title: Automated optimization of JPEG 2000 encoder options based on model observer performance for detecting variable signals in X-ray coronary angiograms.
abstract: Image compression is indispensable in medical applications where inherently large volumes of digitized images are presented. JPEG 2000 has recently been proposed as a new image compression standard. The present recommendations on the choice of JPEG 2000 encoder options were based on nontask-based metrics of image quality applied to nonmedical images. We used the performance of a model observer [non-prewhitening matched filter with an eye filter (NPWE)] in a visual detection task of varying signals [signal known exactly but variable (SKEV)] in X-ray coronary angiograms to optimize JPEG 2000 encoder options through a genetic algorithm procedure. We also obtained the performance of other model observers (Hotelling, Laguerre-Gauss Hotelling, channelized-Hotelling) and human observers to evaluate the validity of the NPWE optimized JPEG 2000 encoder settings. Compared to the default JPEG 2000 encoder settings, the NPWE-optimized encoder settings improved the detection performance of humans and the other three model observers for an SKEV task. In addition, the performance also was improved for a more clinically realistic task where the signal varied from image to image but was not known a priori to observers [signal known statistically (SKS)]. The highest performance improvement for humans was at a high compression ratio (e.g., 30:1) which resulted in approximately a 75% improvement for both the SKEV and SKS tasks.
authors.affiliation: Department of Psychology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA. zhang@psych.ucsb.edu
authors.forename: Yani
authors.initials: Y
authors.lastname: Zhang
authors.forename: Binh T
authors.initials: BT
authors.lastname: Pham
authors.forename: Miguel P
authors.initials: MP
authors.lastname: Eckstein
mesh_terms: D000465:Algorithms; D019985:Benchmarking / Q000379:methods; D003196:Computer Graphics / Q000592:standards*; D017023:Coronary Angiography / Q000379:methods* / Q000592:standards*; D044962:Data Compression / Q000379:methods* / Q000592:standards*; D005103:Expert Systems; D006801:Humans; D019146:Hypermedia / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D015588:Observer Variation; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014481:United States