Effect of image compression of direct digital lateral cephalograms on the identifi cation of cephalometric points

Background: With increase of digital imaging, the need for storage space and transmission speed also increases. Compressed images need less storage space and decrease the transmission time. However, compression could compromise image quality. The aim of this study was to evaluate the infl uence of image compression on the identifi cation of cephalometric points on direct digital lateral cephalogram images, compared with the digital imaging and communications in medicine (DICOM) format. Materials and Methods: In this analytical-descriptive study, 19 direct digital lateral cephalograms saved in DICOM format were used. They were converted to joint photographic experts group (JPEG) 2000 format with quality factors 85, 75, and 60 adding up to 76 images (DICOM, JPEG 85, 75, and 60). The images were randomized and eight cephalometric points were identifi ed on each image by a professional, using the x-y coordinate system. Analysis of variance (ANOVA) was applied to investigate if there was a statistically signifi cant difference in the location of cephalometric points between each group of images. All tests were applied at a signifi cance level of 5%. Results: The results did not demonstrate any statistically signifi cant difference in the identifi cation of the eight cephalometric points between the DICOM images and the JPEG2000 quality factors 85, 75, and 60. Conclusion: JPEG2000 images of lateral cephalograms with quality factors 85, 75, and 60 did not demonstrate any alterations in the identifi cation of cephalometric points compared with the DICOM format. JPEG2000 is a reliable fi le format for the compression of digital lateral cephalograms.