1. A method of localizing an object part in a digital image by utilizing one or more processors, said method comprising: accessing digital image data containing an object part; obtaining an initial position estimate which is a region that estimates a location of said object part; extracting, using at least one processor, a sub-image window which is larger than said initial position estimate and which surrounds said initial position estimate of said object part location; calculating feature values based on pixel values within said sub-image window to estimate a displacement of said object part relative to said initial position estimate; determining an updated position estimate for said object part location based on said calculated feature values; extracting another sub-image window which is larger than said updated position estimate and which surrounds said updated position estimate of said object part location; and determining whether said updated position estimate is a final position estimate for said object part based on feature values calculated for said another sub-image window.