The effects of incremental brightness and contrast adjustments on radiographic data: a quantitative study.
OBJECTIVE
To determine the border level of brightness and contrast changes in order to prevent the loss of originality of the quantitative data on digital dental radiographs.


METHODS
After measuring the baseline mean grey values (MGVs) of a fixed region of interest on the alveolar bone and an aluminium step wedge, incremental brightness and contrast adjustments were performed on a digital periapical radiograph. The distribution of the data was analysed to investigate the significance of the changes on radiodensitometric data after incremental increase of brightness and contrast.


RESULTS
The original MGVs were easily retrieved after brightness adjustments; however, the contrast increase led to more complicated density changes. The originality of the data was saved up to 50 units of contrast increase, but further than this limit, significant radiodensitometric changes occurred.


CONCLUSIONS
Contrast adjustments should be performed cautiously when making quantitative analyses on the digital radiographs.
Güneri
P
P
Ege University School of Dentistry, Department of Oral Diagnosis and Radiology, Bornova 35100, Izmir, Turkey. peleen_2000@yahoo.com
Lomçali
G
G
Boyacioğlu
H
H
Kendir
S
S
D015502:Absorptiometry, Photon; D000539:Alveolar Process / Q000000981:diagnostic imaging; D003287:Contrast Media; D006801:Humans; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging; D008027:Light; D011856:Radiographic Image Enhancement; D019252:Radiography, Dental, Digital / Q000379:methods* / Q000706:statistics & numerical data*
D003287:Contrast Media