[Source: How-to-Geek]

Firefox resizes large images by default to fit in the browser window. This can get really annoying if you are browsing a lot of large images.

To see this in action, you can click the link to the really nice Ubuntu wallpaper. You’ll notice that you have to click on the image to show the full size version.

1280×1024 Ubuntu Wallpaper

To change this setting, follow these steps:

• Type about:config into the address bar in firefox.
• Type in browser.enable in the Filter bar and hit enter
• When you see “browser.enable_automatic_image_resizing”, double click it and the value should change to false, as shown.