A method and apparatus for expanding bit resolution using local information of an image receives an input image. First, second and third threshold value used to enhance bit resolution, to detect a texture and to detect a pattern, respectively, are determined considering global information of the input image. A texture existing in a mask region composed of surrounding pixels within a predetermined range around a current pixel is determined using the second threshold value. A regularly repeated pattern existing in the mask region is determined using the third threshold value if no texture exists in the mask region. The first threshold value is decreased if a texture or pattern exists in the mask region. Values of mask region pixels are adjusted depending on the first threshold value, and bit resolution of the current pixel value is enhanced using a resultant value obtained by filtering the adjusted pixel values.