An image coding device includes a first block encoder and a second block encoder. The first block encoder compresses input pixel values including first and second input pixel values in a block. The first input pixel value is located at a first position of the block, and the second input pixel value is located at a second position of the block. The second block encoder compresses the input pixel values by the unit block. The first and second block encoders compare the input pixel values based on different methods of compression. The first block encoder outputs the first input pixel value as a first compressed pixel value, and compresses the second input pixel value to a second compressed pixel value.