Q: I’m a bit confused about Apple’s Photo Stream feature. I’ve been told that it actually doesn’t store my full-resolution pictures, so I’m kind of wondering what the point is. I can sort of understand that if it’s only about sharing pictures between by devices, but why would I want to use it on my computer if it’s downscaling and modifying my images. Also, what about things like GPS and time information stored in my photos? Is that preserved or stripped out? I know that I used to lose this information when e-mailing or uploading photos to MobileMe. Does Photo Stream do the same? Thanks for any help you can give me.
A: The standard iCloud Photo Stream feature uploads your original photos as-is, in their original resolution with all metadata intact. This means that your photos as transferred to your Mac or Windows PC will be the original photos from your device.
However, where this gets confusing is that iOS stores a downscaled version of your photo in the Photo Stream section on your devices. This is true even on the device where the photo originated. The specific resolution of the Photo Stream stored photos varies slightly between devices as it is optimized for the screen resolution, but the maximum is between 3.1 and 3.5 megapixels, depending on the photo’s aspect ratio—2048 x 1536 for standard 4:3 images, a slightly higher 2304 x 1536 for “pro” camera 3:2 images.
This basically means that even on the iPhone 4 the images stored in your Camera Roll will be significantly higher in resolution than those stored in the Photo Stream. If you’re planning to work with original, full-resolution images in another app on your iOS device you should keep the photos in your Camera Roll even after they’ve been uploaded to your Photo Stream so that you can use these instead of pulling them from the Photo Stream. However, the resolution of photos stored within the Photo Stream should be more than adequate for viewing on the device or uploading to most social networks—many of which will resize the photos to even lower resolutions anyway.
Despite this downscaling, however, EXIF metadata is preserved in the Photo Stream even on your other devices. This means that GPS location information, lens and exposure settings and a proper date and time stamp will be available for those photos.
Keep in mind that this only applies to the main Photo Stream feature, not to the new Shared Photo Streams in iOS 6. Photos uploaded to Shared Photo Streams are always resized 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.
That said, it’s worth noting that Shared Photo Streams do work fully over either a Wi-Fi or 3G connection, while the standard Photo Stream remains limited to Wi-Fi only, probably at least partially due to the higher bandwidth required to upload full-resolution photos.