Standard 720p scaling filters (such as Bilinear or Bicubic) expand the video size without trying to "invent" new pixels. This retains the soft, nostalgic aesthetic of early A-1 Pictures and Satelight production values .
In the early 2010s, broadcast anime and direct-to-video OVAs were rarely mastered in Full HD. Most studios worked in 720p to save render time and bandwidth on physical media (Blu-rays were still adopting 1080p encoding). When you find a "1080p" version of Fairy Tail OVA 1: Welcome to Fairy Hills , it is almost certainly a software-upscale. Fairy Tail Ova 720p Or 1080p
If the file name says "WEB-DL" (web download), be cautious—streaming services sometimes compress OVAs harder than physical Blu-ray encodes. Standard 720p scaling filters (such as Bilinear or