1. An image reading apparatus, comprising: a reading unit; at least one processor; and a memory, wherein the reading unit includes: a first line sensor including a plurality of light receiving elements which are arranged along a first direction and which include light receiving elements receiving light of a first color and light receiving elements receiving light of a second color different from the first color, and a second line sensor including a plurality of light receiving elements which are arranged along the first direction and which include light receiving elements receiving light of the first color and light receiving elements receiving light of the second color, wherein the reading unit is configured to read an image of a target object at a reading position and to generate read data representing the image read by the respective line sensors, wherein the first line sensor and the second line sensor are arranged along a second direction orthogonal to the first direction, and wherein the memory stores instructions which, when executed by the at least one processor, cause the at least one processor to function as: an abnormal pixel detector configured to detect (i) a first abnormal pixel included in the read data read by the reading unit when the target object does not exist at the reading position, based on pixel data from the first and second line sensors and (ii) a second abnormal pixel included in the read data read by the reading unit when the target object exists at the reading position, based on pixel data from the first and second line sensors, and a combining unit configured to generate at least one of (i) first abnormal pixel information obtained by combining results of detecting the first abnormal pixels and (ii) second abnormal pixel information obtained by combining results of detecting the second abnormal pixels.