Image reading apparatus, multifunction printer apparatus, and image processing method

An image reading apparatus which reads an image original by irradiating the image original with light from a light emitting unit for emitting beams of three primary colors, respectively, and by receiving reflected light of the light by a light receiving unit, comprising:

• a designation unit configured to designate an image reading operation mode;
• a setting unit configured to set a condition used to perform image reading in accordance with the operation mode designated by said designation unit;
• a reading unit configured to perform, under the condition set by said setting unit, at least either of image reading complying with a primary color reading method of irradiating the image original sequentially with beams of the three primary colors by the light emitting unit and reading the beams reflected by the image original by the light receiving unit, and image reading complying with a complementary color reading method of irradiating the image original simultaneously with beams of two primary colors in each of three different combinations of the three primary colors by the light emitting unit and reading the beams reflected by the image original by the light receiving unit;
• and
• a control unit configured to control said reading unit so as to, in a case where the image reading for the image original is performed twice by said reading unit, switch over from one of the primary color reading method and the complementary color reading method used in first image reading to the other of the primary color reading method and the complementary color reading method used in second image reading.