A wavelet to DCT progressive image transcoder
Po-Chin Hu, M. Kavesh, Zhi-Li Zhang · 2002
A transcoder design is proposed in which the transcoder loads the pre-encoded embedded wavelet coefficients and computes the DCT coefficients. The resulting DCT coefficients are quantized and sorted by multi-grid embedded coding to output a compressed DCT bitstream. This transcoder has two operational modes: open-loop and closed-loop. The open-loop scheme is designed for direct transcoding, targeted to applications in which receivers are connected to the transcoder through a fast network and demand the same rate. In contrast, the closed-loop scheme is designed for fully progressive transcoding, targeted to receivers which are connected to the transcoder through a slow network connection, and may demand heterogeneous rates. The performance of the transcoder is evaluated in both open-loop mode and close-loop mode.