Optimized image size not showing on front end

The following images were optimized, down to 2500 pixels wide. See these two screen shots: http://take.ms/Xj97N and http://take.ms/edRfD

But I don't see the change in size reflected on the page. The URL for these images: http://mavendesignstudio-demo.com/antique-swan/furniture/art-deco-planter-from-scotland

See this screen shot: http://take.ms/EKZeE

I expected the images to have a width of 2500. What am I missing? I've cleared Joomla cache and browser cache. Not sure what else to check.