Optimization of a contrast-detail-based method for electronic image display quality evaluation

The authors previously reported a general technique based on contrast-detai l methods to provide an overall quantitative evaluation of electronic image display quality. The figure-of-merit reflecting overall display quality is called maximum threshold contrast or MTC. In this work we have optimized t he MTC technique through improvements in both the test images and the figur e-of-merit computation. The test images were altered to match the average l uminance with that observed for clinical computed radiographic images. The figure-of-merit calculation was altered to allow for contrast-detail data w ith slopes not equal to -1. Preliminary experiments also were conducted to demonstrate the response of the MTC measurements to increased noise in the displayed image. MTC measurements were obtained from five observers using t he improved test images displayed with maximum monitor luminance settings o f 30-, 50-, and 70-ft-Lamberts. Similar measurements were obtained from two observers using test images altered by the addition of a low level of imag e noise. The noise-free MTC and MTC difference measurements exhibited stand ard deviations of 0.77 and 1.55, respectively. This indicates good measurem ent precision, comparable or superior to that observed using the earlier MT C technique. No statistically significant image quality differences versus maximum monitor luminance were seen. The noise-added MTC measurements were greater than the noise-free values by an average of 4.08 pixel values, and this difference was statistically significant. This response is qualitative ly correct, and is judged to indicate good sensitivity of the MTC measureme nt to increased noise levels. Copyright (C) 1999 by W.B. Saunders Company.