Conference camera interlaced and progressive scan difference
May 18, 2018
Conference camera interlaced and progressive scan difference
Interlaced and Progressive are methods for displaying moving images on a display device. Interlaced scanning is a method in which each frame is divided into two frames for alternate display, and progressive scanning is for all frames of each frame. Also displayed. The scanning method of a typical liquid crystal television display screen is from top to bottom from left to right, scanning a fixed number of frames per second.
Interlaced scanning means that each frame is divided into two fields. Each field contains all odd-numbered scan lines or even-numbered scan lines in a frame. Usually, the first field is scanned by scanning odd lines first, and the second field is then scanned by scanning even lines. Due to the persistence of vision, the human eye will see smooth motion instead of flickering half-frame images. However, flicker that is hardly noticeable appears at this time, making the human eye easily fatigued. This flicker is particularly noticeable when the content of the screen is a horizontal stripe.
The progressive scan displays the entire scan frame each time. If the frame rate of the progressive scan is the same as that of the interlaced scan, the human eye will see a smoother image than the interlaced scan, with less flickering than the interlaced scan. The progressive scan method makes the spectrum of the signal and the channel bandwidth for transmitting the signal reach high requirements. The principle of operation is to divide a 625 line image into two fields. The first field is called odd field. It scans only 625 odd lines (scans 1, 3, 5,... Lines in sequence) and the second field (even field). ) Scan only 625 lines of even-numbered lines (sequentially scan lines 2, 4, 6, ...). The number of lines scanned by the original frame is completed by two fields of scanning. This is interlaced scanning. For 625 lines of interlaced scanning per frame, each frame is divided into two field scans. Each field scans 312.5 lines. Only 25 frames are scanned per second. Therefore, a total of 50 fields are scanned per second. 25 fields each for the odd-numbered field and the even-numbered field), that is, the frame frequency is 25 Hz and the field frequency is 50 Hz in the interlace scanning.
