1. An image processing apparatus comprising: an acquisition unit configured to acquire a document image; a primary region segmentation unit configured to segment the acquired document image into a plurality of regions; a detection unit configured to detect a text region including an erroneous sentence from the regions segmented by the primary region segmentation unit; a secondary region segmentation unit configured to detect a second attribute region partly overlapped with an original sentence of the erroneous sentence, and separate the detected region into the second attribute region and a part of the original sentence; and a combining unit configured to combine the part of the original sentence separated by the secondary region segmentation unit with the text region including the erroneous sentence.