How can I prevent Unity from inflating the size of my images?

Hello, I have five jpg images that I added to my Unity project, all of them under 500K in size before I added them. After adding them to to Unity, the Inspector showed each of them to be 4.1 MB! My guess is that Unity is uncompessing the files and then using their own compression, as I have those assets type set to compressed. Making them 16-bits instead of compressed drops the size to 2.7 from 4.1 MB - still too big. Is there a way to keep this image files small? Otherwise, I'll have to resort to mixing the text and smaller images, which is a pain and won't look as good.

Thanks so much for all your wisdom!