1. A method comprising: decoding a codeword, by a decoder, to recover a pixel value of a pixel of a Doppler enhanced grayscale image, and a flag associated with the pixel, wherein a Doppler enhanced grayscale image comprises grayscale pixels and Doppler enhancement pixels, and wherein a Doppler enhanced grayscale image is captured as a color image; determining, by the decoder, whether the pixel is a grayscale pixel or a Doppler enhancement pixel, using the flag; and outputting, by the decoder, a grayscale pixel or a Doppler enhancement pixel, based on a result of said determining.