Re: Ultra-cheap LCD Delivers Fair Performance for Fair Price
- From: Frank Provasek <frank@xxxxxxxxxxxxxx>
- Date: Wed, 6 May 2009 13:56:39 -0700 (PDT)
On May 6, 2:26 am, nos...@xxxxxxxxxxxxxxxxx (Alan) wrote:
In article <3a3677b4-0d57-43c1-b640-cb02712bf...@xxxxxxxxxxxxxxxxxxxxxxxxxxx> Frank Provasek <fr...@xxxxxxxxxxxxxx> writes:
I saw this set (TX-42F450S) in person at Costco. Picture quality is
good, but the 1000:1 contrast ratio indicates that it does not have
a dynamic backlight. Some of the new Samsung models have 1,000,000:1
contrast by using LED backlights.
The dynamic contrast is a bogus number, because if you really care about
contrast, you will want it to apply between any pair of pixels. If they are
lit by the same backlight, and the backlight is varying its brightness to
enhance the contrast range, then the dark pixel will have varying amount of
leakage when the backlight turns up to brighten up the bright spot (or the
bright area will be pulled down when the backlight dims for dark pixels).
You obviously don't understand how LED backlights work. Brightness of
small areas
of the picture are separately adjusted.
Nonsense: why do you think a TV screen is generally unviewable
Either way, you lose. Visually, it can be very annoying, and once you
notice it, you will be looking for a way to turn it off.
The human visual system reportedly has a contrast range of about 250:1,
so the 1000:1 is more than enough.
outdoors?
The Dynamic Range of the Eye
The Human eye is able to function in bright sunlight and view faint
starlight, a range of more than 10 million to one. But this is like
saying a camera can function over a similar range by adjusting the ISO
speed, aperture and exposure time.
In any one view, the eye eye can see over a 10,000 range in contrast
detection, but it depends on the scene brightness, with the range
decreasing with lower contrast targets. The eye is a contrast
detector, not an absolute detector like the sensor in a digital
camera, thus the distinction. (See Figure 2.6 in Clark, 1990;
Blackwell, 1946, and references therein). The range of the human eye
is greater than any film or consumer digital camera.
Here is a simple experiment you can do. Go out with a star chart on a
clear night with a full moon. Wait a few minutes for your eyes to
adjust. Now find the faintest stars you can detect when the you can
see the full moon in your field of view. Try and limit the moon and
stars to within about 45 degrees of straight up (the zenith). If you
have clear skies away from city lights, you will probably be able to
see magnitude 3 stars. The full moon has a stellar magnitude of -12.5.
If you can see magnitude 2.5 stars, the magnitude range you are seeing
is 15. Every 5 magnitudes is a factor of 100, so 15 is 100 * 100 * 100
= 1,000,000. Thus, the dynamic range in this relatively low light
condition is about 1 million to one, perhaps higher!
.
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- Re: Ultra-cheap LCD Delivers Fair Performance for Fair Price
- From: Frank Provasek
- Re: Ultra-cheap LCD Delivers Fair Performance for Fair Price
- From: Alan
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