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24 February, 1999
IMAGE PROCESSING
ACS (Auto Color Selection)
A259D511.WMF
Auto color selection mode determines if an original is black/white or color. Then
black copy mode or full color mode is automatically selected to match the original.
To recognize if the original has a color area or not, the RGB video signals are
compared. If the maximum difference among RGB signal levels (MAX-MIN in the
above diagram) is within a certain range, the pixel is considered black and white.
During the 1st scanning cycle, the latent image is developed with the amount of
black toner specified by the gamma (γ) corrected RGB video signals. If the original
does not have any color areas, the 2nd scanning is aborted and the developed
image is transferred from the transfer belt to the copy paper. Then the black and
white copy comes out. If the original has a color area, copying resumes in the full
color copy mode (4 scans).
Users can maximize the quality of their output by selecting priority for Bk or full
color original in ACS mode, using a User Tool (the default is Bk). The Bk setting
prevents the UCR process from reducing the image density too much in low image
density photo areas. This is explained in more detail in the section on UCR.
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