: You can only view the highest resolution that the user originally uploaded; if they uploaded a low-quality photo, no viewer can make it true HD. Tips for Better Quality
If you are trying to ensure profile picture looks HD:
Be cautious of tools that require you to log in with your Facebook credentials. These are often scams intended to steal account data. How to View Locked Facebook Profile Picture in Full Size
Many extensions claim to "unlock" HD images. They have names like "Facebook Photo Zoom" or "Profile Picture HD."
The browser will serve the largest available version of that image. It is not always "HD," but it is often 2-3 times larger than the standard pop-up.
If you want to see your profile picture in HD (or save it), follow these legal steps:
Facebook often compresses profile images, making them look pixelated on your screen. If you want to see the original, high-def version, an HD Profile Picture Viewer is the way to go. Why use one? Full Resolution: View photos in their original size. No Login Required: