1. A method of correcting a defective pixel of a digital image, comprising: pre-correcting the defective pixel; calculating similarities between a plurality of normal pixels and the defective pixel; calculating weights of the plurality of normal pixels to the defective pixel based on the similarities between the plurality of normal pixel and the defective pixel; and normalizing the weights and adopting a weighted sum of values of the normal pixels according to the normalized weights as a corrected value of the defective pixel, wherein the calculating similarities between the plurality of normal pixels and the defective pixel comprises: calculating the similarities between the normal pixels and the defective pixel based on a neighborhood similarity by the following equation: 
 D ( P i ,P j )=∥ U R ( P i )− U R ( P j )∥, where Pi represents the defective pixel; Pj represents a normal pixel neighboring the defective pixel Pi; and D(Pi, Pj) is a distance representing a similarity between the pixels Pi and Pj, where the greater the distance is, the lower the similarity becomes, and the lower the weight becomes; U R (Pi) represents a neighborhood of the defective pixel Pi, which is a matrix having a size of 2R+1 centered on the defective pixel P i ; and U R (P j ) represents a neighborhood of the normal pixel P j , which is a matrix having a size of 2R+1 centered on the normal pixel P j .