Rate-distortion unequal error protection for fractal image codes

Fractal image codes are very sensitive to bit errors because the decoding of a block is dependent not only on the code information associated to this block but also on the code information associated to other blocks. We analyze the sensitivity of a fractal code to transmission errors in a binary symmetric channel. We provide two rate-distortion unequal error protection techniques that allocate the code bits to protection classes in a nearly optimal way. We give an implementation for BCH and RCPC channel codes and show that RCPC codes are preferable. For a binary symmetric channel bit error probability of 0.1 and a total code rate of 0.5 bpp, the loss in reconstruction quality with our best implementation was about 3.38 dB for the 512 x 512 Lenna image, yielding a PSNR of 27.12 dB.