> From: jam### [at] dh70qdu-netcom (Jamie Davison)
> Newsgroups: povray.general
> Date: Sat, 8 Jul 2000 15:35:19 +0100
> Subject: Re: Smoothing 8 bit greyscale images
> 
> On Sat, 08 Jul 2000 14:23:06 +0200, Thorsten Froehlich wrote...
>>> Is there a standard method for 'upsampling' 8 bit greyscale images to 16 bit
>>> using MacMegaPov?  I know that POV can read 8 bits and write 16 but without
>>> an imtermediate smoothing step the resultant image isn't any smoother.
>> 
>> A computer screen can only display 8 bits per colour component, which also
>> limits it to 256 (8 bit) levels of grey.  You will not be able to see the
>> difference on screen if you use 65536 (16 bit) levels of grey.
>> 
>> 16 bit per colour component or 16 bit greyscale for output are only useful
>> if you plan to post process the image in a program like PhotoShop, i.e. in
>> order to print it.
> 
> 16bit grayscales could be useful for Heightfields, I suppose...
> 
> And I suppose that using interpolate 2 or 4 on an image mapped surface
> could get you some more colour depth, but usually it just blurs the
> detail in the image.
> 
> Bye for now,
> Jamie.
>

Hello again,

Thanks for the useful information.  However, perhaps my initial post wasn't
very clear.  I'm particularly interesed in image maps being used to modulate
isosurfaces.  So far my attempts have been pretty rough looking. I'm
assuming the roughness is a result of using 8 bit grey scale images.  The
Pov documentaion is pretty specific about the inherent value of 16 bit grey
scale with regard to heightfields.  It seems to me that if a user could
'upsample' and blur the 8 bit images, the resultant 16 bit would be a lot
smoother when applied to an isosurface.  I can't believe the power and
elegance of the isosurface patch.  Even a simple gradient image when applied
spherically of cylindrically to an appropriate isosurface results in
fabulous deformation.  If I can just 'smooth' those images....

Thanks a zillion,

Glenn

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