Where to view PDF annotations and how to open and use annotation mode

Key points of this article

Most PDF annotations are in the annotation list or annotation panel. Searching the list first and then looking at the page marks is much faster than searching page by page.
When you cannot see the annotations, first check the display switch and then confirm whether the file has been flattened. The flattened mark is only the page content.
The annotations on the scanned document are images and cannot be clicked like ordinary annotations. You need to confirm them first before deciding whether to perform OCR.
Save a copy before modifying to avoid being unable to restore the other party's comments after working on the original.

I received a PDF with revision comments, but when I opened it, I couldn’t find the red boxes, highlights or sticky notes, only the main text. In most cases, it is not that the file has lost content, but that the comments are not displayed, or are hidden in a certain panel of the reader. This article is written for such readers to explain where PDF annotations are usually located, how to open them for viewing, and in what order they should be checked if they cannot be seen.

After reading this article, you can determine whether there are comments in your file, find the comment list, check the author, page number and content one by one, and protect it before modifying it. What this article talks about is a general approach. Different readers may have different panel names and locations. If you encounter differences, just look for them according to their functional meaning.

Where can I view PDF annotations? One sentence conclusion

In most cases, there is no need to "enter" a mode specifically. You can see all the content by opening the annotation list and confirming that the annotations are displayed. The comment list usually exists in the form of a sidebar or panel, listing the author, page and text content of each comment.

your situation	Recommended practices	reason
I can see marks on the page and want to read them one by one.	Open the comment list or comment panel and read in order	The list will focus on the author, page number and content
There is nothing on the page, but the other party said it has been commented	Check the switch to show comments, and then confirm whether the comment layer is turned on in the reader	Annotations may be hidden, but it's not impossible
The mark has been turned into a normal graphic or text and cannot be selected individually.	View the normal page content instead of looking for the annotation list	The annotation is flattened and becomes part of the page.
Handwritten annotation on scanned document	First try to select the text to determine the type, and then decide whether to recognize it or not.	Annotations on scans are themselves images
Need to continue to modify based on comments	Save a copy first and then work on the copy	Protect originals and facilitate comparison and return

Before you start: Confirm these points first

Make three judgments before taking action, which can save a lot of time in trying back and forth.

Confirm that the file is an "annotation-aware" PDF. Comments are independent objects that can be individually selected, clicked, or listed. If there is no response when a marker is clicked, and the entire page moves together as one image, it is likely that it has been flattened and there will be no corresponding entry in the list.
Confirm the reader you are using and its panel position. Different readers place comments in different locations, some in the sidebar, and some in the "Comments" or "Comments" related options on the toolbar. If you can't find it, you can search for words like "annotation", "annotation" and "comment" in the view or tool menu.
Determine whether the page is text or picture. Try to select a text with the mouse. If you can select it, it means it is a text page; if you cannot select it, it is probably a scanned copy or a picture. The annotations and text on the scanned document are all images, so the list function may not be used and requires additional processing.
Back up the original first. There may be multiple versions sent by the other party. Keep an original copy of the file before modification so that you can roll back when problems arise and make it easier to check later using the comparison function.

Steps to open the comment list in the reader

The following is a general process that works with most desktop software that can view PDFs. If you use the OmniDoc desktop client, you can open the file after downloading it from download.omnidoc.top and search in the same way.

Open PDF files with a reader. Don't rush to edit yet, just browse. Make sure you opened the file they sent, not the old version you saved earlier.
Observe page edges and toolbars. Look for icons like "Comments," "Comments," or similar icons, which are usually located on the left or right sidebar, or possibly in the top toolbar.
Open the comment list. Each item in the list should display the author, page number, and content summary. If the list is empty but there are labels on the page, go back to step four to check the display settings.
Check the display switch. In the view or tool menu, find the option related to displaying comments and confirm it is enabled. Some readers allow you to control different types such as highlights, notes, and hand-drawn drawings, requiring class-by-category checks.
Click the item in the list. The reader should jump to the corresponding page and locate the annotation location. Being able to jump means the annotation corresponds to the page.
Record or verify item by item. If you need to organize and revise your suggestions, you can record them by page number and content in a separate document. When organizing, refer to the original text on the page to avoid misunderstandings caused by only reading the abstract.
If editing is needed, save a copy first. Make changes to the dungeon, keeping the original untouched. If you want to modify paragraphs at the text level, the PDF editor in the OmniDoc desktop client supports direct editing of paragraph text.

After completion, check each item one by one

After reviewing the annotations or making modifications on the copy, check item by item in the table below to confirm nothing is missed.

Inspection items	How to see it	What should you do if there's a problem?
Annotation quantity	Check whether the number of listings roughly matches the number of markers on the page	If inconsistent, check the display switch or confirm that the marker has been flattened
Page numbers and locations	Click on the list entry to see if it jumps to the corresponding page	If you can't skip it, the file may have been altered, so you need to ask the other party for the original version
Authors and content	Check whether the authors and main text in the list are complete	Most missing content is lost during export, so you need to retrieve the original
Scanned copy annotated	Can you select text, and are the annotations just images?	When it is an image, OCR can be performed first, then the text can be searched and the recognition result verified
Whether the original document has been altered	Is there a difference compared to backup?	Use the comparison function to see the differences between the two files; if there are mistakes, use backup to revert

OCR recognition may have errors; for key numbers, personal names, and technical terms, please verify them verbatim with the original page.

🎯 Which method suits you?

Just want to read the other person's opinion: Open the comment list, read through the page number, and note the key points in your own document; no need to change the original.
You need to reply and revise the main text item by item: First, save a copy, make corrections on the copy according to the annotations, then compare with the original to confirm the scope of changes.
Received is a scanned copy or photo-format PDF: First, check if the text can be selected. Selectable ones are processed as regular text; If you can't select one, you need to perform OCR before searching and organizing.
You need to return the changes to the revision: Before exporting, check again to see if the annotations are still visible. If the other party asks to keep the comments, do not flatten all the marks before sending them.

❓ Frequently Asked Questions (FAQ)

1. When I open the PDF, I can't see the comments—is it because there are no comments in the file?

Not necessarily. Comments may be hidden, the reader's display switch may not be turned on, or the file may have been flattened during export. First, check the display settings, then confirm whether page markers can be selected separately.

2. Can annotations be searched like text?

Whether searchability is available depends on whether the annotation contains recognizable text. Handwritten annotations and graphic markers cannot be searched directly; notes with text are usually found in the annotation list.

3. Why did someone else's annotation become a regular graphic on my side?

This is most likely because the comment was flattened into the page during export, or your reader does not support such comments. Requesting a version with reserved comments from the other party usually solves the problem.

4. How can I check the annotations on the scan?

The annotations on scans are images and cannot be opened in the list one by one like regular annotations. You can first view the page directly, then use OCR to identify and verify the results when searching or organizing text.

📝 Summary

PDF annotations are usually in the comment list or comment panel. If you can't see them, first check the display switch to determine whether the file has been flattened or is a scan. By following the steps in this article, you can clearly understand how to open, use, and view PDF annotation mode all at once.

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