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Discussion Starter · #1 ·
I'm new to considering projectors at all, having just come over from direct-view CRTs. Over there, a big factor is whether or not a given HDTV or monitor supports various resolutions "natively". For example, practically all HDTV sets can't scan their electron guns across the screen more than 540 times per frame, so 720p support comes in the form of conversion to 1080i, instead of literally showing 720p with the gun scanning the screen 720 times. One reason I was looking into the Monivision CRT monitors is that they have true native support for a bunch of different resolutions, no converting necessary. This "multi-scan" ability is an advantage of monitors over TVs, even HDTVs, in the CRT universe.


But how does it work when you're dealing with a screen with a set number of pixels? 1:1 pixel mapping is apparently thought of as an advantage around here, but I can't imagine how it can work without original signals being converted to the screen's resolution if they don't already match it, since you don't have a "gun" scanning across the screen and it wouldn't do to hit fractions of pixels.


So, conversion is a good thing in the fixed-pixel world, even though it's said to degrade quality in the CRT world? And it's simply directly because of the physical traits of the things making the images? Or do I misunderstand the meanings of some terms here, such as that fixed pixels aren't really as fixed as they sound or something... and in that case, what is 1:1 pixel mapping, and does it conflict with "native" resolution display or not?
 

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Delvo,


The advantages of 1:1 pixel mapping on a fixed pixel display are typically realized when a HTPC is used. Since PC's have traditionally been better scalers and deinterlacers than most of the dedicated solutions out there, the best image could be generated by taking a source (DVD for instance) and scaling it to the native resolution of the projector, then passing that signal on (preferably through digital means like DVI) to the PJ. The PJ gets a pixel perfect 100% digital image, scaled and deinterlaced by one of the most effective means available (PC).


Another benefit is if you're actually trying to use the projector as a display for your computer for playing games or surfing the web, etc.. You want a pixel perfect signal from the PC, otherwise the projector will squash or stretch the image in ways that will degrade it. Effectively, the image will lose its crispness, and text and other images will become distorted.


All that being said, in today's World, where excellent scalers/deinterlacers can be had in even the least expensive projectors, the need for 1:1 pixel mapping is less critical for DVD viewing. The primary concern now is getting that all digital signal to the projector (via DVI or HDMI). If you have that, and your PJ has good scaling (Faroudja, Pixelworks, etc..), you'll get an excellent image. However, if you still want to use your projector for web surfing or other PC applications, 1:1 pixel mapping is still pretty important.


--Scott
 

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Discussion Starter · #3 ·
Quote:
Originally posted by scottpe
The advantages of 1:1 pixel mapping on a fixed pixel display are typically realized when a HTPC is used.
Spiffy. HTPC is what I had in mind. (I came to the projector forum after discovering that the Monivision CRT I'd been planning on was a few hundred dollars more expensive than I thought, and that projectors can apparently be bought cheaper than I'd thought. I know some are still multiple times the price of the lowest-priced; what's the difference that customers would be paying for?)

Quote:
Originally posted by scottpe
The primary concern now is getting that all digital signal to the projector (via DVI or HDMI).
I figured that would be the case with screens that are physically digital (LCD, DLP), instead of controlled by an analog physical entity like the CRT electromagnet. But it's surprizing that, with direct-view LCD panels taking over from CRTs in the computer monitor market, there isn't yet more of a standard for connecting computers to digital displays by digital means, without the D-A-D conversions that using the CRT-era VGA connections imposes. The computer world seems to have to borrow connections from the TV world, since DVI is from there and this "HDMI" sounds like it is too, if "HD" refers to HDTV. I'd never heard of HDMI before this; where can I read about the differences?
 

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Quote:
Originally posted by Delvo
But it's surprizing that, with direct-view LCD panels taking over from CRTs in the computer monitor market, there isn't yet more of a standard for connecting computers to digital displays by digital means, without the D-A-D conversions that using the CRT-era VGA connections imposes. The computer world seems to have to borrow connections from the TV world, since DVI is from there and this "HDMI" sounds like it is too, if "HD" refers to HDTV. I'd never heard of HDMI before this; where can I read about the differences?
Delvo,


There is a standard for connecting computers to digital displays.... it's DVI! Most of the decent video cards from Nvidia and ATI come with DVI connectors built in -- No D-A-D conversion needed.


HDMI = High-Definition Multimedia Interface


It's basically the next evolutionary step beyond DVI, and is starting to arrive in some of the brand new projectors (e.g., Sony's HS20). You can learn all you want to know from HERE


Take care,


--Scott
 
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