In this paper, we propose a novel QoS (Quality of Service) estimation scheme for JPEG 2000 coded image at RTP (realtime transfer protocol) layer without decoding the image. QoS of streaming video is estimated in view of several points, such as, transmission delay, or quality of received images. In this paper, we evaluate the QoS in terms of quality of received images. Generally, RTP is carried on top of UDP, and hence, quality of transmitted images could be degraded due to packet loss. To estimate the quality of received JPEG 2000 coded image without decoding, we use RTP header extension in order to send additional information to the receiver. The effectiveness of the proposed method is confirmed by the computer simulations.