As you know, iMessage overcomes many of the limitations of standard MMS. Every time you attach an image taken on your iPhone and iPad to an iMessage, it's delivered in its original size and resolution. Some downscaling may occur, but only for very high resolution images: those taken with an iOS device are always delivered in their original form without any resizing taking place.
And herein lies a problem for those of you who send a lot of images via a cellular data connection.
Knowing a typical photo taken on an iPhone 6s weighs in at between three to five megabytes (or even more), it does add up pretty quickly. If you're concerned about cellular data consumption (as you should be), pay attention as Messages on iOS 10 offers a brand new low quality mode.
We've determined it downscales images sent through iMessage to circa 100 kilobytes each. In other words, for the amount of data you'd normally spend to shoot someone a single photo via iMessage you get to send 30 to 50 images in low quality mode.