You are using that display terminology differently from everyone else. 2K, 4K, etc. refer to horizontal resolution, and 720p, 1080p, etc. refer to vertical resolution. 0.5K would be something like 512x384, an ancient resolution lower than VGA (I used it sometimes in the 1990s), and definitely not 720p, which is 1280x720. 2K, 4K etc. came from cinema and filmmaking, but 720p, 1080p etc. come from TV and computers; the "p" stands for "progressive scan", contrasting with "i" for "interlaced" (a lot of HD TV broadcasts are 1080i).