I wanted a plug-in to open a lightbox (or similar) to display original image, on clicking image thumbnail in front-end article.
SP Thumbnail was very simple to install and use, and the facility to use CSS class(es) to control lightbox is exactly what I need. Well done! Modal window opens very fast.
However, it does not seem to generate a thumbnail for the small view - but uses the original image, scaled by attributes of img element - no saving in page display times etc for large original images.
So a miss for me I am afraid.