How to lock a frame image in a pdf document?

According to the query results of academic reference network.

1. Open the PDF document with the frame picture to be locked, select the View tab in the toolbar, and then select Show or Hide Document Properties in the Show or Hide toolset.

2. In the pop-up document properties window, select the Security tab. In the Security tab, find the options that prohibit printing and copying, and uncheck them. Find the options that prohibit changes and uncheck them.

3. In the Security tab, find the restricted editing option, select Read Only, and then click OK to save the changes.