Improving Image Transmission by Using Polar Codes and Successive Cancellation List Decoding

This paper investigates the transmission of grey scale images encoded with polar codes and de-coded with successive cancellation list (SCL) decoders in the presence of additive white Gaussian noise. Po-lar codes seem a natural choice for this application be-cause of their error-correction efficiency combined with fast decoding. Computer simulations are carried out for evaluating the influence of different code block lengths in the quality of the decoded images. At the encoder a default polar code construction is used in combination with binary phase shift keying modulation. The results are compared with those obtained by using the clas-sic successive cancellation (SC) decoding introduced by Arikan. The quality of the reconstructed images is assessed by using peak signal to noise ratio (PSNR) and the structural similarity (SSIM) index. Curves of PSNR and SSIM versus code block length are presented il-lustrating the improvement in performance of SCL in comparison with SC.</p

A Novel Real-time and Progressive Secret Image Sharing with Flexible Shadows Based on Compressive Sensing

[[abstract]]A novel real-time and progressive secret image sharing scheme with flexible-size shadows is proposed. First, a secret image is measured by compressed sensing (CS). Then, the quantized measurement values are divided into n shadows using Shamir's (t,n)-threshold scheme. At the receiver side, the secret image can be reconstructed if any t of n shadows are obtained, but fewer than t shadows reveal no information. Due to the fact that CS's reconstruction quality is flexibly adaptive to the number of measurements, our scheme features flexible shadow size and obtains the property of real-time and progressive transmission as well as error resilient. Experimental results show that the proposed scheme achieves better performance in view of the reconstructed secret image