This would solve a problem that can happen, especially if the images already have a transition effect applied. With animation the style is applied in a specific time frame without interfering with the css style. 

it's a small modification I know, but it can make everything more beautiful (or less glitchy). Thanks for your script it's very useful to me!

small changes to meet the standard and a fix
- missing opacity: 1 on the background while the image is loading 
- replaced spaces with tabs 
- restored the original value of .3s for the animation (personally I prefer .1s though)

this way there is even less chance of flickering for images to which opacity has been applied