A method for sharpening gastrointestinal (GI) images and an apparatus thereof are disclosed. A first target distance between a first target region in a regular image and an imaging apparatus is determined, and a second target distance between a second target region in the regular image and the imaging apparatus is determined. One or more first filter parameters for a first de-blurring filter and one or more second filter parameters for a second de-blurring filter are selected from stored filter parameters according to the first and second target distances respectively. A first processed target region is generated by applying the first de-blurring filter to the first target region to improve sharpness of the first target region. A second processed target region is generated by applying the second de-blurring filter to the second target region to improve sharpness of the second target region.