Rin Stowleigh <
rstow...@gmail.com> wrote:
>It seemed like an easy-enough task, I've read good things about at
>least one 120hz LCD monitor with regard to overcoming the things I
>hate about 60hz LCD gaming, so I figured I would pick up about a 32"
>120hz 1080p set.
There's a world of difference between a 120 HZ computer monitor and 120
HZ TV. The first takes a 120 HZ signal from a computer and displays it
at 120 HZ, the second takes 60 HZ signal and converts to 120 HZ through
frame interpolation and displays that. A 120 HZ TV won't accept a 120
HZ input and won't gain any of the benefits of a 120 HZ monitor.
If you're looking to buy an LCD TV and use it primarily as a computer
monitor then I would suggest looking for one that supports 1:1 pixel
mappping, 4:4:4 chroma, has low input lag, and a low response time. Some
of these features are easier to find than others.
Just about any TV should support 1:1 pixel mapping, but not by
default. Even when fed an image at their native resolution, they crop
out the edges and then scale it up to fit. This is because broadcast
TV and other sources often have junk appearing the top of the screen
(and some times the other edges) that can be distracting. Componding
this problem is the fact that video cards will will add a black border
(overscan) to the output when it thinks its connected to a TV so that
this border gets cropped instead of the Windows desktop. You'll need
to both the disable the cropping on the TV and disable the overscan in
the video card to get a 1:1 pixel mapping.
Support for 4:4:4 chroma is much harder to find. The general problem
here is that HDMI and TVs use a 4:2:2 YCrCb pixel format by default.
With this pixel format, raw three component RGB data is converted into
one greyscale and two colour difference components. The greyscale data
is transmitted at full resolution, but the colour difference channels are
transmitted at half the horizontal resolution. For most uses halving the
colour resolution like thisisn't noticable, but it can make a computer's
text look blurry.
Not that many TVs support 4:4:4 chroma, even if fed a full chroma
resolution RGB 4:4:4 format signal they will still convert it into 4:2:2
YCrCb in order to do their internal processing. Video cards will also
by default transmit 4:2:2 YCrCb if they think they're connected to a TV.
With ATI cards that can be fixed in the control panel, but with NVIDIA
cards apparently you may need to use a fake EDID force it to use a RGB
4:4:4 pixel format when connected to a TV. In some cases using a DVI
to HDMI cable can fool the video card and/or TV.
Input lag can be a small and unnoticable, or game breaking depending
on how bad it is and what sort of games your playing. In the worst
case it can even make moving the mouse around the Windows desktop feel
unresponsive. The cause of input lag is processing done by the TV.
LCD computer monitors do very limited processing, practically none at all.
There's typically one frame (1/60th of second) or less delay between
the time the electronics in a computer monitor receive image data at
one of their inputs and it gets sent to the LCD panel for display.
LCD TVs all unfortunately process thier inputs in some way, and this
causes an additional delay.
The LCD TVs with the lowest input lag are almost invariably the cheapest
TVs that support the least amount of processing. A 120 HZ TV is terrible
choice in this regard because 60 HZ to 120 HZ interpolation requires
buffering multiple frames which increases the input lag signifcantly.
While this interpolation can usually be disabled, either explicitly or
through a "Game" mode which disables many of the TVs processing features.
Most TVs have a "Game" mode like this, but even when using this mode
the more expensive more feature rich TVs still tend not to score as well
their cheaper more barebones cousins.
Response time of LCD panels isn't a big deal as it used to be, but with
TVs the problem is generally worse. There's so much bogus information
from manufactures about the resonse time of their LCD monitors and TVs
that it's hard to really compare them. Most people these days don't
seem to notice LCD motion bluring caused by the amount time it takes an
individual liquid crystal element to switch from one state to another.
I wouldn't have bothered mentioning it but the response time on CRT
monitors and plasma displays is zero, so this could be an issue for you.
Almost all LCD montitors use TN panels, which aside from being cheap have
only one advantage over the other kinds of TFT LCD panels. They have
low response times, and so less motion bluring. Only small crappy
TVs use TN panels, the poor viewing angles of TN panels make them
generally unsuitable for a display that could have multiple viewers
sitting around it. While some TVs claim to have low response times,
typically they're going to be higher than a TN LCD monitor.
I bought an LG 42LK450 for use both as a TV and a second monitor for
my PC. It supports 1:1 pixel mapping, 4:4:4 chroma and has very low
input lag for a TV. The pixel response time isn't so great, but I've
still got my CRT as my primary monitor. I was originally thinking of
getting the 32" 32LK450 instead of the 42" model, but I ended up getting
the 42" for the same price the 32" sold for when it was still in stock.
I just put the the TV further back than I had originally planed.
Ross Ridge
--
l/ // Ross Ridge -- The Great HTMU
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rri...@csclub.uwaterloo.ca
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