The built in image viewer in Firefox is a very basic one and is not that useful at all (or at least in my experience). If you too find that to be true, then you can try ”ImgViewerPlus’. It is an add-on for the Firefox web browser that adds few very useful features to the built in image viewer.
It lets you use both keyboard and the mouse for controlling various functions when viewing an image. And as you can see from the below screenshot, it has a built-in transparent toolbar that you can use to Zoom in/out/reset, Rotate (clockwise/counterclockwise), move the image around plus also lets you change the default background color as well.
If you think the toolbar is a distraction, then you can use the small top icon for hiding it or, you can completely disable it from the settings page too. And because using the mouse to control an image is so easy, I prefer to disable the toolbar completely.
You can use the scroll wheel for Zoom in and out. If you press the left-click, then it will reset the zooming. Once selected an image, if you right-click on and hold, then you can freely move the image around to anywhere too.
However, you no longer can get the default context menu when you right-click on an image (for saving it to disk etc), as from now, that function is used to move the image. I almost panicked once realized it ;-).
But in its settings page, it says that you can still get that context menu by holding down the ‘Shift’ key when right clicking, and it did the trick. Also, I don’t know if it is a feature in Firefox or something that ‘ImgViewerPlus’ adds, but I’m pretty impressed by the zooming quality.
So just to check, I saved an image to disk and zoomed it in Windows 7’s image viewer. Then I opened it in ‘ImgViewerPlus’ and zoomed it to the same level, and I could easily see the one zoomed by this extension is to be of far better quality than the one zoomed in Windows 7!.
Sure, the images look slightly blurred when zoomed (I guess it is an effect to minimize the cluttered looks that appear when zoomed), still, they looked much better.
Anyway, after installing, it does not ask you to restart the web browser either. However, if I remember correctly, the keyboard shortcuts started to work, only after I restarted the browser.
If interested, please visit this ‘ImgViewerPlus’ add-on page for getting it.