An image scanning apparatus includes a scanner which scans a document and generates a scan image, a sensor which senses vertical streaks, a detector which detects a contents area on the scan image, and a corrector which corrects the vertical streaks on the scan image while protecting the contents area. The sensor may sense pole points in a main scan direction on the scan image, sense vertical streak suspected pixels based on a brightness difference and/or a color difference between the sensed pole points and surrounding pixels of the pole points, and may further sense vertical streaks based on the consecutiveness of the vertical streak suspected pixels toward a sub scan direction.