LazyLoad Playeholder image with dimensions of original image?!

Thanks for this great LazyLoad plugin it′s very nice!
I have one quetsion. I ist possible to load the placeholder with the original image demensions?
I use Salient WordPress Theme and this theme uses isotope to construct page elements on load.
So if the image size changes after lazyload resize the content and image get in conflict like covering each other and such things.
Can you help me?
Best Regards!