Transmission of block-based transform coded images over lossy packet networks is subject to packet losses, causing blocks to be lost or damaged. In this paper, we propose a new hybrid error concealment algorithm to achieve continuous QoS in terms of both image quality and reconstruction time. It integrates the dc concealment with the information-restoration scheme, and provides a continuous range of time-quality trade-offs by controlling percentage of the missing blocks to be reconstructed by the dc concealment. Extensive experimental results show that our approach works well for both homogeneous and textured images, and achieves high-quality images in short time.