Provided is an image reading apparatus including an imaging unit that images light incident from a medium on which an image is formed, a measurement unit that measures a color value on an image, based on image data obtained by the imaging unit, in correspondence with a position on the image, a generation unit that generates error information indicating an error included in the color value according to the color value measured by the measurement unit and a relative position of the position on the image with respect to an optical axis of the imaging unit, and an output unit that outputs the error information generated by the generation unit and the measured color value.