Epson ES-1000C Reference Manual page 115

Dropout colors (monochrome reading only)
The dropout color is the color that is treated as white, and is not read
during the scanning operation. On a color scanner a dropout color can
be chosen from among green, red, or blue. Dropout color can be used
to avoid reading a certain color of the document. For example,
corrections written in red on a draft can be erased by specifying the
red dropout color.
The settings of 10 , 20 , and 30 should be used only to intentionally
H H H
specify a dropout color. To change from color scanning to
monochrome without choosing a dropout color, use the value 00 .
H
When a dropout color is selected, the color attributes in the status byte
indicate the selected primary color. The image data of a dropout color
can also be used as the color image data of one of the separated colors.
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Command Reference