If you want to merge photos side by side, just tap rotate icon to landscape mode. You can see the merged result at a glance with preview function. Press and hold the photo to edit. When you save, you can adjust merged size. Merged photo will be saved in your photo library and you can also share with Email, Twitter, Facebook. A merged result image may be resized when you share by Email, Twitter or Facebook. When you save in your photo library, it'll be saved in a size you set.