On 28/02/2015 15:56, James Holsenback wrote:
> then i should have replied to the OP inquiry about blue dress instead

Forgiven. ;-)

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Regards
     Stephen

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Am 28.02.2015 um 15:54 schrieb MichaelJF:

> But this would only explain one part of the black-blue vs. White-Gold riddle.

I think the enigma is easily explained as a combination of multiple effects.

First, the facts:

(1) One very obvious technical flaw of the image is that the background 
is hopelessly overexposed.

(2) The image has another (related?) technical flaw, in that there is a 
yellowish overlay across the entire image; this might be due to 
overexposure, stray light from a poor or dirty lens, an uncalibrated 
camera, some automatic whitepoint adjustment gone rogue, or a 
combination thereof. At any rate, it results in a significant shift in 
brightnss and colour contrast, and also some shift in hue, of the dress; 
thus, instead of pitch black and royal blue we all physically see a kind 
of brownish grey and pastel blue.

(3) Most viewers' displays and/or viewing environments are probably not 
calibrated, adding a multitude of other brightness, contrast and colour 
distortions, which differ between viewers.

Now, it all boils down to how individual people's brains make sense of 
the image, which is a result of the above different visual input 
combined with different viewer expectations. There are essentially three 
options:

(A) The brain correctly identifies the flaws of the original image, 
auto-correcting the colours of the dress back to the original royal blue 
& black.

(B) The brain takes the overexposured background as an indication that 
the image was taken against the light source, expecting the dress to be 
underexposed, and thus performing some auto-"correction" that in fact 
just enhances the effect to the point where the dress is seen as white & 
gold.

(C) The brain takes the colours of the dress at face value (to some 
degree, that is), seeing neither the original royal blue & deep black 
nor the reported white & gold, but a pastel blue & slightly brownish 
dark grey. (This is actually what my brain seems to be doing, at least 
when viewing the image on my super-duper calibrated display.)

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On Sat, 28 Feb 2015 17:56:48 +0200, James Holsenback <nom### [at] nonecom>  

wrote:

> On 02/28/2015 10:35 AM, Stephen wrote:
>> On 28/02/2015 14:56, James Holsenback wrote:
>>> On 02/28/2015 07:38 AM, Stephen wrote:
>>>> On 28/02/2015 12:01, Thomas de Groot wrote:
>>>>> On 28-2-2015 12:56, Le_Forgeron wrote:

>>>>>>> -Nekar Xenos-
>>>>>>>
>>>>>>>
>>>>>> It's only a variation of the checker board in the shadow of a
>>>>>> cylinder.
>>>>>>
>>>>>
>>>>> ???
>>>>>
>>>> +1
>>>>
>>>>
>>> http://www.nytimes.com/interactive/2015/02/28/science/white-or-blue-
dress.html?_r=0
>>>
>>>
>>
>>
>> Thanks Jim but I think that the ??? was for "the checker board in the

>> shadow of a cylinder"
>>
>> When I looked at the image I see gold and white with a tinge of blue.

>> And when I sampled the image on the BBC site the Gold was about
>> <125,109,73> and the other <130,136,187>, roughly.
>>
>
> then i should have replied to the OP inquiry about blue dress instead

I posted on chrome with my phone but now my OP doesn't show up on Opera 
 

Mail on my PC. Strange.

-- 

-Nekar Xenos-

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On Sat, 28 Feb 2015 13:56:37 +0200, Le_Forgeron <jgr### [at] freefr> wrot
e:


>> -Nekar Xenos-
>>
>>

SInce I can'te reply to myself, I'll post this here. It seems there was 
 

something that gave off a lot of yellow tint radiosity. Maybe there was 
a  

taxi behind the photographer. here's a quick scene that basically  

demonstrates the principle:




  // Persistence of Vision Ray Tracer Scene Description File
// based on Radiosity scene.pov
// Radiosity sample for POV-Ray version 3.7
//
// Based on a scene by Friedrich A. Lohmueller, Dec 2010
// Derived from a sample of Bob Hughes,2001
//----------------------------------------------------------------------
----
#version 3.7;
#default{ finish{ ambient 0.1 diffuse 0.9 }}
//----------------------------------------------------------------------
----
#default{ finish{ ambient 0 diffuse 1 }}
//------------------------------------------
#include "shapes.inc"
#include "colors.inc"
#include "textures.inc"
//------------------------------------------

global_settings{
   ambient_light 1
   radiosity {
          // pretrace_start 1
          // pretrace_end 1
           error_bound 0.6
           count 50
          // brightness 1
          // gray_threshold 0
          // media on
          // normal on
           recursion_limit 2
        } // --------------
  }// end global_settings
// ----------------------------------------



camera{ location  <0, 14, -20>
         right   x*image_width/image_height
         rotate 12*y
         look_at   <-1.25,2.8,0>
         angle 33
       }

sky_sphere{ pigment { color rgb <1,1,.1>*100} }

// fog  

---------------------------------------------------------------------

// ground  

------------------------------------------------------------------
plane{ <0,1,0>, 0
       pigment{ color rgb 1}

      } // end of plane
// -----------------------------------------
//box{-50,50 hollow pigment{colour rgb <1,1,0>}finish{diffuse 1}}

union {
#for (Cnt,1,3)
   difference {
      box {<-1,-1,-1>,<1,1,1> }
      sphere {0,1.40 inverse  }
      sphere {0,1.25}
      texture{ pigment{ color rgb ((Cnt/2)=(int(Cnt/2)))*<.1,.1,.7>+.0
3}//  

Blue/Black
               finish{ phong 1 diffuse 1-Cnt/10 }
             }
      translate<0,0,0>
      scale 1+Cnt*0.65
      translate <0,1+Cnt*0.30,0>
      rotate Cnt*<0,-22,0>
    }//----------
#end
scale <1,1,1>
translate<0,1,0>
}
// -----------------------------------------



-- 

-Nekar Xenos-

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On 28/02/15 18:36, clipka wrote:
<snip>

> 
> (C) The brain takes the colours of the dress at face value (to some
> degree, that is), seeing neither the original royal blue & deep black
> nor the reported white & gold, but a pastel blue & slightly brownish
> dark grey. (This is actually what my brain seems to be doing, at least
> when viewing the image on my super-duper calibrated display.)
> 

I hate to say this, but: Me too.

John
-- 
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children

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Am 28.02.2015 um 19:37 schrieb Nekar Xenos:

> I posted on chrome with my phone but now my OP doesn't show up on Opera
> Mail on my PC. Strange.

Maybe because your message comes without any body text, just a signature 
line?

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On 28-2-2015 16:35, Stephen wrote:
> On 28/02/2015 14:56, James Holsenback wrote:
>> On 02/28/2015 07:38 AM, Stephen wrote:
>>> On 28/02/2015 12:01, Thomas de Groot wrote:
>>>> On 28-2-2015 12:56, Le_Forgeron wrote:
>>>>> Le 28/02/2015 08:48, Nekar Xenos a écrit :
>>>>>> -Nekar Xenos-
>>>>>>
>>>>>>
>>>>> It's only a variation of the checker board in the shadow of a
>>>>> cylinder.
>>>>>
>>>>
>>>> ???
>>>>
>>> +1
>>>
>>>
>> http://www.nytimes.com/interactive/2015/02/28/science/white-or-blue-dress.html?_r=0
>>
>>
>
>
> Thanks Jim but I think that the ??? was for "the checker board in the
> shadow of a cylinder"

It was for the /blue dress/ initially, /and/ for the answer which did 
not make sense to me in that context. I am satisfied now :-)


-- 
Thomas

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> On Sat, 28 Feb 2015 13:56:37 +0200, Le_Forgeron <jgr### [at] freefr> wrote:
>

>>> -Nekar Xenos-
>>>
>>>
>
> SInce I can'te reply to myself, I'll post this here. It seems there was
> something that gave off a lot of yellow tint radiosity. Maybe there was
> a taxi behind the photographer. here's a quick scene that basically
> demonstrates the principle:
>
>

>       texture{ pigment{ color rgb
> ((Cnt/2)=(int(Cnt/2)))*<.1,.1,.7>+.03}// Blue/Black
>                finish{ phong 1 diffuse 1-Cnt/10 }
>              }

Maybe use srgb instead rgb...

-- 
Lionel
Do not judge my words, judge my actions.

---

http://www.avast.com

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