On 10/09/2017 16:23, clipka wrote:
> Am 10.09.2017 um 15:55 schrieb Stephen:
>> A while ago when I was working with df3s. Both Alain and Clipka
>> mentioned that df3s use grey levels not three channels of colour.
>> Tga2df3.exe creates RGB df3s (The utility Oosawa 4D Volume Viewer, can
>> split them using only one of the channels).
>> How does PovRay's internal workings handle this, mathematically?
>> If PovRay reads a value of (say) <0.5, 0.7, 0.1> what density value
>> would it give it?
>> Similarly for <0, 0.9, 0> or any other combination of colour components?
> 
> To the best of my knowledge, there is no such thing as a RGB DF3, so
> you're asking the wrong question.
> 

Knowing that you are asking the wrong question is always good.


> The right questions should be, "how does tga2df3.exe handle RGB colours
> mathematically?" and "how does OOsawa 4D Volume Viewer get colours out
> of it?"
> 
> I would presume tga2df3.exe uses the greyscale value (or an average of
> the channels) from the images; and that OOsawa 4D Volume Viewer
> essentially just uses a colour_map-ish system to convert density to colour.
> 

I'm not convinced. I distinctly remember Oosawa telling me that the 
opened df3 was not monochromatic and asking me which colour channel to 
use. I say remember because I had an unfortunate accident with my PC and 
lost all the data on it and my backups did not work. <insert obscenity 
here> And when I downloaded the current version. That did not happen. 
When I looked at a newly created df3 by tga2df3 in a hex editor it was 
95% nulls.
So I will just grumble to myself. :-(


-- 

Regards
     Stephen

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