In article <4007feb8$1@news.povray.org>,
 "Tom Melly" <tom### [at] tomandlucouk> wrote:

> Hmm, does this mean if I reduce the green by that factor in PSP, and then
> grayscale, I'll also have a workable grayscale img? Tests....  Hmm, hard to 
> test (PSP+TOM limitation).

No, this will not work. The values for each channel are stored as 8-bit 
integers, with a minimum of 0 and a max of 255. If you divide the green 
channel by 255 and then try to save the results to the file, you just 
essentially destroyed the green channel...pixels that were 255 will now 
be 1, and all other pixels will be 0.


> However, splitting the image into 3 separate images (one for red, one 
> for blue, etc.), gives me a usable red image (once grayscaled and 
> then .gray in POV). 

This is just truncating the HF data to 8 bits. In decimal, the analogy 
would be dividing it into 10000 levels, then only keeping the first two 
digits...1100, 1200, etc. You lose all the levels in between: 5123 
becomes 5100, 3999 becomes 3900, though it's really a hair away from 
4000.


> The green channel just has some bumps on it which add little to the 
> image, and are pretty irrelvant when using it in an iso (since I want 
> to control my own fine detail). I suspect that the green channel is 
> used to store the "last applied action", which would make 
> single-level undo's easy (which is the only level of undo that 
> leveller supports iirc, which makes sense). Thanks, once again.

No. The green channel stores the lower bits of the 16 bit value. The red 
channel splits the height field into 256 levels, the green channel 
splits each level into 256 more. You want the full 16 bits, *especially* 
with isosurfaces. Dropping the green channel will cause stairstepping or 
terracing artifacts.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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