| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 100 === Huge media data are generated in our daily life, and the demand on the quality of media data is also getting increased. Thus, the processing, transmission as well as the storage of media data is getting important nowadays. For this, a JPEG2000 (Joint Photographic Experts Group 2000) coding standard is published in the year of 2000 for the lossy and lossless compression of still images. The JPEG2000, which applies the use of the wavelet transformation and provides progressive transmission, is a high-performance image compression standard. However, when the bit stream of the coded image is transmitted over the network, bit errors can occur due to limited bandwidth or interferences. Under this condition, an error concealment mechanism should be necessary for the receiver so that the image quality can be maintained. For this, we proposed in this paper an error concealment mechanism by using a Median Edge Detector (MED) as well as a Least squares (LS)-based predictor for the reconstruction of lost JPEG2000 data bits. Experimental results show that a very good quality for the reconstructed image can be achieved by using the proposed MED-based error concealment mechanism with a very slight computational cost. In addition to the MED-based error concealment mechanism, we also test the proposed LS-based approach on different test images. Though with a higher computational complexity, the experimental results show that the proposed LS-based approach can have a very good quality for reconstructed images in the lower frequency band.
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