A computer-implemented method of detecting a foreign object on a background object in an image is provided. The computer-implemented method includes extracting image features of the image based on image characteristics of the background object and a suspected foreign object; detecting a salient region in the image based on a human visual attention model; generating a salient region mask based on detection of the salient region; obtaining the image features in a region surrounded by the salient region mask; perforating feature combination and feature vector length normalization on the image features of the region surrounded by the salient region mask to generate normalized feature vectors; and identifying the suspected foreign object using an image classifier, wherein the image classifier uses the normalized feature vectors as input for identifying the suspected foreign object.