This page illustrates a direct comparison between JPEG and JPEG2000.  The comparison is made at 5 different compression ratios, ranging from 20:1 to 100:1. The user can select the compression ratio by clicking on the buttons below the images. The PSNR shown is the average PSNR of the three color channels.

Notice that the JPEG2000 compressed image is consistently 3-5 dB better than the JPEG image. Visually, the difference is most obvious at the high compression ratios where JPEG introduces severe blocking artifacts.

To see the same comparison on a different image, click on one of the thumbnails below: