you want to highlight.

After making the scanned PDFs highlightable, you can choose the color you like for the highlighter and use the continuous highlighting features to highlight the PDF in the same color or style continuously. Moreover, you are allowed to add notes to the highlighted contents with sticky notes, text comments, text boxes, and callouts. It also has other annotating features like strikethrough, underline, squiggly, pencil, stickers, and more. You can click the below button to use this tool and follow the below guide to highlight scanned PDFs.

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Way 1. How to Highlight Scanned PDF on Mac and Windows Without Continous Highlighting

If you only need to highlight one part in the scanned PDF or want to highlight the content in different parts with different colors, you can 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 Highlight 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 click on the "Highlight" feature, select the color you like, and draw on the contents 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

Way 2. How to Highlight Text in a Scanned PDF Document on Windows and Mac With Continous Highlighting

If you prefer highlighting the text in a scanned PDF with the same color in different parts in PDF, you can follow the below guide.

Step 1. Same as the above guide, you need to click the below button to download UPDF on your Windows or Mac computer, open scanned PDF with UPDF, perform OCR on the scanned PDF and now the OCRed PDF is open in UPDF.

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Step 2. Now, you need to double-click on the "Highlight" icon to enable the continuous highlighting feature. Move your mouse on the highlight icon to select the color you prefer, and now, you can draw on different parts to highlight the content with the same color.

How to Highlight Text in a Scanned PDF Document on Windows and Mac With Continous Highlighting

Want to use UPDF to highlight scanned PDFs now? Tap on the "Free Download" button below and use it.

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You may be surprised by UPDF as it has many other features except highlighting scanned PDFs. You can watch the below video guide or read this UPDF review article to learn more about it.

Also Read: Underline PDF Like a Pro

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

Yes. 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 and the price is very expensive.

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?

Yes. You can highlight scanned PDFs online. There are many tools that can used. Here, we pick up SmallPDF as it is easy to use and has many other features. However, you should note that you cannot use the highlight features to highlight scanned PDFs online as scanned PDFs cannot be editable. So you need to use its rectangle shape feature. Here is the guide.

Step 1. Visit the SmallPDF editor, and upload the scanned PDF to SmallPDF.

Step 2. Now, you are in the Markup part. Go to select "Shape" > "Rectangle".

Shape feature in smallPDF

Step 3. You can find the fill and border color options. You can click on the fill color to choose one, then, drag the slider to adjust the opacity of the fill color. Once it is what you like, you can do the same operations for the border color. When it is done, click "Export" to save the highlighted scanned PDF.

Adjust the highlighted color in scanned PDF with 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 AcrobatSmallPDF
PricingYearly Plan: US$39.99
Perpetual Plan: US$69.99 
ProsThe oldest product in the PDF industry
Complete PDF features
The oldest product in the PDF industry
Complete PDF features
Don't need to install software
ConNew product on the marketInability to edit the text in PDF FileUnstable and unsafeInability 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.

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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.

Q4. How to Remove Highlights from Scanned PDFs?

If your scanned PDFs have highlighted contents, you need to use UPDF to remove them. The first step is to use OCR to make them editable, then, go to the "Comment" part and you can right-click on the highlighted contents to select "Delete" to delete the highlighted effects. If this method does not work, you can use the shape feature to cover the highlighted contents, then, use add text to replace it with contents that are not highlighted.


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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