For some reason the Showcase slideshow is reducing my 888px images to thumbnails. I have set the module options as follows:
Show Title - No
Enabled - Yes
Module Position - showcase
Slideshow Width - 888
Slideshow Height - 162
and all of my full size images are being displayed on the site as thumbmails.
... You'd have plenty of company in that pile of snow.. it's a mistake I've often made myself.