Just determining whether or not the user can see an image is quite tricky when you consider that there are a number of things which could cause it to be invisib

Just determining whether or not the user can see an image is quite tricky when you consider that there are a number of things which could cause it to be invisible to the user and thus safe to remove: * It might be placed as a normal block element on the page but out of the current viewport. * It might have had visibility: hidden CSS statement applied to it. * It might have had display: none CSS statement applied to it. * It might have the alpha channel set to fully transparent and then fade in. * It might be inside a <div> that has overflow: scroll and then have that specific div scrolled such that the image is outside the viewport of that <div> * It might be using top and left CSS properties to animate the position of the element such that it is off the screen. * It might have it's CSS width or height set to 0 so that it can be start out "hidden" and then have animate open. So I wouldn't discount this as just a simple solution because I see a lot of edge cases where things could get confusing just due to the complexity of how many ways there are for a page element to be visible versus not visible.