Ricoh B039 Service Manual page 216

IMAGE PROCESSING
Scanner Gamma ( γ) γ) γ) γ) Correction
The CCD output is not proportional to the quantity of light received. Scanner γ
correction corrects the CCD output so that grayscale data is proportional to the
quantity of light received.
The machine has two possible scanner gamma curves: Text and Photo. As the
default setting, Text is used in all modes (SP4-922). When selecting Text, the
machine does not use scanner γ correction. As a result, the output is darker than
the image density on the original. The advantage of this is that the machine can
bring out lower density black areas. The disadvantage is that the machine cannot
bring out gradations in darker areas, i.e. differences in shades of dark colors are
hard to distinguish.
When selecting Photo, the machine uses scanner γ correction. One advantage of
this is that the machine can bring out gradations in dark areas of photo image
originals. The disadvantage is that it in some cases images come out lighter than
the customer desires.
Text
Output
Photo
Original Density
B039D008.WMF
SM 6-23 B039/B040/B043