What is the best video and movie quality? Part 2
What is the difference between 1080i and 1080p?
Each of these video formats uses a different way to convert a series of still images into movies. In interlaced scanning (“i” symbol), a still image or “frame” is reproduced by scanning 2 sets of alternating lines or “fields” (half frames). With progressive scan (“p” symbol), a frame is created in a single pass (sweep). That is, if the image scanning in both video formats (“i” and “p”) is performed at the same speed, then an equal number of runs per second occurs, then the advantage of progressive scan (“p”) becomes obvious (image quality is better) as the entire image (frame) is scanned and not half of the image (field). This progressive (“p”) scan generates fewer dots and lines, but doubles the speed.
Bottom line: 1080i and 1080p video formats look best in different conditions. The 1080i video format is designed to reproduce fine image details with little movement or in frames and still images. This video format is much better suited for “spatial resolution”. The 1080i video format works fine as long as there is no frame movement. When objects begin to move, the path of movement between alternating fields (half frames) begins to change. This is called “motion artifacts,” that is, visible image noise or video distortion that resembles an uneven pattern. 1080i video quality is considered outdated.
1080p video quality takes priority in motion. It does not introduce visible distortions in the image, regardless of the speed of moving objects, so it has the best “temporal resolution”. However, still images will not look very clear when the image is frozen, because there are far fewer dots and lines in 1080p video compared to 1080i.
Long-distance transmission of HDTV video signal (satellite TV – S2, cable TV) is generally done using compression methods to reduce bandwidth requirements for data transmission (from 1.485 Gbps to 8-25 Mbps ), while the video quality is still good.
