Best way to compress non power of 2 image

Hi there, by some reasons I have a lot of images (histories) that I need to show on device, the images are jpeg 768x1024, the images are normally 40 to 120Kb. But when I use them on unity it shows 0.8 MiB or even 2.2 MiB instead of only some Kb.



Also I would love to see the final package size of the things because the app size is going up (I think the major part are this images), but would love to know really where the space is going (I think the code are about less than 5Mb compiled).