1. An image processing apparatus comprising: a region segmentation unit configured to perform region segmentation processing which extracts black pixel connected regions from a document image; a selection unit configured to select a processing target region from the regions extracted by the region segmentation unit; an internal region combining unit configured to extract internal regions from the processing target regions, and configured to generate a combined internal region by combining the internal regions which are included in the processing target region selected by the selection unit and satisfy a predetermined condition, wherein the internal regions are white pixel connected regions; a table region determination unit configured to determine whether a region obtained based on the combined internal region generated by the internal region combining unit is a table region; and an extraction unit configured to extract the region determined by the table region determination unit as a table region.