|Sorry I answer came late....
A few months ago I dowload this technical advise writen by a member of TN to another member exposing how the large version works......
Well first here are the limits:
Maximum Size: 400 kilobytes
Maximum Length: 4000 pixels
Minimum Length: 250 pixels
-Overall five megabyte large photo limit. (to my image TL shows no more than 404.800 bytes, nothing about JPEG)
-Posts limited to panoramic images. (Greater than 2.5 ratio)
First you must make your panorama (edit and maybe stitch), then make sure it's within the limits above. Save it and put LP (for Large Post) in the file name so you can distinguish it from the smaller version. Then resize it to be within the limits of normal posts: 800 pixels and 200kb and save that and put SP in the file name (Small Post) this just makes it easier when uploading the photos.
Then upload the small version to the site, then go to your account. Next click on manage (next to upload). Then to the right of your photo, there are a few options:
Large Post (this option will only appear if your photo is greater than 2.5 ratio)
Click on "Large Post" and then upload the LP version.
I hope this helps!
Sunrise over Rangitoto (10)