A conveying device can selectively execute discharge processes of a plurality of discharge procedures each having a different mode of discharge to a discharge tray. An image reading portion reads images on document sheets conveyed along a conveyance path and outputs data about read images. An image reading control method includes detecting a target image that satisfies a predetermined sorting condition associated with any one of the plurality of discharge procedures from the read images. The image reading control method further includes, in a case where the target image is detected, executing a discharge control that causes the conveying device to execute the discharge process of the discharge procedure corresponding to the target image.