Error Resilience and Error Concealment in SPIHT 指導教授：楊士萱報告者：鄭博峰日期：四月二十四日

Outline ► Multi-description in SPIHT ► Simulation ► Error Concealment ► Conclusion

Wavelet coder SPIHT Image Error resilience Channel SPIHT Decoder Wavelet Decoder Image Source coder Structure Error concealment

Multi-description in SPIHT ► We assumed that our network situation is packet loss. And this will cause serious degradation in SPIHT. ► After doing by Wavelet transform, almost energy will gather in low frequency. So we must protect the subband with low frequency. ► My method is using MDC to overcome this problem.

MDC ► My method is copying low frequency coefficients to adjacent coefficients. By doing this if the packet loss attack the SPIHT, we can use these copy coefficients to recovery lost coefficient. ► So we must transmit redundancy bits to achieve this method.

Simulation Result

loss one packet loss one packet

Loss two packets

2015/7/1511 Error Concealment method We use linear prediction to do recovery. We use linear prediction to do recovery. So we want to minimum the mean square error.After min mean square error we can get So we want to minimum the mean square error.After min mean square error we can get So So When we doing this,we should think of pixels position. In wavelet transform,pixels which have the same position have a great correlative. So when we doing interpolation we should discuss this. When we doing this,we should think of pixels position. In wavelet transform,pixels which have the same position have a great correlative. So when we doing interpolation we should discuss this.

2015/7/1512 C11 C12 C13 C14 C15 C16 C17 C18 C21 C22 C23 C24 C25 C26 C27 C28 C31 C32 C33 C34 C35 C36 C37 C38 C 41 C42 C43 C44 C45 C46 C47 C48 C51 C52 C53 C54 C55 C56 C57 C58 C61 C62 C63 C64 C65 C66 C67 C68 C71 C72 C73 C74 C75 C76 C77 C78 C81 C82 C83 C84 C85 C86 C87 C88

2015/7/1513 C11 C12 C13 C14 C15 C16 C17 C18 C21 C22 C23 C24 C25 C26 C27 C28 C31 C32 C33 C34 C35 C36 C37 C38 C41 C42 C43 C44 C45 C46 C47 C48 C51 C52 C53 C54 C55 C56 C57 C58 C61 C62 C63 C64 C65 C66 C67 C68 C71 C72 C73 C74 C75 C76 C77 C78 C81 C82 C83 C84 C85 C86 C87 C88

► But this has default. Because by this recovery method, we can only predict the coefficient ’ s magnitude, but we can ’ t correctly predict it ’ s sign. ► In order to overcome this shortcoming, we have to transmit redundancy bits to indict the coefficient ’ s sign.

Future Work ► In my recovery method,I will try use inter- subband ( HL LH HH and LL) and intra- subband. ► In our MDC method, it seems that we can reduce redundancy bits to achieve the same result.