Progressive Scan
A method of imaging and transmitting all scan lines sequentially at each frame, as opposed to interlaced scanning, which divides the image into two time-shifted fields.
Explanation
逐行扫描 (Progressive Scan) is a method of displaying a complete picture at each image instant, with scan lines arranged sequentially from top to bottom to form a frame. The `p` in the numerical notation stands for progressive scan, as in 720p, 1080p, and 2160p.
All lines in a progressive frame are sampled at the same time; still and moving areas do not need to be composited between two fields, making it suitable for digital displays, computer graphics, and subsequent scaling. The frame rate determines how many complete frames are displayed per second; 1080p24 and 1080p60 are both progressive, but have different temporal resolutions. Progressive content can be transmitted via an interlaced interface. A Progressive Segmented Frame divides the odd and even lines of the same progressive frame into two segments with no time difference; film pull-down repeats the fields of a progressive source in a specific field order. Media detection that only examines the transmission structure may report such content as interlaced.
Deinterlacing an interlaced source to produce a progressive output does not make the source natively progressive. The algorithm must reconstruct missing scan lines in areas of motion, which may result in combing, jagged edges, or temporal smoothing. Databases should distinguish between the source scan, encoding flags, and player output.