[Tig] Monitor calibration

Bob Friesenhahn bfriesen
Tue May 31 15:59:20 BST 2005

On Tue, 31 May 2005, Martin Euredjian wrote:
> [TV] Old SMPTE?:     32 to 35 (109.63 to 119.91)
> [TV] The "standard"?: 30 (102.78)
> [TV] Better resolution?: 26 to 28 (89.08 to 95.93)
> [TV] If you use the Sony calibration probe:  20 (68.52)
> [MP] Theaters are not bright: 12 to 16 (41.11 to 54.82)
>> From one end of this scale to the other there is a huge factor of 2 in white
> point light output.  The [MP] case is understandable, of course, but, how
> about the other cases?

The best results will be obtained when the viewing environment is most 
similar to the reference target environment.  One thing which confuses 
the issue is that while the standard for film shown in a theater is 
12FL, the same content may be delivered on DVD or HDTV and projected 
on a display device (e.g. DLP, LCD, Plasma) which is capable of high 
brightness and may be used in a brighter viewing environment.  In 
fact, except for legacy CRT, modern display devices for the home 
usually benefit from a brighter surround since black level 
reproduction is still poor and the brighter surround masks that 

> Notice I didn't mention black levels above.  The situation is even more
> confusing there.  Some seem to think that you need to set black to a
> beam-off condition.  Which, I'll stick my neck out and say, is absolutely
> wrong.  We can get into that later.

Yes, that would be silly.  Black level settings are all about 
reproduction. If particular numeric values are needed later then 
calibration data from the display can be used to transform to a 
standard color space.

> Others like to use the famous PLUGE (Picture-LineUp Generation Equipment)
> pulse. The problem with this, of course, is that it is just-about the worst
> in terms of repeatability.  It think it may be fair to say that no two
> people will set the PLUGE pulse the same way.  Everyone can repeat the

Even if the exact same procedure is followed, not everyone perceives 
the same thing.  PLUGE is based on perception and is done using the 
display and the human eye so its adjustment results in the most 
accurate setting for the viewing conditions under which the adjustment 
was made, and for the person who did the calibration.  If the person 
who normally uses the display also did the black level adjustment, 
then the adjustment will be most accurate for that person.

Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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