image resize/scale quality

Thanks for making this – by far the fastest and most appealing lightbox I’ve used yet, an example implemented and customized here:

http://www.mccarch.com/seattle_architects/equestrian_architecture/island-equestrian-estate/

I made some small tweaks to adapt to the style of the site.

However like many light boxes, the image resize is fast, but at the expense of a really sharp image. Is there any way to use a different image resizing software, or to pass paramters for a better (even if slower) image scaling algorithm? Thanks again for the great lightbox!

https://wordpress.org/plugins/slenderbox/