1. A method of encoding image data, the method comprising: spatially predicting pixel values of a one-dimensional block of an image using blocks spatially adjacent to the one-dimensional block or temporally predicting the pixel values of the one-dimensional block using a temporally previous frame; transforming and quantizing the pixel values of the one-dimensional block; and generating bit streams for a one-dimensional conversion block when the transformed and quantized one-dimensional block is defined as the one-dimensional conversion block.