POV-Ray : Newsgroups : povray.general : What should gamma be? Server Time
10 Aug 2024 07:13:15 EDT (-0400)
  What should gamma be? (Message 1 to 10 of 12)  
Goto Latest 10 Messages Next 2 Messages >>>
From: Greg M  Johnson
Subject: What should gamma be?
Date: 23 Feb 2000 13:27:45
Message: <38B425B0.73242356@my-dejanews.com>
I have seen the web page that direct one to turn contrast & brightness
up to max to determine one's gamma.

Questions:
1) Are yall running your monitors all day long with max contrast &
brightness?
2) What gamma SHOULD I shoot for?

My problem is that I think I'm a bit darker than everyone else, and want
an objective, numerical way to standardize my viewing settings.


Post a reply to this message

From: ingo
Subject: Re: What should gamma be?
Date: 23 Feb 2000 13:55:26
Message: <8EE3C9766seed7@204.213.191.228>
Greg M. Johnson wrote:

>My problem is that I think I'm a bit darker than everyone else, and want
>an objective, numerical way to standardize my viewing settings.
>
Have you looked at the gamma.gif and gamma.txt at the end of the download 
area of povray.org?


Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


Post a reply to this message

From: Greg M  Johnson
Subject: Re: What should gamma be?
Date: 23 Feb 2000 15:19:01
Message: <38B43FC3.BEFFBE88@my-dejanews.com>
Yes, but:

1) it talks about turning up the monitor all the way up for contrast and
brightness to determine the gamma: is this the way you run all day long? If I
turn it down, I get a different number...
2) what number is the industry standard.

Thanks, I think you directed me to those pages months ago, but I'm still
lost.  I think that gamma is a weak function of one's monitor's build and a
strong function of the numbers one chooses.

I think I have a problem which will be solved by getting a correct gamma.
The problem is that a lot of work from other people looks crappily dark to
me, and my own work looks crappily dark when printed.  Some winning IRTC
entries look supercool and superphotorealistic, but just WAY too dark. One
example is Gail Shaw's 2/16/00 p.b.i offering.   I think that if I somehow
adopted the right gamma,  all these entries that other people like would look
nice to me, maybe I'd even get better prints of my own work!

Educate me!

ingo wrote:

> Greg M. Johnson wrote:
>
> >My problem is that I think I'm a bit darker than everyone else, and want
> >an objective, numerical way to standardize my viewing settings.
> >
> Have you looked at the gamma.gif and gamma.txt at the end of the download
> area of povray.org?
>
> Ingo
>
> --
> Photography: http://members.home.nl/ingoogni/
> Pov-Ray    : http://members.home.nl/seed7/


Post a reply to this message

From: Kari Kivisalo
Subject: Re: What should gamma be?
Date: 23 Feb 2000 15:41:56
Message: <38B44806.1D488514@kivisalo.net>
"Greg M. Johnson" wrote:

> 1) Are yall running your monitors all day long with max contrast &
> brightness?

Here is a test image for correct adjustments. Make sure that the
viewer doesn't apply any corrections.
http://hammer.prohosting.com/~kkivisal/adjust.gif

The image was ripped from Nokia's fine monitor test software.
http://www.nokia.com/monitors/download/ntest.html

Note that contrast is really the brightness adjustment and brighness
is actually black level. When room light level changes adjust
contrast only to compensate. When changing desktop resolution or
refresh rate readjusting is needed.

> 2) What gamma SHOULD I shoot for?

It seems that gamma 2.2 is the new standard for Internet. If your
display adapter has gamma adjustment you can measure the gamma
with the POV gamma image and then enter your_gamma/2.2 to the gamma
control panel. Then adjust with adjust.gif. Now your monitor simulates
gamma 2.2 monitor. Test it again with the POV gamma image to be sure.
Then you can put Display_Gamma=2.2 to your master povray.ini.

> My problem is that I think I'm a bit darker than everyone else, and want
> an objective, numerical way to standardize my viewing settings.

I'm so glad that someone actually worries about this :)

The only way to do it objectively is to use a luminance meter
to get the actual response of the monitor and go from there
but using the gamma test image is a step in the right direction.


-----------------------------------------------------------------------
Kari Kivisalo                                          www.kivisalo.net


Post a reply to this message

From: ingo
Subject: Re: What should gamma be?
Date: 23 Feb 2000 16:39:24
Message: <8EE3EFB65seed7@204.213.191.228>
Greg M. Johnson wrote:

>Yes, but:
>
>1) it talks about turning up the monitor all the way up for contrast and
>brightness to determine the gamma: is this the way you run all day long?
>If I turn it down, I get a different number...
>2) what number is the industry standard.
>
>Thanks, I think you directed me to those pages months ago, but I'm still
>lost.  I think that gamma is a weak function of one's monitor's build
>and a strong function of the numbers one chooses.
>
>I think I have a problem which will be solved by getting a correct
>gamma. The problem is that a lot of work from other people looks
>crappily dark to me, and my own work looks crappily dark when printed. 
>Some winning IRTC entries look supercool and superphotorealistic, but
>just WAY too dark. One example is Gail Shaw's 2/16/00 p.b.i offering.  
>I think that if I somehow adopted the right gamma,  all these entries
>that other people like would look nice to me, maybe I'd even get better
>prints of my own work! 
>
>Educate me!

Maybe the gamma-faq can help you better.
http://www.inforamp.net/~poynton/Poynton-color.html

I set the contrast once and adjust the brightness according to the 
intensity of the room illumination.

Dark, or overly bright pictures, do not mean that your gamma is wrong. Its 
just that the pictures gamma is not the same as your monitors, or printers. 

I don't think it is possible (with Windows) to change the gamma of your 
system, its determined by the graphics card and monitor, as explained in 
the pov documentation under "Monitor Gamma".

That is for me the reason to not view pictures in my newsreader, but use 
Irfanview. Always just one shortcut away from the gamma control slider.


Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


Post a reply to this message

From: ingo
Subject: Re: What should gamma be?
Date: 23 Feb 2000 16:46:33
Message: <8EE3E4696seed7@204.213.191.228>
ingo wrote:

>I set the contrast once and adjust the brightness according to the 
>intensity of the room illumination.

Aargh, that ofcourse I do the other way around. Fix brightness and vary 
contrast.

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


Post a reply to this message

From: Bob Hughes
Subject: Re: What should gamma be?
Date: 23 Feb 2000 18:48:32
Message: <38b471d0@news.povray.org>
Heck no, you don't want to run the monitor at highest contrast since you'd
probably get a bad looking screen and ruin your monitor  :-)
If the number you get isn't 2.2 for that test then that's why you do the test in
the first place, to find out if it's actually needing to be different.  You're
supposed to readjust the brightness or contrast (I forget which) after turning
it all the way up or down anyway, not leave it at max or min.
And I think you set the Display_Gamma= in the Povray.ini file to the number you
find is most correct.  At least I think so, or it's the assumed_gamma you adjust
with, I'm not at all sure.  Luckily mine turned out to be 2.1 so it was probably
isn't too drastic a change (but I did set the Display_Gamma in the INI file.
I could have tried readjusting gamma in the video card software but it was too
close to 2.2 for messing with that I figured.
I have my brightness knob (yep the old-fashioned non-digital kind) 1 turn from
the dark end out of three turns in total (so 1/3 brightness).  The contrast knob
is 1/3 the way from most contrast (whiter whites, blacker blacks) end of the
potentiometer.  Which has always been typical of my monitor settings of the past
3 I've owned.

Bob

"Greg M. Johnson" <gre### [at] my-dejanewscom> wrote in message
news:38B43FC3.BEFFBE88@my-dejanews.com...
| Yes, but:
|
| 1) it talks about turning up the monitor all the way up for contrast and
| brightness to determine the gamma: is this the way you run all day long? If I
| turn it down, I get a different number...
| 2) what number is the industry standard.
|
| Thanks, I think you directed me to those pages months ago, but I'm still
| lost.  I think that gamma is a weak function of one's monitor's build and a
| strong function of the numbers one chooses.
|
| I think I have a problem which will be solved by getting a correct gamma.
| The problem is that a lot of work from other people looks crappily dark to
| me, and my own work looks crappily dark when printed.  Some winning IRTC
| entries look supercool and superphotorealistic, but just WAY too dark. One
| example is Gail Shaw's 2/16/00 p.b.i offering.   I think that if I somehow
| adopted the right gamma,  all these entries that other people like would look
| nice to me, maybe I'd even get better prints of my own work!
|
| Educate me!
|
| ingo wrote:
|
| > Greg M. Johnson wrote:
| >
| > >My problem is that I think I'm a bit darker than everyone else, and want
| > >an objective, numerical way to standardize my viewing settings.
| > >
| > Have you looked at the gamma.gif and gamma.txt at the end of the download
| > area of povray.org?
| >
| > Ingo
| >
| > --
| > Photography: http://members.home.nl/ingoogni/
| > Pov-Ray    : http://members.home.nl/seed7/
|
|
|


Post a reply to this message

From: Ken
Subject: Re: What should gamma be?
Date: 24 Feb 2000 01:26:23
Message: <38B4CEAF.18BF2FC1@pacbell.net>
"Greg M. Johnson" wrote:
> 
> I have seen the web page that direct one to turn contrast & brightness
> up to max to determine one's gamma.
> 
> Questions:
> 1) Are yall running your monitors all day long with max contrast &
> brightness?

NO !!! Bad !!! If you have an image up with black areas that are grey
you have your brightness and contrast over saturated. Turn them down
until the monitor is easy to view and black areas are truly black.

***Your monitor is not a light bulb and should not be viewed like it is.

For a rather comprehensive source of information on POV-Ray and monitor
gamma visit this web site http://www.dlugosz.com/POV/Gamma/index.html

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


Post a reply to this message

From: Greg M  Johnson
Subject: ?? Mac is Mac and PC is PC and never the twain shall meet ??
Date: 24 Feb 2000 09:07:06
Message: <38B53A18.9EA02466@my-dejanews.com>
Thanks, I will do some more tweaking and reading.

Here's a question, re: Gail Shaw's  Wed, 16 Feb 2000 09:06:53 +0200  posting on
p.b.i.  I think that there is a high degree of compositional, technical, and
artistic merit. But it's bloody dark, especially after I turned my monitor down from
highest contrast! ;-p

Could this just be the great gap between Mac and Wintel: they define brightness per
pixel differently and thus what looks good on Mac won't look good on Wintel, no
matter how much I tweak my monitor settings.....


Bob Hughes wrote:

> Heck no, you don't want to run the monitor at highest contrast since you'd
> probably get a bad looking screen and ruin your monitor  :-)


Post a reply to this message

From: Chris Huff
Subject: Re: ?? Mac is Mac and PC is PC and never the twain shall meet ??
Date: 24 Feb 2000 16:00:09
Message: <chrishuff_99-553419.16013324022000@news.povray.org>
In article <38B53A18.9EA02466@my-dejanews.com>, 
gre### [at] my-dejanewscom wrote:

> Could this just be the great gap between Mac and Wintel: they define 
> brightness per pixel differently and thus what looks good on Mac 
> won't look good on Wintel, no matter how much I tweak my monitor 
> settings.....

The "standard" gamma on Macs is somewhere around 1.8, while PC's usually 
are in the area of 2.2. I think PNG format images contain gamma 
information, and if you use a reader which supports it, the display of 
the image will automatically be adjusted. I could easily be wrong 
though...

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/


Post a reply to this message

Goto Latest 10 Messages Next 2 Messages >>>

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.