1. An image processing apparatus comprising: an obtaining unit configured to obtain an image, the obtaining unit comprising an imaging unit configured to set an imaging condition of the image; a generating unit configured to generate a plurality of feature maps for a plurality of features of the image, wherein each of the feature maps corresponds to one of the features of the image; an imaging situation determining unit configured to determine the imaging condition set by the imaging unit; a weighting factor storage unit configured to store weighting factors for the feature maps and imaging conditions therein such that the weighting factors and the imaging conditions are associated with each other; a weighting unit configured to read weighting factors that are associated with the imaging condition determined by the imaging situation determining unit, and to weight the feature maps using the read weighting factors; and a detector configured to detect a region of interest from the image based on feature distributions of the weighted feature maps.