An image processing system capable of preventing resubmission of a scanned image from being required due to an undesired object which obstructs visibility. The image processing system includes a scanned image generation unit configured to read an original and generate a scanned image of the read original, and submits an image to a management server. A continuous pixel area which includes a plurality of pixels whose pixel values are higher than a predetermined density threshold value and has an area size equal to or larger than a predetermined value is identified from a scanned image. Whether or not the identified continuous pixel area is an area of an undesired object which obstructs visibility is determined. A continuous pixel area determined as the area of an undesired object is notified to a user before the scanned image is submitted to the management server.