Does Progressive still scan from top to bottom?

I don't get what you're asking. That's how televisions work, line by line. They always have. That's why filming screens often results in a bar moving vertically if it's not synced right.
 
Its been a little while since I really thought about it and I might be wrong BUT....progressive scans every line on the tv in order. Interlaced scans a line then skips a line then scans a line etc. then goes back to the top of the screen then hits the lines it skipped the first time thus alternating. I hope my old Broadcast professors arn't looking at this forum just in case Im wrong haha!
 
That is correct.

Interlaced scans every other line first, then the missing ones. Progressive scans all at once.

How the actual image is scanned/exposed depends on the sensor. "Global Shutter" systems - like most all CCD cameras expose the whole frame at once in progressive mode and then read off the data line by line. (In interlaced mode, they expose half, then the other half). "Rolling Shutter" systems - most CMOS sensor cameras on the market actually scan line by line down through the frame over time; resulting in Skew, Wobble, etc..

- Mikko
 
There's a difference between how a CCD "scans" its image, and how a progressive-scan display draws that image.

The CCD (or global-shutter CMOS) "sees" the entire image simultaneously. There is no scanning at all, it's all immediately exposed.

The progressive-scan CRT monitor "draws" each line progressively (from top to bottom). This is unlike an interlaced monitor, which draws each odd line progressively, then each even line progressively).

In that way, the progressive-scan CRT monitor and the rolling-shutter CMOS sensor work more similarly to each other; the rolling shutter scans each line progressively down the frame, and the progressive-scan CRT draws each line progressively down the screen.

But global-shutter and CCD progressive-scan don't work that way, they expose the entire frame simultaneously. There is no scanning at that point, it's global exposure.
 
"The progressive-scan CRT monitor "draws" each line progressively"

which is to say a LCD monitor also draws each line? Hey, I might be learning something here! :)
 
You must log in or register to reply here.
Back
Top