Q: File size and format of photos in a shared album?

I'm taking high-resolution photos in .tiff format on my iPhone with iOS 8.4.1. They turn up in the Photostream album on my iPad mini, currently iOS 7.1, soon to be 8.4.1.

I understand that a photo included in the Photostream album appears as a .jpg at a lower resolution compared to the original .tiff taken on the iPhone.

From https://support.apple.com/en-us/HT201317

What resolution are My Photo Stream photos?

On iPhone, iPad, iPod touch, and Apple TV, your photos are delivered in a device-optimized resolution that speeds downloads and saves storage space.

If I access the photo through an iCloud shared album, though, is that photo at its original high resolution in its original file format? Here's what I've found so far:

From http://help.apple.com/icloud/#/mmc0cd7e99

Note: Shared albums are called shared streams on iOS 7 devices.

From http://www.ilounge.com/index.php/articles/comments/icloud-photo-stream-and-image -quality/

Shared Photo Streams in iOS 6: Photos uploaded to Shared Photo Streams are always resized [i.e. downscaled] to the maximum 3.1-3.5 MP resolutions noted above, and will therefore be in those lower resolutions even in Aperture, iPhoto or the Windows iCloud Control Panel. As the name implies the Shared Photo Streams feature is designed for sharing photos, and not intended as a means to transfer full-resolution photos back to your computer.

Again, my question is: If I use my iPad mini to access a .tiff photo taken on my iPhone through an iCloud shared album, is that photo at its original high resolution in its original .tiff file format? Or is it a lower resolution .jpg file?