[Tig] what are we going to do (monitors)

Bob Kertesz bob at bluescreen.com
Sat Mar 29 21:26:55 GMT 2008

>> If the room was made COMPLETELY dark, the CRT clearly had deeper blacks than
>> the LCD.
>> But if a SINGLE light was turned on anywhere in the room (it was a largish
>> conference room with room for about 100 people), and the light was just bright
>> enough so you could recognize people's faces, the glass front of the CRT
>> picked it up and raised the CRT blacks, and then the LCD had (significantly)
>> deeper blacks than the CRT. This was the case even if the light was behind the
>> monitors - the glass CRT gathered the light from the room and up went the
>> blacks.
>Are you sure that the glass CRT "gathered the light from the room" or 
>is that just what Sony told you?  If the light was behind the CRT, how 
>did the CRT manage to gather the light?

Well, even with the light behind the setup, there was a certain amount of
light bouncing around the room, and the room ambient level was up compared to
no light on at all. The Sony guy said it was the nature of the curved glass
surface on all BVM CRTs to have an inherent bias-like effect on the displayed
image, causing the black levels to rise in some proportional way to the amount
of ambient illumination. I've certainly seen that effect myself over the
years, just hadn't given it much thought beyond setting monitor brightness
looking at actual black (not bars pluge) and seeing that change as ambient
levels changed.

And certainly, in a strictly empirical sense, what he said was happening was
what I (and everyone else in the room) was seeing.

>This is heretofore to be known as the Kertesz effect.

Well, I was hoping to be immortalized due to a somewhat more meaningful event,
but I'll take what I can get.

>The human eye is "biased" by the ambient light level.  Our retinas 
>close down when there is more light, causing our eyes to be less 
>sensitive to it.  There are other adjustments as well.  Perhaps the 
>Kertesz effect is best explained by the behavior of the human eye than 
>the behavior of CRT phosphors when (quite) weakly excited by stray 

I suppose that's possible. But even if that were the case, the incident still
speaks to how we normally set up and view monitors. And since no one I know
does critical viewing or grading with no ambient light at all, the BVM Sony
LCD appeared to have deeper blacks than the BVM CRT under identical ("normal")
viewing conditions.


Bob Kertesz
BlueScreen LLC
Hollywood, California
bob at bluescreen.com

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