Radiology, Vol 170, 133-136, Copyright © 1989 by Radiological Society of North America
Image data compression in magnification hand radiographs
JM Bramble, LT Cook, MD Murphey, NL Martin, WH Anderson and KS Hensley
Department of Diagnostic Radiology, University of Kansas Medical Center, Kansas City 66103.
A study was conducted on the use of an irreversible compression technique,
Fourier quantization, to reduce the amount of digital data needed for an
image. The effect of image compression was studied in radiographs obtained
to diagnose subperiosteal bone resorption. Magnification radiographs of 44
hands were digitized to an array size of 4,096 X 4,096 X 12 bits. Selected
subregions containing a single middle phalanx were compressed and
reconstructed. A subset of the resultant 12-bit uncompressed and 8-, 7-,
and 6-bit compressed images were read by four radiologists whose responses
were analyzed with receiver operating characteristic (ROC) techniques.
There were 81 images used in the ROC analysis, of which 48 were normal and
33 showed subperiosteal resorption. No statistically significant loss of
diagnostic quality was detected for 8- or 7-bit compressed images, with
average compression ratios of 16:1 and 28:1, respectively. Diagnostic
quality was lost with 6-bit images, with an average compression ratio of
107:1.
