1. An apparatus, comprising: an acquiring unit configured to acquire a read image acquired by reading an original by a reading apparatus; a specifying unit configured to specify, in the read image acquired by the acquiring unit, a line segment having a first characteristic amount which is not less than a first threshold value as a candidate of an edge of the original, the line segment being a part of the read image and the first characteristic amount being a part of a characteristic amount of the read image; a deciding unit configured to decide, in case where the line segment specified by the specifying unit is extended in the read image including the line segment, whether a second characteristic amount of the extended line segment is not less than a second threshold value smaller than the first threshold value, the extended line segment being a part of the read image and the second characteristic amount being a part of a characteristic amount of the read image; and a determining unit configured to determine an area corresponding to the original in the read image, based on the line segment specified by the specifying unit and the extended line segment, in a case where the deciding unit decides that the second characteristic amount is not less than the second threshold value.