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"Warp"  schreef in bericht news:4cf762ae@news.povray.org...

On 12/02/2010 02:01 AM, Jaap Frank wrote:
> That's odd, because for me the 3.6 side is correct and the 3.7 side is
> far too bright.
> I've a rather new HD LCD TFT monitor (about 6 months) and adjusted it
> conform the windows 7 system with brightness and contrast followed by
> color shade correction.
> Further the monitor of my laptop (Acer Aspire, 1 year old, crystal clear
> display) shows exactly the same picture. Both are driven by the NVidia
> card inside the laptop, so they should be the same and for /me/ they
> are. The pictures are displayed by Windows Live Mail.

  Note that at least with some LCD displays (especially on some laptops)
the angle from which you look at the screen affects the brightness. For
example, if I look at the image I posted in a MacBook laptop, I can
"tune" the "gamma correction" of the display by tilting the screen back
or forth (thus changing the vertical angle from which I look at the
screen). At some angles it looks like the brightness of the sides
correspond to the center of the 3.6 gradient (and thus the 3.7 gradient
is too bright), while at other angles it looks like they correspond to
the center of the 3.7 gradient (and thus the 3.6 gradient looks too
dark). (And everything in-between, of course.) This tells me that the
screen on this laptop is an *extremely* poor tool to determine which one
is correct (if either), because I can change it by simply looking at it
from a higher or a lower angle.

  I do understand, however, that many of the more modern and expensive
LCD displays don't suffer from this problem (at least not as badly).

  If I had a working camera I could take photos to corroborate these
findings, but unfortunately I don't.
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So I did some physical training. I tilted my display screens in any 
direction you can imagine, even held them up side down and on their sides, 
but while the light impression change with extreem angles, the result is 
always the same, 3.6 halfway the gradient and 3.7 somewhere around the 
second and third from the dark side. So the problem couldn't be the tilting 
angle.

Yve wrote somewhere in this thread that you can choose the color space. I 
found it and choose another possibility, but it didn't change much. It's now 
a tiny fraction in favor of the 3.7 side. For those who want to experiment 
with it:
Windows 7 (and probably Vista):  Control Panel > Appearances & 
Personalisation > Screen Resolution > Advanced Settings > Color Management 
(> Advanced > Calibrate Display).
Win XP: Search your Screen Resolution in Display, the rest is identical.
In 7 there are different Color spaces, but I think that the ICC profiles 
(these are for displays) are the only ones you can use. Maybe Yve can 
comment on that. In 7 there are two of theme and in XP there is one choice.
If you want to calibrate your screen then use the last part between the 
braces (7 only).

So, somewhat wiser, but not further. The next thing I tried was the color 
gamma of the video card. NVidia gives the possibility to change the gamma 
per color. Because I haven't a picture for the colors I first open't Paint 
Shop Pro 6 and in Files > Preferences > Monitor gamma there are three color 
bars and a B&W-bar, so you can adjust the gamma's. These values I used in 
the NVideo program and check it with PSP6 again. In PSP these are now all 
around one value, so my monitors are correctly calibrated.

Back to the picture of Warp: No change at all. Still 3.6 is correct and 3.7 
is not correct.

My conclusion is that the problem lies somewhere else and is NOT a problem 
of the monitors. In another computer with a rather expensive BenQ monitor 
(LCD) the results are exactly the same (Win XP and another NVidia card).

Can anyone check my results and answer here?

Jaap Frank

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