Unequal Error Protection for Radiography Image Transmission Using Protograph Double LDPC Codes

In this paper, a novel unequal error protection (UEP) scheme, which is constructed from protograph double low-density parity-check (PD-LDPC) codes, and tailored for medical images is proposed to minimize the end to end image distortion over additive white Gaussian noise (AWGN) channel. The UEP scheme is carried out by adopting different coding strategies in terms of the different significant levels and different entropies of image data streams from discrete cosine transform (DCT). A typical radiography image and other two gray-scale images are exploited in the simulation. The experimental results show that the proposed scheme can evidently increase the peak signal to noise ratio (PSNR) value of the received images and reconstruct the transmitted images with good quality even at a very low signal-to-noise ratio (SNR). In particular, the proposed scheme outperforms the other UEP schemes based on regular D-LDPC codes and turbo codes by up to 0.5 and 2.5 dB in the SNR when the PSNR of the reconstructed images reach the expected upper bound, respectively.