1. A method for eliminating defective pixels and noise in an image sensor, comprising: extracting each pixel value of an image using a color filter; calculating a mean value of the extracted image; estimating a noise variance, estimating a first threshold for determining whether a pixel is defective, and estimating a second threshold for calculating a weight value for a pixel, from the mean value; determining whether each pixel is defective; calculating a weight value for the each pixel and calculating a weighted signal mean and a weighted signal variance of each pixel; and eliminating noise from the image using the noise variance, the weighted signal mean, and the weighted signal variance.