A New Scheme to Improve the Quality of Compressed Image Transmission by Turbo Unequal Error Protection Codes

A novel Turbo Unequal Error Protection (UEP) coding scheme is proposed in this paper. In our scheme, two error protection levels of Turbo codes are achieved by a new rate-compatible puncturing mechanism. When coding with the Turbo UEP encoder, both of the two parity bits are reserved for the high error protection bits, and for the low error protection bits, most bits hold one parity bit, while in order to obtain a 1/2 coding rate, some bits are selected randomly and have no parity bit. So this UEP scheme has an unchanged coding rate and realizes the UEP capability in one coding process. Then we apply this Turbo UEP code to the transmission of the DCT compressed images. The DCT coefficients those are more sensitive to channel noise are provided high error protection level, and the remaining coefficients are provided low error protection level. By this means, the quality of the image transmission is improved and there is no additional bit rate or coding delay due to the UEP capability.