The differences between INTERLACING &PROGRESSIVE?

Answer 1

Simply, in a conventional CRT TV, the picture consists of 525 horizontal lines and displays or scans half the lines at a time, odd lines first. The other half, the even lines are filled in or interlaced during the next scan cycle.

Progressive displays the picture or lines all at one time.

Answer 2

interlaced video is comprised of two partial video fields of alternate lines. In laymans terms this means that each video frame is actually made up of two partial frames. In interlaced video these two frames are recorded one phase cycle apart (think voltage frequency) so half the frame is recorded then the other half is recorded 1/50th or 1/60th of a second later depending on the supply voltage where you live. This was devised for a few reasons: To save bandwith in analogue broadcasting, and to enhance the perception of smooth motion. You have two methods of deinterlacing. One is to merge the two fields so that they are both displayed at once. Fine except on moving subjects where that 1/50th or 1/60th delay comes in and you get combing on the edges because the subject has moved between the two half frames. The other is to disregard one field (or half frame) and just show one of them and let the computer guess either guess what should be in the missing area, or just repeat the picture lines to fill the gaps. One method can throw up mistakes, the other saps the resolution back to effectively SD quality. Some camcorders do have a progressive mode, either by changing the sensor read off, or by doing some image processing tweaks in camera. Progressive video will play back fine on anything, interlaced can be troublesome on computer monitors or in use on youtube etc. The best camera is the one you've got to use just now. I wouldn't get too hung up on the engineering. Selectively deinterlace where problems occur.

Answer 3

Look at a standard def TV. Notice the scan lines going horizontally? This is due to the interlace technique of drawing odd rows, then even rows.

Look at your computer monitor. Notice the scan lines? No - This is because the entire screen is painted in 1 pass or in a "progressive" fashion.

Is this the type of difference you wanted?

Answer 4

Lets use 1080i and 1080p for an example. for 1080p the TV will update the whole screen (all 1080 lines) at once every 1/30th of a second. For 1080i the TV will update every other lines once every 1/60th of a second. Both end up with 30 frames per second. The real difference is what happens between the frames. 1080i shows a mixture of two frames, each line alternating between them. See http://www.geniusdv.com/weblog/archives/Interlcaed.jpg for an example.