A comparison of subjective quality indices between JPEG and JPEG 2000 compressed cephalometric images

The purpose of this study was to compare the effect of application of the JPEG 2000 standard to the previous standard of JPEG (1992) on image quality of digitized cephalometric images under various compression ratios.; Seven digital cephalometric images were enhanced for optimal viewing and compressed with JPEG and JPEG 2000 at three levels of compression. TIFF images were preserved to measure intra-rater reliability. These images were shown to eleven orthodontic residents for assessment. The residents viewed the images and scored sixteen various cephalometric points of interest on a scale of 1-4.; Kappa scores reflected that hard tissue, low contrast points had the least intra-rater reliability, while soft tissue points had the highest concordance. No difference was found in image quality between the original JPEG and the newer wavelet-based JPEG 2000 algorithm. A ratio of 4:1 compression showed no differences from the original TIFF images. Where differences were found, a 4:1 ratio showed superior image quality when compared to 27:1 or 40:1.