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Allegato alla nota 82 del 19990102

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2.1.1 2D-Dithering

For a 2D-Dithering I used Floyd Steinberg
Dithering, but it is possible to make some experiments with Ordered Dithering
or similar method. Floyd-Steinberg Dithering and 3D-Dithering have one
important feature: precious error distribution.

If original voxel intensity is *I(x,y)* and dithered
voxel intensity of the same voxel is *I*_{d}(x,y)
, we can defined, that

ERROR = *I(x,y) - I*_{d}(x,y).

On the image is the one possibility of distribution of
this error information.
Error diffusion in Floyd-Steinberg Dithering
This possibility of error diffusion we can describe via
this equations:

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2.1.2 2D-UnDithering

2D-Undithering is inverse process for Dithering. This Process
we can implement using convolution [2], [3].

*A* is convolutory matrix with
size *(m,n)*. But almost *m* and *n* are odd integers. Undithered
intensity I_{ud}(x, y)
we can describe from dithered intensity I(x, y) as:
Matrix *A* is an normal convolutory matrix. With
good result I used these matrixes: