Toshiba e-studio 167 - 2-in-1; 4-in-1 Copying

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Shading correction
A variation is caused by the following factors in the CCD output.
1) The light source has a variation in its light distribution.
2) Each of the 7,084 elements varies in optoelectronic conversion efficiency.
These differences need to be corrected and this correction is referred to as a shading correction. The
shading correction is performed by applying a normalization process using the following formula on the
black data and the white data obtained in advance to correct the lighting variance and element variation
of the image data.
(S-K)
(W-K)
I = k x
k: Coefficient
S: Image data before correction
K: Black data (stored in "Black" memory)
W: White data (stored in "White" memory)