POV-Ray : Newsgroups : povray.bugreports : Grayscale_Output=yes doesn't work Server Time
22 Jul 2024 11:08:36 EDT (-0400)
  Grayscale_Output=yes doesn't work (Message 2 to 11 of 11)  
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From: Le Forgeron
Subject: Re: Grayscale_Output=yes doesn't work
Date: 13 Mar 2015 19:57:44
Message: <55037978$1@news.povray.org>
Le 13/03/2015 23:33, Leroy a écrit :
> I've got
>  Micrsoft Windows XP
>  Home Edition
>  Version 2002
>  Service Pack 2
>  Intel(R) Pentium(R) Dual CPU
>   E2160 @ 1.80GHz
>  1.79Ghz, 0.99 GB of RAM
> 
> Pov version 3.7.0Rc7.msvc10-sse2.win32
> 
> I've tried putting it in the ini like the docs say.
> I've put in the the comand line option windows has.
> I even change the version to 3.6 and put 'hf_gray_16 in global_settings.
> I haven't try to output to a file (there's no point if you can't display
> it).
> Any Ideals?

As stated in the doc: hg_gray_16 is deprecated, and no more effective
with 3.7 (even in compatibility mode).

http://wiki.povray.org/content/Reference:Global_Settings

Grayscale_Output need a png or ppm output format.

I would concede that despite the documentation, the preview is not
greyscale (at least on my linux). But the output image is greyscale, and
16 bits.

gray.ini
********
Grayscale_output=true



gray.pov
********
#version 3.7
global_settings { assumed_gamma 1.0 }

camera { location <0,0,-100>
up y
direction z
right image_width/image_height*x
}

sphere { 0, 30 texture { pigment { color red 1 } finish { emission 0.5 } } }
light_source { <40,-30,-20>*20, 1 }



Command-line
************
povray gray.ini -Igray.pov


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From: Leroy
Subject: Re: Grayscale_Output=yes doesn't work
Date: 14 Mar 2015 12:34:56
Message: <55046330@news.povray.org>
Le_Forgeron wrote:
 > I would concede that despite the documentation, the preview is not
 > greyscale (at least on my linux). But the output image is greyscale, 
 >and 16 bits.

So is this a document thing or a bug?
My bet is a bug.


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From: clipka
Subject: Re: Grayscale_Output=yes doesn't work
Date: 15 Mar 2015 01:09:52
Message: <55051420$1@news.povray.org>
Am 14.03.2015 um 18:34 schrieb Leroy:
> Le_Forgeron wrote:
>  > I would concede that despite the documentation, the preview is not
>  > greyscale (at least on my linux). But the output image is greyscale,
>  >and 16 bits.
>
> So is this a document thing or a bug?
> My bet is a bug.

Nope; it is the documentation that is in error.

Making the preview exactly reflect the output image in every respect 
would be excessively difficult. (As an extreme example, reproducing jpeg 
artifacts according to the quality settings chosen would require to 
actually generate the jpeg image and then convert it back. Obviously 
that can only happen once the image is completely rendered. The same 
goes for some dithering options at low bit depths.) For consistency, it 
is therefore the current policy to always preview the render at maximum 
quality regardless of the output file format and quality parameters.

In that context, the question whether the output image contains any 
chromaticity information at all is currently considered a matter of 
output file format and quality.


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From: James Holsenback
Subject: Re: Grayscale_Output=yes doesn't work
Date: 15 Mar 2015 09:09:07
Message: <55058473@news.povray.org>
On 03/15/2015 01:09 AM, clipka wrote:
> Am 14.03.2015 um 18:34 schrieb Leroy:
>> Le_Forgeron wrote:
>>  > I would concede that despite the documentation, the preview is not
>>  > greyscale (at least on my linux). But the output image is greyscale,
>>  >and 16 bits.
>>
>> So is this a document thing or a bug?
>> My bet is a bug.
>
> Nope; it is the documentation that is in error.

http://wiki.povray.org/content/Reference:Global_Settings#HF_Gray_16

of course you all will let me know if i didn't get it right ;-)


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From: Leroy
Subject: Re: Grayscale_Output=yes doesn't work
Date: 16 Mar 2015 13:02:05
Message: <55070c8d$1@news.povray.org>
clipka wrote:
> Am 14.03.2015 um 18:34 schrieb Leroy:
>> So is this a document thing or a bug?
>> My bet is a bug.
> 
> Nope; it is the documentation that is in error.

I lost my bet! Never been good at gambling anyway.

> 
> Making the preview exactly reflect the output image in every respect 
> would be excessively difficult. (As an extreme example, reproducing jpeg 
> artifacts according to the quality settings chosen would require to 
> actually generate the jpeg image and then convert it back. Obviously 
> that can only happen once the image is completely rendered. The same 
> goes for some dithering options at low bit depths.) 

For consistency, it
> is therefore the current policy to always preview the render at maximum 
> quality regardless of the output file format and quality parameters.
So does that means the display option +Dxy have deprecated functions too?


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From: clipka
Subject: Re: Grayscale_Output=yes doesn't work
Date: 16 Mar 2015 15:43:37
Message: <55073269$1@news.povray.org>
Am 16.03.2015 um 19:01 schrieb Leroy:

>> Making the preview exactly reflect the output image in every respect
>> would be excessively difficult. (As an extreme example, reproducing
>> jpeg artifacts according to the quality settings chosen would require
>> to actually generate the jpeg image and then convert it back.
>> Obviously that can only happen once the image is completely rendered.
>> The same goes for some dithering options at low bit depths.)
>
>> For consistency, it
>> is therefore the current policy to always preview the render at
>> maximum quality regardless of the output file format and quality
>> parameters.
> So does that means the display option +Dxy have deprecated functions too?

Um... actually, no: In the Windows version they don't have any functions 
at all :P (Don't know about Unix off the top of my hat, but there it 
either does something non-deprecated, or nothing at all either.)

Those options certainly date back to the DOS versions (or even earlier).


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From: Leroy
Subject: Re: Grayscale_Output=yes doesn't work
Date: 16 Mar 2015 19:42:34
Message: <55076a6a@news.povray.org>
clipka wrote:
>> So does that means the display option +Dxy have deprecated functions too?
> 
> Um... actually, no: In the Windows version they don't have any functions 
> at all :P (Don't know about Unix off the top of my hat, but there it 
> either does something non-deprecated, or nothing at all either.)
> 
> Those options certainly date back to the DOS versions (or even earlier).
> 
Another thing the documentation needs updating.:) I had to check, the -D 
display option works OK. Thats all I really need anyway. I like for long 
animation runs.


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From: James Holsenback
Subject: Re: Grayscale_Output=yes doesn't work
Date: 17 Mar 2015 07:02:48
Message: <550809d8$1@news.povray.org>
On 03/16/2015 03:43 PM, clipka wrote:
> Am 16.03.2015 um 19:01 schrieb Leroy:
>
>>> Making the preview exactly reflect the output image in every respect
>>> would be excessively difficult. (As an extreme example, reproducing
>>> jpeg artifacts according to the quality settings chosen would require
>>> to actually generate the jpeg image and then convert it back.
>>> Obviously that can only happen once the image is completely rendered.
>>> The same goes for some dithering options at low bit depths.)
>>
>>> For consistency, it
>>> is therefore the current policy to always preview the render at
>>> maximum quality regardless of the output file format and quality
>>> parameters.
>> So does that means the display option +Dxy have deprecated functions too?
>
> Um... actually, no: In the Windows version they don't have any functions
> at all :P (Don't know about Unix off the top of my hat, but there it
> either does something non-deprecated, or nothing at all either.)
>
> Those options certainly date back to the DOS versions (or even earlier).
>

as far as i can tell the video_mode and palette options have no effect 
and produce no warning etc, so they've been removed:

http://wiki.povray.org/content/Reference:Display_Output_Options#Display_Hardware_Settings


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From: Le Forgeron
Subject: Re: Grayscale_Output=yes doesn't work
Date: 17 Mar 2015 13:03:37
Message: <55085e69$1@news.povray.org>
Le 17/03/2015 12:02, James Holsenback a écrit :
> On 03/16/2015 03:43 PM, clipka wrote:
>> Am 16.03.2015 um 19:01 schrieb Leroy:
>>
>>>> Making the preview exactly reflect the output image in every respect
>>>> would be excessively difficult. (As an extreme example, reproducing
>>>> jpeg artifacts according to the quality settings chosen would require
>>>> to actually generate the jpeg image and then convert it back.
>>>> Obviously that can only happen once the image is completely rendered.
>>>> The same goes for some dithering options at low bit depths.)
>>>
>>>> For consistency, it
>>>> is therefore the current policy to always preview the render at
>>>> maximum quality regardless of the output file format and quality
>>>> parameters.
>>> So does that means the display option +Dxy have deprecated functions
>>> too?
>>
>> Um... actually, no: In the Windows version they don't have any functions
>> at all :P (Don't know about Unix off the top of my hat, but there it
>> either does something non-deprecated, or nothing at all either.)
>>
>> Those options certainly date back to the DOS versions (or even earlier).
>>
> 
> as far as i can tell the video_mode and palette options have no effect
> and produce no warning etc, so they've been removed:
> 
>
http://wiki.povray.org/content/Reference:Display_Output_Options#Display_Hardware_Settings
> 
Correct. They were options for the old X11 API/toolkit, something that
is taken care of by the SDL API (Not that Scene Description Language)
itself now.


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From: Kenneth
Subject: Re: Grayscale_Output=3Dyes doesn't work
Date: 17 Mar 2015 18:40:00
Message: <web.5508a96db912e944f644696d0@news.povray.org>
Leroy <lrw### [at] joplincom> wrote:

> I haven't try to output to a file (there's no point if you can't display
> it).
> Any Ideals?

There actually *is* a goofy way to get a grayscale 'preview' (well, not exactly
a true preview): by RE-rendering your color image in POV-Ray, using a
function_image trick. It will reproduce the image 1:1 in grayscale, quickly.

The idea is to have the following code in a separate SDL scene file, then run it
after your original color render. (Your original image needs to be put into a
folder whose 'path' POV-Ray can recognize, of course.)

If the original image is a .png file, I'm not sure what the assumed-gamma value
should be, in global_settings (I haven't tested that). Probably 1.0.

-------

camera {
  perspective
  location  <0, 0, -1.000>
  look_at   <0, 0,  0>
  right     x*image_width/image_height
  // angle 67 // by default
}

#declare my_function =
function{pigment{image_map{bmp "my color image.bmp"}}} // your original
// color image's name and file type here

box{<0,0,0>,<1,1,0>
 texture {
     pigment{
       image_map{
          function 600,450{ // pixel resolution of original color image
              my_function(x,y,z).gray
                          }
                }
    // These two additions are because function-image results are
    // normally mirror-flipped...
          scale <1,-1,0>
          translate 1*y
            }
  finish{
   ambient 1
   diffuse 0
        }
  }
 translate <-.5,-.5,0>
 scale <4/3,1,1> // scale x to the original color image aspect
// ratio (or alternately, pixel dimension in x divided by pixel dimension
// in y -- 600/450, for example)

 }


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