Am 29.04.2010 18:24, schrieb Warp:

>    As for image map images which don't have gamma info in them, they have to
> be pre-gamma corrected manually when using the correct gamma for your system.
> POV-Ray 3.7 implements now a keyword to do that.

Actually you can typically go without explicitly using that mechanism, 
as POV-Ray will still make a sophisticated guess and perform an implicit 
gamma-adjustment which should be fine for most cases.

>    Question: If someone "lies" to POV-Ray by claiming that his system uses
> a gamma of 1.0 when in reality it uses a gamma of 2.2, and renders an image
> with that setting, will that image look the same in a different system with
> a different gamma (eg. one with a gamma of 1.8), or will it look different?
> If so, how different (brighter, darker...)?

It doesn't matter what POV-Ray settings were used to create the image 
file: An image file created with a "lie" will suffer exactly the same 
effects when transmitted to another system as an image file created 
without a "lie".

When moving an image file from a gamma 2.2 system to a gamma 1.8 system, 
the file may or may not look a tad brighter and more washed-out, 
depending on whether the file format carries gamma information, and/or 
whether the "target" system makes a correct guess that the image was 
created to look good on a gamma 2.2 system.

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"clipka" <ano### [at] anonymousorg> wrote in message 
news:4bd9de4e@news.povray.org...
> Am 29.04.2010 17:42, schrieb Quietman:
>
>> I find using the defaults (2.2?) produces very bright washed out files. 
>> The
>> best fix I have found so far is to set both gamma settings to 1. It makes
>> the renders look natural in tone and colour for me.
>
> I take a bold guess that this is probably because you're used to the way 
> older POV-Ray versions did it, and have developed an instinct how to 
> achieve the desired results for the old versions. Unfortunately that 
> instinct don't work with the /more realistic/ model used in 3.7.
>
> You may also have been fooled by earlier betas which couldn't handle input 
> images properly (they did indeed get those input images too bright and 
> washed-out).
>
> Well, I guess I'm trying to evangelize you here, but in the end it's your 
> choice of course.

If I use the default settings of 2.2 how do I make my renders look less 
washed out? I don't use anything fancy or complicated, usually one light 
coloured white... I really don't know what to do about this.

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Am 29.04.2010 23:23, schrieb Quietman:

> If I use the default settings of 2.2 how do I make my renders look less
> washed out? I don't use anything fancy or complicated, usually one light
> coloured white... I really don't know what to do about this.

There are several reasons why your scenes may look washed-out:
- Your pigments may simply be too bright and desaturated.
- You may be using too much ambient.
- Distance-based light fading (or absence thereof) might also play a role.

Note that virtually all the inc files and sample scenes were created for 
comparatively old versions of POV-Ray, so their materials are not really 
good for 3.7 unfortunately.

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clipka <ano### [at] anonymousorg> wrote:
> Note that virtually all the inc files and sample scenes were created for 
> comparatively old versions of POV-Ray, so their materials are not really 
> good for 3.7 unfortunately.

  Maybe that should be changed?

-- 
                                                          - Warp

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On 04/30/2010 08:07 AM, Warp wrote:
> clipka <ano### [at] anonymousorg> wrote:
>> Note that virtually all the inc files and sample scenes were created for 
>> comparatively old versions of POV-Ray, so their materials are not really 
>> good for 3.7 unfortunately.
> 
>   Maybe that should be changed?
> 
does that mean you're volunteering ;-)

Post a reply to this message

Am 30.04.2010 13:07, schrieb Warp:
> clipka<ano### [at] anonymousorg>  wrote:
>> Note that virtually all the inc files and sample scenes were created for
>> comparatively old versions of POV-Ray, so their materials are not really
>> good for 3.7 unfortunately.
>
>    Maybe that should be changed?

Definitely so.

Post a reply to this message

"Quietman" <quietman1968 at hotmail dot com> wrote:
> Hi,
>
> Just trying out beta 37 of povray and all output files are over bright
> compared with earlier versions.
>
> I always add the following lines to the end of my povray.ini file.
>
> ; .png Image Type by default
> Output_File_Type=N
>
> ; Picture brightness
> Display_Gamma=1
> File_Gamma=1
>
> The display seems ok but the output file is lighter, even with the default
> file type (BMP).
>
> Anyone else having trouble or is it my setup thats gone wrong somewhere?
>
> Cheers.
------------------------------------------------------------
Hello,

I have the same problems with PovRay 3.7 beta 37.
Previous beta version was OK for me : 3.7 beta 36. But for installation of beta
37 it was need to uninstall beta 36... Now all pictures are white...
I tried with this ini seetings:
====================================================================
; Persistence Of Vision raytracer version 3.5 sample file.
File_Gamma = 0.980
Display_Gamma = 0.980
Antialias=On
Sampling_Method=1
Antialias_Threshold=0.1
Antialias_Depth=4
Input_File_Name=name.pov
Output_Alpha=off
Output_File_Type=N   ;; S= bmp, T=uncompressed tga &  N png output
+w800
+h600

;+w3200
;+h2400
Cyclic_Animation=off
Pause_when_Done=on
===================================================================

But if "assumed_gamma 0.98" at 0.98, 1.00, 1.02, 2.0 ,2.2 is present in the .pov
file, same result in the picture : white.
It seems that we can obtain something right if we comment assumed_gamma value :
//assumed_gamma 0.98
in the .pov file
and if we use File_Gamma and Display_Gamma in the ini file.

Now, the modification of assumed_gamma "value" in the .pov file seems to have no
effect on the picture (display)

May it is possible to find beta 36 somewhere?

Many thanks for your advices.

Cheers,

JJ

Post a reply to this message

> "Quietman"<quietman1968 at hotmail dot com>  wrote:
>> Hi,
>>
>> Just trying out beta 37 of povray and all output files are over bright
>> compared with earlier versions.
>>
>> I always add the following lines to the end of my povray.ini file.
>>
>> ; .png Image Type by default
>> Output_File_Type=N
>>
>> ; Picture brightness
>> Display_Gamma=1
>> File_Gamma=1
>>
>> The display seems ok but the output file is lighter, even with the default
>> file type (BMP).
>>
>> Anyone else having trouble or is it my setup thats gone wrong somewhere?
>>
>> Cheers.
> ------------------------------------------------------------
> Hello,
>
> I have the same problems with PovRay 3.7 beta 37.
> Previous beta version was OK for me : 3.7 beta 36. But for installation of beta
> 37 it was need to uninstall beta 36... Now all pictures are white...
> I tried with this ini seetings:
> ====================================================================
> ; Persistence Of Vision raytracer version 3.5 sample file.
> File_Gamma = 0.980
> Display_Gamma = 0.980
> Antialias=On
> Sampling_Method=1
> Antialias_Threshold=0.1
> Antialias_Depth=4
> Input_File_Name=name.pov
> Output_Alpha=off
> Output_File_Type=N   ;; S= bmp, T=uncompressed tga&   N png output
> +w800
> +h600
>
> ;+w3200
> ;+h2400
> Cyclic_Animation=off
> Pause_when_Done=on
> ===================================================================
>
> But if "assumed_gamma 0.98" at 0.98, 1.00, 1.02, 2.0 ,2.2 is present in the .pov
> file, same result in the picture : white.
> It seems that we can obtain something right if we comment assumed_gamma value :
> //assumed_gamma 0.98
> in the .pov file
> and if we use File_Gamma and Display_Gamma in the ini file.
>
> Now, the modification of assumed_gamma "value" in the .pov file seems to have no
> effect on the picture (display)
>
> May it is possible to find beta 36 somewhere?
>
> Many thanks for your advices.
>
> Cheers,
>
> JJ
>
>

assumed_gamma is been phased out and obsolete.
Removing it, or commenting it out is the thing to do.

I don't see your problem on my side. In fact, the files I render with 
beta 37 are identical to the beta 36. But, I had the habit of removing 
any assumed_gamma before I started using any of the 3.7 betas.
In some scenes, I found some prety weird values, like 0.1, 5 or more, 
and some negative values...

Anyway, file_gamma and display_gamma should be set to the actual gamma 
value of your system. 0.980 very probably is not the real gamma of your 
system. Normaly, it's closer to 2.2.



Alain

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Alain <aze### [at] qwertyorg> wrote:

> assumed_gamma is been phased out and obsolete.
> Removing it, or commenting it out is the thing to do.
>
> I don't see your problem on my side. In fact, the files I render with
> beta 37 are identical to the beta 36. But, I had the habit of removing
> any assumed_gamma before I started using any of the 3.7 betas.
> In some scenes, I found some prety weird values, like 0.1, 5 or more,
> and some negative values...
>
> Anyway, file_gamma and display_gamma should be set to the actual gamma
> value of your system. 0.980 very probably is not the real gamma of your
> system. Normaly, it's closer to 2.2.
>
>
>
> Alain

Hello Alain,

Many thanks for your answer.
I tried to remove "assumed_gamma" in the .pov file. In both cases, with (value
0.8, 1.0 or 2.2) and without, the picture in the render povray window is the
same and the picture in the file picture (e.g. picture.bmp, png or tga) is very
bright washed out. I tried equally with and without radiosity and the same
results: very bright washed out files.
When I use as the first lines in the .ini file:
  File_Gamma = 0.98
  Display_Gamma = 0.98
or 1.0 or 2.2 I have the same problem:
gamma in the display povray window and the file picture (bmp, tga or png) is not
the same: very bright washed out files
But with this ini file, we can read equally in the message windows
    "Parse warning: gamma_correction not specified or inferred so is turned off
for compatibility with this pre POV-Ray 3.7 scene."

So how we can specify the same gamma for the render povray window and the file
picture?

Many thanks,

JJ

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> Alain<aze### [at] qwertyorg>  wrote:
>
>> assumed_gamma is been phased out and obsolete.
>> Removing it, or commenting it out is the thing to do.
>>
>> I don't see your problem on my side. In fact, the files I render with
>> beta 37 are identical to the beta 36. But, I had the habit of removing
>> any assumed_gamma before I started using any of the 3.7 betas.
>> In some scenes, I found some prety weird values, like 0.1, 5 or more,
>> and some negative values...
>>
>> Anyway, file_gamma and display_gamma should be set to the actual gamma
>> value of your system. 0.980 very probably is not the real gamma of your
>> system. Normaly, it's closer to 2.2.
>>
>>
>>
>> Alain
>
> Hello Alain,
>
> Many thanks for your answer.
> I tried to remove "assumed_gamma" in the .pov file. In both cases, with (value
> 0.8, 1.0 or 2.2) and without, the picture in the render povray window is the
> same and the picture in the file picture (e.g. picture.bmp, png or tga) is very
> bright washed out. I tried equally with and without radiosity and the same
> results: very bright washed out files.
> When I use as the first lines in the .ini file:
>    File_Gamma = 0.98
>    Display_Gamma = 0.98
> or 1.0 or 2.2 I have the same problem:
> gamma in the display povray window and the file picture (bmp, tga or png) is not
> the same: very bright washed out files
> But with this ini file, we can read equally in the message windows
>      "Parse warning: gamma_correction not specified or inferred so is turned off
> for compatibility with this pre POV-Ray 3.7 scene."
>
> So how we can specify the same gamma for the render povray window and the file
> picture?
>
> Many thanks,
>
> JJ
>
>

To set both to the same thing, use the same value in the ini file.

Set Display_Gamma to the gamma of your system. It sets the gamma for the 
preview.

Set File_Gama to that same value or 2.2

Maybe you have a problem with your viewer.


Alain

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