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From: Dave Blandston
Subject: POV Logo Wallpaper
Date: 29 Dec 2010 08:30:01
Message: <web.4d1b37a958e25535966554e20@news.povray.org>
Hi there,

Here's a variation of Chris Colefax's POV logo. I think it makes a simple but
colorful wallpaper.

Regards,
Dave Blandston


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Attachments:
Download 'povers2.png' (715 KB)

Preview of image 'povers2.png'
povers2.png


 

From: Dave Blandston
Subject: Re: POV Logo Wallpaper
Date: 29 Dec 2010 08:45:01
Message: <web.4d1b3b10bf984996966554e20@news.povray.org>
Whoa!!! Gamma problems again - sorry. If anyone's interested I'll fix it and
re-post the picture.

-Dave


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From: clipka
Subject: Re: POV Logo Wallpaper
Date: 29 Dec 2010 09:44:38
Message: <4d1b4956$1@news.povray.org>
Am 29.12.2010 14:43, schrieb Dave Blandston:
> Whoa!!! Gamma problems again - sorry. If anyone's interested I'll fix it and
> re-post the picture.

To me it looked good as posted.


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From: Thomas de Groot
Subject: Re: POV Logo Wallpaper
Date: 30 Dec 2010 03:03:09
Message: <4d1c3cbd$1@news.povray.org>
"Dave Blandston" <nomail@nomail> schreef in bericht 
news:web.4d1b37a958e25535966554e20@news.povray.org...
> Hi there,
>
> Here's a variation of Chris Colefax's POV logo. I think it makes a simple 
> but
> colorful wallpaper.
>

Is looking very good. One has to be careful of the needle points though. So 
easy to get hurt :-)  Seriuously: maybe they should be a little bit 
blunter...?

Thomas


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From: Dave Blandston
Subject: Re: POV Logo Wallpaper
Date: 31 Dec 2010 01:50:01
Message: <web.4d1d7cacbf984996cb6252d10@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 29.12.2010 14:43, schrieb Dave Blandston:
> > Whoa!!! Gamma problems again - sorry. If anyone's interested I'll fix it and
> > re-post the picture.
>
> To me it looked good as posted.

Internet Explorer shows it washed-out. Only the small preview looks right on my
computer. I'll check my settings...


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From: Dave Blandston
Subject: Re: POV Logo Wallpaper
Date: 31 Dec 2010 01:50:01
Message: <web.4d1d7d07bf984996cb6252d10@news.povray.org>
"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
> "Dave Blandston" <nomail@nomail> schreef in bericht
> news:web.4d1b37a958e25535966554e20@news.povray.org...
> > Hi there,
> >
> > Here's a variation of Chris Colefax's POV logo. I think it makes a simple
> > but
> > colorful wallpaper.
> >
>
> Is looking very good. One has to be careful of the needle points though. So
> easy to get hurt :-)  Seriuously: maybe they should be a little bit
> blunter...?
>
> Thomas

That's part of the original - I only added the indented glowing parts.


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From: clipka
Subject: Re: POV Logo Wallpaper
Date: 31 Dec 2010 04:31:05
Message: <4d1da2d9$1@news.povray.org>
Am 31.12.2010 07:48, schrieb Dave Blandston:

>>> Whoa!!! Gamma problems again - sorry. If anyone's interested I'll fix it and
>>> re-post the picture.
>>
>> To me it looked good as posted.
>
> Internet Explorer shows it washed-out. Only the small preview looks right on my
> computer. I'll check my settings...

 From what I can see in the PNG header, you're using pretty 
unconventional gamma settings. For starters, File_Gamma=1.0 is generally 
not a good idea as it leads to the Windows Explorer thumbnail preview 
appearing differently. And as a matter of fact it's usually the 
thumbnail preview that lies to you, unless you have an exceptionally 
uncommon display gamma.

My guess is that you're using File_Gamma=1.0 and Display_Gamma=1.0, 
while actually having a display with a gamma of around 2.2.

The Display_Gamma=1.0 will make the image look the same in 3.7 beta 
preview render as if you had used assumed_gamma 2.2 in 3.6 with 
Display_Gamma=2.2, while the File_Gamma=1.0 will not have any visible 
effect on PNG files (except for viewers that ignore gAMA chunks, such as 
Windows Explorer's thumbnail generator) - it will just make the output 
more susceptible to banding artifacts.

While it /may/ be that you adjusted your display for a gamma of 1.0, it 
is both uncommon (typical values are around 2.2, give or take) /and/ 
will make virtually all of your software display nonsense unless you 
also informed Windows of the fact (or each piece of software separately, 
but only few pieces of SW provide a means to tell them about your 
display gamma).

Whatever you're doing there regarding gamma, you're probably doing 
/something/ fundamentally flawed.

And it's likely that you have a different taste than me: I do prefer the 
washed-out version, especially for a wallpaper.


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From: Dave Blandston
Subject: Re: POV Logo Wallpaper
Date: 3 Jan 2011 01:40:00
Message: <web.4d216c89bf9849965f9997c70@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
>  From what I can see in the PNG header, you're using pretty
> unconventional gamma settings. For starters, File_Gamma=1.0 is generally
> not a good idea as it leads to the Windows Explorer thumbnail preview
> appearing differently. And as a matter of fact it's usually the
> thumbnail preview that lies to you, unless you have an exceptionally
> uncommon display gamma.
>
> My guess is that you're using File_Gamma=1.0 and Display_Gamma=1.0,
> while actually having a display with a gamma of around 2.2.
>
> The Display_Gamma=1.0 will make the image look the same in 3.7 beta
> preview render as if you had used assumed_gamma 2.2 in 3.6 with
> Display_Gamma=2.2, while the File_Gamma=1.0 will not have any visible
> effect on PNG files (except for viewers that ignore gAMA chunks, such as
> Windows Explorer's thumbnail generator) - it will just make the output
> more susceptible to banding artifacts.
>
> While it /may/ be that you adjusted your display for a gamma of 1.0, it
> is both uncommon (typical values are around 2.2, give or take) /and/
> will make virtually all of your software display nonsense unless you
> also informed Windows of the fact (or each piece of software separately,
> but only few pieces of SW provide a means to tell them about your
> display gamma).
>
> Whatever you're doing there regarding gamma, you're probably doing
> /something/ fundamentally flawed.
>
> And it's likely that you have a different taste than me: I do prefer the
> washed-out version, especially for a wallpaper.

I'm sure I am doing something wrong. In order to get everything looking good on
my monitor (CRT), I set the video card gamma to +1.0. If I set it lower or
higher I CANNOT get things to look right by adjusting the brightness and
contrast settings. If I set my video card to gamma 2.2 it looks absolutely
terrible.

You are right, I'm using POVRAY.INI settings "file_gamma=1.0" and
"display_gamma=1.0." I added "assumed_gamma 1.0" to the scene file. Everything
looks great on my computer (render preview and finished images displayed with
any program other than Internet Exporer) but .png images look washed out when
displayed in Internet Explorer. Between the video card settings, POVRAY.INI
settings, assumed_gamma setting, and monitor brightness settings something must
be wrong. (I don't think Windows XP has any gamma settings other than what the
video card driver adds.) But after lots of experimentation, the only thing that
doesn't work for me is the display of .png files with Internet Explorer so if I
convert to .jpg before posting everything will be fine.

By the way, even when I turn the file_gamma way down the image still appears
washed out in IE. I suspect there's something wrong with the way IE version 7
handles gamma. (At least it's different from all the other display programs I
use.)

Thanks for the tips!

Regards,
Dave Blandston


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From: clipka
Subject: Re: POV Logo Wallpaper
Date: 3 Jan 2011 06:19:06
Message: <4d21b0aa@news.povray.org>
Am 03.01.2011 07:36, schrieb Dave Blandston:

> I'm sure I am doing something wrong. In order to get everything looking good on
> my monitor (CRT), I set the video card gamma to +1.0. If I set it lower or
> higher I CANNOT get things to look right by adjusting the brightness and
> contrast settings. If I set my video card to gamma 2.2 it looks absolutely
> terrible.

There may be a potential for misunderstanding there: Your overall 
display gamma is the result of multiple component gammas - including the 
monitor, graphics card hardware, graphics card drivers, and even 
possibly some OS settings. The video card driver may - or may not - tell 
you only the "LUT gamma" (i.e. the graphics card driver's part of the 
whole thing). In that case a value of 1.0 is a pretty good setting, but 
is /not/ what you need to set POV-Ray's Display_Gamma to.

Did you ever check the gamma with the test images in the documentation, 
or some site on the internet? The 3.7.0.RC1 also comes with a section on 
gamma handling, and a sample scene to check whether your settings are 
"sane".

> You are right, I'm using POVRAY.INI settings "file_gamma=1.0" and
> "display_gamma=1.0." I added "assumed_gamma 1.0" to the scene file. Everything
> looks great on my computer (render preview and finished images displayed with
> any program other than Internet Exporer) but .png images look washed out when
> displayed in Internet Explorer. Between the video card settings, POVRAY.INI
> settings, assumed_gamma setting, and monitor brightness settings something must
> be wrong. (I don't think Windows XP has any gamma settings other than what the
> video card driver adds.) But after lots of experimentation, the only thing that
> doesn't work for me is the display of .png files with Internet Explorer so if I
> convert to .jpg before posting everything will be fine.
>
> By the way, even when I turn the file_gamma way down the image still appears
> washed out in IE. I suspect there's something wrong with the way IE version 7
> handles gamma. (At least it's different from all the other display programs I
> use.)

No, IE is probably the only piece of software you have that's doing it 
right.

 From all you tell me, I assume that your overall display gamma is 
indeed around 2.2, and that you're currently "cheating" your way around 
what assumed_gamma 1.0 is intended to do. Note that the combination 
Display_Gamma=File_Gamma=assumed_gamma=1.0 is virtually equivalent to 
Display_Gamma=File_Gamma=assumed_gamma=2.2 /except for PNG output/.

So here's what you should do:

(1) Check your display gamma, using one of the many gamma test patterns 
out there, such as the image in section 3.1.2.3.2 "Setting your Display 
Gamma" of the POV-Ray 3.6 docs, or using the sample scene mentioned in 
the tutorial section "Gamma Handling" of the 3.7.0.RC1 docs. I suspect 
you'll learn that your display gamma /is/ around 2.2.

(2) Set Display_Gamma=2.2 and File_Gamma=2.2

(2.1) Note that this will /always/ give you that washed-out appearence 
you're currently seeing with .png in IE.

(3) To compensate, either (a) go back to using assumed_gamma 2.2 (*), or 
(b) learn how to texture and illuminate your scene for physically 
accurate rendering, and/or (c) get used to the more washed-out look and 
learn to like it.

(* As of 3.7.0.RC1, assumed_gamma is no longer considered deprecated; to 
the contrary, it will be /mandatory/ in the future; and while the 
recommendation to use a value of 1.0 is still maintained for /physically 
accurate/ renders, it is now acknowledged that people may prefer other 
properties over physical accuracy. The new gamma handling features have 
also been adapted to play nice with assumed_gamma.)


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From: Jaime Vives Piqueres
Subject: Re: POV Logo Wallpaper
Date: 3 Jan 2011 07:05:11
Message: <4d21bb77@news.povray.org>

> I'm sure I am doing something wrong. In order to get everything looking good on
> my monitor (CRT), I set the video card gamma to +1.0. If I set it lower or
> higher I CANNOT get things to look right by adjusting the brightness and
> contrast settings. If I set my video card to gamma 2.2 it looks absolutely
> terrible.
>

   While I agree totally with clipka remarks, I think perhaps your CRT 
is also to blame here... your issues remember me of my problems many 
years ago with a faulty Samsung monitor. I suspect this is why you see 
as "washed out" what others see as "correct", and also why others see as 
"too dark" what you see as "correct".

   Look for example at this old image of mine, which I created while 
using the flawed monitor:

   http://www.ignorancia.org/uploads/images/persiana/persiana.jpg

   Back then it looked fine to me: I was even able to see the plant on 
the corner! Now, with a properly calibrated monitor, I can barely see 
anything else than the sunlit parts and a little radiosity near them. 
How do you see it? ...do you see the plant on the corner?


-- 
Jaime Vives Piqueres
		
La Persistencia de la Ignorancia
http://www.ignorancia.org


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