1. An image processing apparatus for real time motion detection comprising: a sub-sampling module that receives and sub-samples a current image and a plurality of previous images; a census transform module that performs census transform on each of the sub-sampled images to obtain a census vector; a correlation calculation module that calculates and compares correlation values between the current image and the plurality of previous images using the census vector and detects a region having highest correlation; and a motion detection module that tracks positions of pixels corresponding to the region having the highest correlation to detect motion information in the images, wherein the sub-sampling module performs sub-sampling using, as a sub-sampling interpolation method, at least one of bilinear interpolation, nearest-neighbor interpolation, and cubic convolution interpolation.