Shogo Tokurei RT, Presenter: Nothing to Disclose

Junji Morishita PhD, Abstract Co-Author: Research Grant, Eizo Nanao Corporation

Masaki Asahara MS, Abstract Co-Author: Nothing to Disclose

Fukai Toyofuku PhD, Abstract Co-Author: Nothing to Disclose

The color and monochrome LCDs could be evaluated consistently with various cameras by compensating for spectral sensitivities of cameras based on the luminance. This method can be applied to the evaluation of image quality, quality control, and quality assurance of LCDs in radiology department.

Recently, color liquid-crystal displays (LCDs) as well as monochrome LCDs have increasingly been utilized for displaying medical images. Color LCDs are composed of red (R), green (G), and blue (B) sub-pixels. Image quality of LCDs based on two-dimensional (2-D) luminance distributions cannot be evaluated by using a telescopic-type luminance meter. The purpose of this study is to develop a consistent method for evaluating color and monochrome LCDs based on luminance by use of commercially available cameras.

Three single-lens reflex digital cameras with different spectral sensitivities were used. Unprocessed RGB signals of cameras depended on the spectral sensitivity of each camera. The RGB signals of cameras were transformed to grayscale signals corresponding to the luminance of LCDs by employing weighting factors for each color to compensate for different spectral sensitivities of cameras. The weighting factors were determined based on the ratio of measured luminance of RGB test patterns displayed on a color LCD. Luminance uniformity, modulation transfer function (MTF), and Wiener spectrum (WS) of LCDs were evaluated based on the 2-D images of the grayscale signal.

The grayscale signals determined from RGB signals of cameras corresponded to the luminance obtained by the luminance meter. Luminance uniformity can be represented by the 2-D images visually and quantitatively. The MTFs and WSs of a color LCD before compensating for spectral sensitivities of cameras were different in the three cameras. On the other hand, the MTFs and WSs of an LCD obtained by use of the compensating method corresponded well for the three cameras. Our proposed method has the potential for evaluating the 2-D luminance distributions of LCDs consistently in different cameras with various spectral sensitivities.

Tokurei, S, Morishita, J, Asahara, M, Toyofuku, F, Development of a Consistent Method for Evaluating Color and Monochrome Displays Based on Luminance by Using Commercially Available Cameras.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12025087.html