Abstract: In order to decrease the complexity of the traditional algorithm for ROI coding,a new algorithm based on rate pre-allocation is proposed.The code block of ROI is primarily encoded,and its coding stream length is controlled to implement from lossy to lossless ROI coding.Certain bytes are allocated to each block of background regions(BG) according to their entropy value.In the light of the allocated rate,T1 coding process on the block of BG can be real-time terminated.As a result,the whole coding process is simplified.The experimental results show that the proposed scheme can efficiently reduce the cost of computation and memory usage compared with the bit-plane lifting and rate-distortion slope lifting ROI coding methods,which is suitable for implementation in hardware.