Warp <war### [at] tagpovrayorg> wrote:
> (The gray stripe at the bottom still looks to me
> like biased too bright, but maybe it's a question of getting used to it.)

  Btw, I asked a friend in IRC (completely without any kind of leading),
and he too thought that the bottom stripe was too biased towards the bright
side. I don't know what causes this perception.

-- 
                                                          - Warp

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Warp schrieb:
>   You are seriously claiming that my display is way, way too bright.
> That really makes me laugh out loud.

Do so if that makes you feel any better.

All I see from my side is that it looks perfect, and I'm quite confident 
that my display calibration goes beautifully well with my operating 
system as well as my image viewing and manipulation software.

>   If anything, my display is too dark. Often images posted by people in
> p.b.images look almost black. When I complain about it, others say they
> can see it just fine.
> 
>   Now you are telling me that I have to calibrate my monitor to be something
> like 25% darker than it already is. Everything in the darker 20% or so
> darkest color space would become completely black and invisible.

Calibration isn't just about turning a monitor brighter or darker. It's 
about adjusting (A) the black point, (B) the white point, (C) the gamma, 
and if your display is particularly bad or you need particularly good 
calibration, even (D) the exact display curve for the individual color 
components.

I don't know what's wrong with your display. Go check it out, use the 
display adjustment tools that came with your graphics card, or google 
for some tools on the net, or whatever. But stop griping about POV-Ray 
being wrong when really you got your image viewing pipeline gamma 
crapped up.

>   Are you also seriously claiming that the starfield image in the pov3.7
> rendered image looks just fine? Does that mean that the original looks like
> a black square with some tiny white pixels here and there in your monitor?

No, I'm not claiming that. You may have noticed that I already mentioned 
that the /input/ file gamma of POV-Ray (both 3.6 and 3.7) is bogus at 
least for some file formats (JPEG is among those). That's where /that/ 
comes from

>> So stop your griping, disengage "demand mode", calibrate your image 
>> viewing pipeline properly, and /then/ come back with any residual problems.
> 
>   I don't appreciate your condescending tone of voice. I'm trying to discuss
> about an issue here.

If you were trying to discuss, then you should be less demaning. All I 
hear is "Please explain this again, please tell me that, please give me 
advice about yonder thing", and griping about me allegedly not 
explaining anything, which I'm trying my best to do though.

>> As for entering gamma-pre-corrected colors into POV-Ray, you might use 
>> something like this:
> 
>>    #macro UnGamma(C)
>>      #local G = 1/2.2;
>>      <pow(C.red,G),pow(C.green,G),pow(C.blue,G),C.filter,C.transmit>
>>    #end
> 
>>    #declare MyGrey = UnGamma(rgb <127,127,127>/255);
> 
>   I don't get it. The image POV-Ray 3.7 is producing by default is way too
> bright, and you want me to brighten the colors even further? (For example
> rgb 0.1 becomes rgb 0.35, rgb 0.5 becomes rgb 0.73.)

Maybe I just got the math wrong way round, huh? Now STFU and do some 
thinking for yourself. If you understand enough about gamma to be so 
sure that POV-Ray 3.7 does it wrong, then you shouldn't have any 
difficulties to figure out how to straighten up the math and turn that 
macro into something useful. I owe you no support on this one, as I'm 
not even remotely responsible for you being unhappy with POV-Ray's gamma 
handling. If you honestly request information and have any hope of me 
being able to provide it, please switch into a different mode showing at 
least a /bit/ of appreciation for me taking time to answer, and a /bit/ 
of willingness to listen and understand, or otherwise don't bother to 
continue asking me about it if you deem my answers worthless.

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clipka <ano### [at] anonymousorg> wrote:
> Maybe I just got the math wrong way round, huh? Now STFU and do some 
> thinking for yourself. If you understand enough about gamma to be so 
> sure that POV-Ray 3.7 does it wrong, then you shouldn't have any 
> difficulties to figure out how to straighten up the math and turn that 
> macro into something useful.

  I find it a bit hypocritical for you to criticize me and tell me to shut
the fuck up when even you can't get the math right.

  Normally criticizing how someone is wrong, correcting them, and then
making yourself a blunder in the precise subject you are lecturing about
should be a lesson in humility, but I assume that would be too much to hope.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
>   So yes: I now see how the gamma correction of 2.2 changes the rgb 0.5 to
> a shade which closely matches half brightness emulated with alternating
> black and white lines.

  (Btw, IMO there still should be a way of telling POV-Ray to not gamma
correct anything if that's what the user wishes. Currently it seems to
be difficult, as POV-Ray seems to be writing a gamma value of 2.2 to the
output PNG file regardless of what File_Gamma is. I don't even understand
where it's getting that 2.2 value from.)

-- 
                                                          - Warp

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Warp wrote:
> Warp <war### [at] tagpovrayorg> wrote:
>>   Now the lower half of the rendered images is a checkerboard pattern of
>> alternating black and white pixels.
> 
>   There was a warning somewhere that a checkerboard patter should *not* be
> used for this kind of test because it doesn't work properly with CRT
> monitors. Instead, alternating horizontal lines should be used instead.

I have an LCD monitor, and the checkerboard looked *green*. Quite strange.

Now with the horizontal stripes. POV3.6 looks too dark and POV3.7 looks too
light.

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Nicolas Alvarez <nic### [at] gmailcom> wrote:
> Now with the horizontal stripes. POV3.6 looks too dark and POV3.7 looks too
> light.

  As I already wrote, now that I'm using the proper test (at least for CRT
monitors, which is what I have), I must admit that the 3.7 image background
looks very even with my monitor. I suppose that my monitor does indeed
require a gamma correction of almost exactly 2.2 for proper brightness,
and that my system settings were correct to begin with.

  On the other hand, I'm wondering how precise this test really is.
Bright white lines stand out a lot more than black lines, and the brighter
the white lines are, the more they tend to glow to the human eye. A bit
like color bleeding. This would mean that if your monitor is set very
bright, then the white lines will overwhelm the black ones, requiring
a different gamma correction value than if your monitor was set to a
very dim setting, in which case the white lines won't stand out that much
compared to the black lines.

-- 
                                                          - Warp

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Warp wrote:
> This would mean that if your monitor is set very
> bright, then the white lines will overwhelm the black ones, requiring
> a different gamma correction value 

Isn't this kind of the point, tho? Unless you turn up both the black level 
and the white level in a controlled way, I'd think increasing the brightness 
of one or the other is going to mean you have to correct your images 
differently for them to "look right".

-- 
   Darren New, San Diego CA, USA (PST)
   Understanding the structure of the universe
    via religion is like understanding the
     structure of computers via Tron.

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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > This would mean that if your monitor is set very
> > bright, then the white lines will overwhelm the black ones, requiring
> > a different gamma correction value 

> Isn't this kind of the point, tho? Unless you turn up both the black level 
> and the white level in a controlled way, I'd think increasing the brightness 
> of one or the other is going to mean you have to correct your images 
> differently for them to "look right".

  What I meant is that, at least it seems to me, this phenomenon would be
exclusive to this precise test (in other words, alternating black/white
horizontal lines) and might not correspond to what is intended to be a
"50% gray" in an image would really look like on your monitor.

  Or if I try to express myself more clearly: Could it be that this
precise test (the horizontal lines) gives you the wrong impression of
what the proper gamma setting for your monitor would really be, this
visual impression being biased by the brightness setting of the monitor?

  If you used a completely different test, eg. physical pieces of paper
colored appropriately, would you end up with the same gamma setting?

-- 
                                                          - Warp

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Warp wrote:
>   What I meant is that, at least it seems to me, this phenomenon would be
> exclusive to this precise test 

I see. That makes more sense, yes.

-- 
   Darren New, San Diego CA, USA (PST)
   Understanding the structure of the universe
    via religion is like understanding the
     structure of computers via Tron.

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Warp schrieb:
>   I find it a bit hypocritical for you to criticize me and tell me to shut
> the fuck up when even you can't get the math right.

That's what happens when one gets annoyed by the other one not 
listening, alleging that one is "explaining nothing at all", and being 
extraordinarily demanding: It drastically reduces the motivation to 
invest time into it.

Besides it would be more humiliating for me if I didn't know already 
that I keep getting the exponent wrong way round.

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