1. An image processing apparatus, comprising: a feature acquiring device, configured to acquire values of a plurality of features of each pixel block in an object region of an image frame, each pixel block containing N×M pixels, N≧1, M≧1; an estimating device, configured to estimate capability, of each of the plurality of features of each pixel block, of reflecting difference between background and an object in the image frame according to the object region and the background in the image frame; and a feature weighting device, configured to weight the plurality of features of each pixel block according to the capability of each feature reflecting difference between background and the object.