interlaced displays

torabisu · 04-18-2006, 06:29 PM

I'm familiar with the structure and format of interlaced and progressive video signals but what does it mean to have a 1080i display? If LCDs, plasmas, etc are all inherantly progressive, whats the basis for the 'i' in a 1080i display?

Does this just refer to the ability of the display to render a full 1080i signal? :

If so, why bother with the 'i'. All ATSC TVs to spec must deinterlace such a signal to be displayed progressively so 'i' is implied. Is it's meaning perhaps "only accepts 1080i not 1080p"? However, as far as I know, there are 1080i displays that accept 1080p signals.

Does it refer to how the source video is interpreted? :

Will a 1080i tv interlace a progressive signal (eg. 720p or 1080p) and then promptly deinterlaced it to be shown progressively (ie. extracting a field from each frame and then interlacing the fields)? Or will these displays recognize a progressive signal and show each frame in full?

Kind of trivial, but let me know what you think.

InitialDMP5 · 04-18-2006, 08:06 PM

I thought a 1080i television also could understand 720p, so if the channel or source is in 720p, the television would "switch" to that signal. I'm probably horribly wrong, but I would now like to know.

torabisu · 04-18-2006, 09:57 PM

Yeah, thats one of the questions I posed above. A 1080i DTV to spec must accept 720p but how does it display it? Does it show each frame progressively or does it interlace the signal and show the deinterlaced frame?

BobY · 04-18-2006, 10:21 PM

The only interlaced displays are CRT, which display a 1080i signal as interlaced because they don't have the bandwidth to display it progressive. AFAIK, none of them even have the bandwidth to display 720p. They either take a 720p signal, upscale it to 1080p, then interlace it to 1080i for display (throwing away every other frame) or, more likely, downscale 720p to 540p, then line-double or upscale to 1080i.

04-18-2006, 06:29 PM	#1
torabisu What is HD? Join Date: Apr 2006 Posts: 2	interlaced displays I'm familiar with the structure and format of interlaced and progressive video signals but what does it mean to have a 1080i display? If LCDs, plasmas, etc are all inherantly progressive, whats the basis for the 'i' in a 1080i display? Does this just refer to the ability of the display to render a full 1080i signal? : If so, why bother with the 'i'. All ATSC TVs to spec must deinterlace such a signal to be displayed progressively so 'i' is implied. Is it's meaning perhaps "only accepts 1080i not 1080p"? However, as far as I know, there are 1080i displays that accept 1080p signals. Does it refer to how the source video is interpreted? : Will a 1080i tv interlace a progressive signal (eg. 720p or 1080p) and then promptly deinterlaced it to be shown progressively (ie. extracting a field from each frame and then interlacing the fields)? Or will these displays recognize a progressive signal and show each frame in full? Kind of trivial, but let me know what you think.

04-18-2006, 09:57 PM	#3
torabisu What is HD? Join Date: Apr 2006 Posts: 2	the "i" in "1080i display" Yeah, thats one of the questions I posed above. A 1080i DTV to spec must accept 720p but how does it display it? Does it show each frame progressively or does it interlace the signal and show the deinterlaced frame? Last edited by torabisu; 04-18-2006 at 10:05 PM.

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04-18-2006, 08:06 PM	#2
InitialDMP5 High Definition is the definition of life. Join Date: Jan 2005 Location: San Francisco Age: 28 Posts: 336	I thought a 1080i television also could understand 720p, so if the channel or source is in 720p, the television would "switch" to that signal. I'm probably horribly wrong, but I would now like to know.

04-18-2006, 10:21 PM	#4
BobY What's all this, then?... Join Date: Jan 2006 Posts: 6,197	The only interlaced displays are CRT, which display a 1080i signal as interlaced because they don't have the bandwidth to display it progressive. AFAIK, none of them even have the bandwidth to display 720p. They either take a 720p signal, upscale it to 1080p, then interlace it to 1080i for display (throwing away every other frame) or, more likely, downscale 720p to 540p, then line-double or upscale to 1080i.