Show image when in viewpoint of browser window
Correctness


You need to handle resize events also. Yes, you can add it like : $(window).on('scroll load resize', ...
You are only checking for the visibility of the top/left corner, if you load a large image, scroll right, and then scroll down, you will see the right edges of the ALT text of the images, but because their top/left corner is not in viewport, those images will not load. You might want to check if any point of the img box is visible.


Browser Behavior


Make sure you have &lt;!DOCTYPE HTML&gt; on your document, this will load all images if you miss doctype declaration. (for Firefox, Chrome, don't know about others)
You might want to mark images processed, by adding a class or another data; and do not fiddle with the src attributes of the images once they are loaded.


Javascript related


Because you miss a var before $eleImage and elementOffset, they pollute global namespace.
You copy the value of $(this) here : $eleImage = $(this), but you keep using $(this) below.