Ricoh VT3500, Руководство по обслуживанию

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Consider a small black point on a original as shown in the illustration (a) and
(b). The 6-bit image data (range 0 to 63) for this section of the original is
shown in (c). If the the threshold level is 32, all the pixels in this area will
becomes single-bit white data and the image will not be reproduced (d).
The MTF correction prevents this image loss this way:
The value of the target pixel is multiplied by 3. Then, 3/8 of the values of the
pixels to the left and right, 1/8 of the values of the pixels two steps to the left
and right, and 1/2 of the values of the pixels above and below are subtracted
from the new value of the target pixel. (If the result is less than zero, then the
pixel datum is set to zero.)
After the MTF correction is applied, the image data of the example is as
shown in (e) and (f) above. The small black point is reproduced on the print.
0 0 0 0
30
0 12 4 0
0 12 0
0 0 0 0
0 0 0 0
(a) Section of document
(b) Enlarged view of dot
(c) Image data after
A/D conversion
(d) Print without MTF correction
(threshold level: 32)
–1/2
–3/8
–1/2
–1/8 –1/8 –3/8 3 X
0 0 0
63
0
19.5 1.5
0
22.7
0
0 0
0 0 0
0
0
0
0
0
(e) Image data after
MTF correction
(f) Print after MTF correction
1 December 1993
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