The deterioration of read-image quality caused by LED color-tone variations is
suppressed in a case in which a white-color LED illumination module is used as
a light source of a color-image reading apparatus. The color-image reading apparatus
includes an illumination module formed of a plurality of white-color LEDs arranged
in a main-scanning direction; an image sensor such as a CCD; a unit for moving
the original and the image sensor relatively in a sub-scanning direction; and an
input masking unit. The illumination module is formed of LEDs having the same color-tone
rank. The color-image reading apparatus also includes a setting unit for setting
a color-tone rank for the illumination module, and a control unit, such as a CPU,
for switching a parameter of the input masking unit according to the color-tone rank.
