@riverbend-comics
Photos are stored on almost all camera devices in landscape orientation (on iPhone and iPad, the dimple would be on the right). On mobile devices and newer cameras, a flag is set in the photo to indicate which side of the camera was down when the photo was taken.
That flag is read by various photo management tools and by newer browsers, and those tools will display the photo as intended by the flag. In some photo management tools, you can rotate the photo, but all it does is change the flag. Other tools may physically rotate the picture, moving all the pixels to a new position.
When you upload to eBay, eBay does not read the flag (eBay does not understand autorotate and strips all EXIF data), so if the pixels were never physically rotated, you might see a sideways picture after it arrives on eBay.
The solution, now that you know you have this problem, is to rotate the photo in an image editor prior to uploading to eBay. In some mobile devices, you can edit the photo and simply rotate all the way around to the correct orientation and the device will rotate all the pixels around. Similarly, you can use the rotation tool on eBay's uploader to rotate the photo all the way around until you come back to the correct orientation. That should change the pixels, not the flag, and the corrected photo will be uploaded to eBay.
Info above is courtesy of Shipscript.
eBay is continually updating this site. Some advice given may have changed. Please reply to this thread, to let us know if this advice works for you. The links on the bottom of any eBay page can help you deal with most eBay issues. Contact eBay Customer Service on Facebook.com/eBay or Twitter.com/AskeBay
