As shear-warp volume rendering is the fastest rendering method, image quality is not good as that of other high-quality rendering methods. In this paper, we propose two methods to improve the image quality of shear-warp volume rendering. First, the supersampling is performed in an intermediate image space. Then is proposed an efficient method to transform between the volume and the image coordinates at the arbitrary ratio. Second, the preintegrated rendering technique is utilized for shear-warp rendering. To do this, a new data structure called overlapped min-max block is used. Using this structure, the empty space leaping can be performed so the rendering speed is maintained even though when the pre-integrated rendering is applied. Consequently, shear-warp rendering can generate on high-quality images comparable to those generated by the ray-casting without degrading the speed.