On Wed, 26 Apr 2000 14:44:46 -0500, Chris Huff
<chr### [at] yahoocom> wrote:

>What is that supposed to do, other than just lightening or (with 
>negative values) darkening the image? Maybe I misunderstood you...but it 
>sounds like adding in a gray "pixel" with an intensity equal to the 
>levelling value.

Glad you implemented it. Its purpose is to control contrast while the
divisor is used to control brightness (generally speaking). It is
expecially useful if the divisor differs from the sum of the cells of
the convolution matrix. For example this:

<0,1,0,
 1,5,1,
 0,1,0>

will make a slight blur with a divisor of 9. If you lower the divisor,
the image gets brighter. Adding an offset of about 0.8 puts the
brightness back to about where it was but with a much increased
contrast. It works in the reverse direction, too, with a higher
divisor and negative offset.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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