Effects of Image Compression on Linear Measurements of Digital Panoramic Radiographs

Abstract

This study aimed to evaluate the accuracy of panoramic radiographs obtained by digital system based on charge coupled device (CCD) and a phosphor storage plate (PSP) system with two different file formats, JPEG irreversible type and BMP. Linear measurements of artificial bony defects were made in dry mandibles with a digital caliper. Measures of digital panoramic radiographs were taken in ImageJ(r) software. Each measurement was performed twice by an experienced examiner. The intra-rater agreement was considered very strong (Pearson's correlation coefficient of 0.97). There was no significant difference between the linear measurements of dry mandibles, considered the gold standard, in relation to measurements obtained from digital radiographs (p=0.47). The error of these measures for the CCD was 1.04 mm (9.97%) for JPEG images and 1.03 mm (9.99%) for those with BMP format. For the PSP images, these values were 1.48 mm (14.94%) and 1.43 mm (14.43%), respectively. Although there was no statistical difference between the images with JPEG and BMP format, for both digital systems (p=1.00 for CCD and p=0.98 for PSP system), errors made on radiographs obtained by PSP system were significantly higher than those of CCD (p<0.05). The size of the files saved in JPEG was also significantly lower (p=0.005) compared with the files saved in BMP. It may be concluded that the digital radiographs, both saved in JPEG and BMP formats, are accurate, regardless the used digital system, and JPEG images are more suitable for teleradiology.

Effect of decompression and online transmission on the dimensional changes of .stl files generated by intra-oral scanning

“…This characteristic may be a limitation in its use, since it generates the need for a large amount of free space for storage in computers, servers, and difficulties in the process of online transmission [ 4 ]. To favor this process, data compression can be considered as a strategy to reduce storage space and improve data transfer rates [ 10 , 11 ]. Thus, this study aimed to evaluate the influence of compression and online transmission of images in STL format obtained by intraoral scanners.…”

“…compression can be considered as a strategy to reduce storage space and improve data transfer rates [10,11]. Thus, this study aimed to evaluate the influence of compression and online transmission of images in STL format obtained by intraoral scanners.…”