Hi . . .

Does anyone have any experience with having their ray-traced images printed
commercially?
 I have had a couple of images reproduced as book covers and the colors are not the
same.  I understand that POV uses the RGB system and printing on a press uses CMYK. 
When I convert my POV images to CMYK, they always lose a lot of brilliance and
saturation.

Is there any way to know in the POV program what you are going to get in CMYK before
you trace the final high res?

Thanks.
Michael

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On Fri, 02 Feb 2001 11:50:28 -0700, Michael Z. Tyree wrote:
>Is there any way to know in the POV program what you are going to get in CMYK before
you trace the final high res?

Perhaps not in the POV program, but if you have or have access to Photoshop,
you can convert the gamut to that of your service bureau's imagesetter and
get a good idea.

(Gamut conversion like this would make a good postprocess filter, hint hint.)

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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in <slr### [at] fwicom> Ron Parker wrote:

>(Gamut conversion like this would make a good postprocess filter, hint
>hint.) 
>

Why?

If its for printing, it's the job of the service bureau, they should have 
dedicated professional software for colour separation, gamut conversion 
and matching to the press.


Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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I did it a few times:

1. you need to convert your image from RVB to CMYK ;

2. very often, "they lose a lot of brilliance and saturation": I know this :-(
Only Photoshop (or a similar) can correct this. But it's not easy if you are not
familiar with these softwares.


"Michael Z. Tyree" wrote:

> Hi . . .
>
> Does anyone have any experience with having their ray-traced images printed
commercially?
>  I have had a couple of images reproduced as book covers and the colors are not the
same.  I understand that POV uses the RGB system and printing on a press uses CMYK. 
When I convert my POV images to CMYK, they always lose a lot of brilliance and
saturation.
>
> Is there any way to know in the POV program what you are going to get in CMYK before
you trace the final high res?
>
> Thanks.
> Michael

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On 2 Feb 2001 18:33:25 -0500, ingo wrote:
>in <slr### [at] fwicom> Ron Parker wrote:
>
>>(Gamut conversion like this would make a good postprocess filter, hint
>>hint.) 
>>
>
>Why?

For preview purposes, as stated.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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On 2001-02-03 16:55, Ron Parker <ron### [at] povrayorg> wrote:
>On 2 Feb 2001 18:33:25 -0500, ingo wrote:
>>in <slr### [at] fwicom> Ron Parker wrote:
>>
>>>(Gamut conversion like this would make a good postprocess filter, hint
>>>hint.) 
>>>
>>
>>Why?
>
>For preview purposes, as stated.

Why not perform the RGB->CMYK conversion in a separate program? This
doesn't seem to need any information about the scene, so it doesn't
benefit from being implemented as a postprocess filter. OTOH, it needs
information about the output device, which povray doesn't (and
shouldn't) have (except for gamma correction).
	
	hp

-- 
   _  | Peter J. Holzer    | All Linux applications run on Solaris,
|_|_) | Sysadmin WSR       | which is our implementation of Linux.
| |   | hjp### [at] wsracat      | 
__/   | http://www.hjp.at/ |	-- Scott McNealy, Dec. 2000

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On Sat, 3 Feb 2001 22:44:33 +0100, Peter J. Holzer wrote:
>Why not perform the RGB->CMYK conversion in a separate program? This
>doesn't seem to need any information about the scene, so it doesn't
>benefit from being implemented as a postprocess filter. OTOH, it needs
>information about the output device, which povray doesn't (and
>shouldn't) have (except for gamma correction).

My thought was that it might benefit from having the higher-precision color
information that's available to a postprocess filter, but that might not make
it worthwhile.

But then, it wouldn't be the first postprocess filter that would be better
implemented in a separate program, would it?

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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Ron Parker wrote:

> On Sat, 3 Feb 2001 22:44:33 +0100, Peter J. Holzer wrote:
> >Why not perform the RGB->CMYK conversion in a separate program? This
> >doesn't seem to need any information about the scene, so it doesn't
> >benefit from being implemented as a postprocess filter. OTOH, it needs
> >information about the output device, which povray doesn't (and
> >shouldn't) have (except for gamma correction).
>
> My thought was that it might benefit from having the higher-precision color
> information that's available to a postprocess filter, but that might not make
> it worthwhile.
>

Then output a 16 bit per channel PNG from POV, you should have enough
precision...
Or should we go back to a 'new' format for output picture ?

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