Put the image in a TV (template variable), then install this:
[Snippet] Lightbox JS combined with phpThumb then in Ditto templates, use that snippet to do the thumbnail image using a call like [[lightboxImage? &width=`100` &height=`100` &tv_image=`myImageTV`]]
"He can have a lollipop any time he wants to. That's what it means to be a programmer."