20 June 2005
IMAGE PROCESSING
6-23
Detailed
Descriptions
6.5.6 SUMMARY OF IMAGE PROCESSING FUNCTIONS
Shading correction
: Compensates for the possible differences in the amount of
light at the edges and center of a scanned image caused by the scanner lens, or
scatter among pixels of the CCD.
Pre-Filter Background erase:
Attempts to eliminate the heavy background texture
from copies (newspaper print or documents printed on coarse paper). Elements
below the selected threshold level are eliminated.
Pre-Filter Smoothing:
Reproduces halftones while reducing the incidence of
moiré which can occur as a result of compressing and then decompressing the
image.
Main scan magnification:
Adjusts magnification to the desired level by processing
adjusting multiple, adjacent pixels in the direction of main scanning. Adjustment of
magnification in the sub scan direction is done by changing the scanning speed.
Independent dot erase:
Attempts to recognize and eliminate scattered,
independent dots in copies. Processes only pixels of high density and eliminates
those of low density.
Filtering (MTF filter/smoothing):
Performs mainly edge enhancement with the
MTF filter. Performs smoothing only in the Photo mode. The matrix size of the filter
is 9 pixels x 7 lines.
Gamma (
γ
) coefficient:
Controls the image density for images processed with
grayscaling. Copy density adjustment is achieved with special notch
γ
coefficient
conversion. The best
γ
coefficient suited for the selected mode can be stored and
adjusted as needed.
Grayscale processing:
Performs reproduction of grayscales, using mainly error
diffusion. (In the Photo mode, conducts processing with dithering.)
