title: Effect of image compression of direct digital lateral cephalograms on the identification of cephalometric points.
abstract: 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 influence of image compression on the identification of cephalometric points on direct digital lateral cephalogram images, compared with the digital imaging and communications in medicine (DICOM) format.
  
  
  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 identified 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 significant difference in the location of cephalometric points between each group of images. All tests were applied at a significance level of 5%.
  
  
  RESULTS
  The results did not demonstrate any statistically significant difference in the identification of the eight cephalometric points between the DICOM images and the JPEG2000 quality factors 85, 75, and 60.
  
  
  CONCLUSIONS
  JPEG2000 images of lateral cephalograms with quality factors 85, 75, and 60 did not demonstrate any alterations in the identification of cephalometric points compared with the DICOM format. JPEG2000 is a reliable file format for the compression of digital lateral cephalograms.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental School, Khorasgan (Isfahan) branch, Islamic Azad University, Isfahan, Iran.
authors.forename: Sima
authors.initials: S
authors.lastname: Saghaie
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental School, Khorasgan (Isfahan) branch, Islamic Azad University, Isfahan, Iran.
authors.forename: Roshanak
authors.initials: R
authors.lastname: Ghaffari
keywords: Cephalometry; data compression; dental; digital; radiographs