Bizarre Quark 5.0 and JPEG phenomenon

I have a Quark 5.0 document that contains a lot of JPEG images. If I increase the size of the JPEGS, from less than 96k to more than 96k, it actually results in a considerably smaller Quark file. How could this be? The only thing I can figure out is that some kind of automatic compression occurs above 96k that greatly reduces the file size. Or is there another reason?

One possibility is that JPEGs under a certain size are included within the Quark file, while JPEGs over that size are instead stored separately and the Quark file contains a reference to the images, which are loaded when necessary. There is probably a setting in Quark to adjust that kind of thing.