[Tig] Sony PVM-1741 / PVM-2541 contrast ratio?

Jim Houston jdhouston at earthlink.net
Wed Sep 12 15:35:23 BST 2012


On Aug 21, 2012, at 3:08 PM, Juan Salvo wrote:
> 
> It's technically infinite as the OLED panels do not emit any light
> when inactive. I think Sony marketing is referring to it as
> 1,000,000:1 in their marketing.

Measuring an actual on/off state, I got a number around 12,000:1
with a small amount of ambient light in the room. 

Because sequential contrast used to correlate to the quality 
 of the image contrast and was easy to measure, it was 
convenient to spec monitors on the full white to full black range
in a fully darkened room.   This is a better situation than almost
 any user would normally have, so the number was optimistic.
So now, there is a device that at full black is just turned off in
 a darkened room,  you can pick whatever number you want
 at that point mathematically, but it isn't a number that will make 
 sense. So for example,  a million to one claimed contrast would
 put the black at a measured value of  0.00003 fL  or  0.0001 nits.
(for reference, the black duvateen in a darkened movie theater
measures at around 0.0008 fL.)  If you turn on even a few pixels
 with actual light, the average black due to flare in the glass
 will rise substantially.

The measure that really counts is the simultaneous contrast 
from measuring a checker board and averaging results.
This number is surprisingly low, (about 250:1 for LCD's), but is a better
 indicator of the quality of contrast in normal images.  I don't 
 have that number for OLEDs at the moment.

Overall, the OLED has great looking blacks because of lack
 of flare.   A CRT could be measured up to 25000:1 contrast
 but did not look as good because of flare from the image.

Jim Houston
Pasadena, CA



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