1. An image encoding method comprising: detecting a texture region in a current picture; selecting only a portion of the detected texture region as a sample texture for synthesizing the texture region, wherein the sample texture is smaller in size than the detected texture region; and encoding the selected sample texture in place of the detected texture region, wherein the encoding of the selected sample texture comprises encoding position information of the detected texture region and position information of the selected sample texture in the current picture, wherein the encoding the selected sample texture comprises generating a prediction value for the sample texture by performing prediction from a previously encoded reference picture and encoding a residual value that is obtained by subtracting the generated prediction value from the sample texture.