title: Technical Note: Gray tracking in medical color displays-A report of Task Group 196.
abstract: OBJECTIVE
  The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor.
  
  
  METHODS
  The authors present data regarding the capability of color measurement instruments with respect to their abilities to measure a target white point corresponding to the CIE Standard Illuminant D65 at different luminance values within the grayscale palette of a medical display. The authors then discuss evidence of significant differences in performance among color measurement instruments currently available for medical physicists to perform calibrations and image quality checks for the consistent representation of color in medical displays. In addition, the authors introduce two metrics for quantifying grayscale chromaticity consistency of gray tracking.
  
  
  RESULTS
  The authors' findings show that there is an order of magnitude difference in the accuracy of field and reference instruments. The gray tracking metrics quantify how close the grayscale chromaticity is to the chromaticity of the full white point (equal amounts of red, green, and blue at maximum level) or to consecutive levels (equal values for red, green, and blue), with a lower value representing an improved grayscale tracking performance. An illustrative example of how to calculate and report the gray tracking performance according to the Task Group definitions is provided.
  
  
  CONCLUSIONS
  The authors' proposed methodology for characterizing the grayscale degradation in chromaticity for color monitors that can be used to establish standards and procedures aiding in the quality control testing of color displays and color measurement instrumentation.
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland 20993.
authors.forename: Aldo
authors.initials: A
authors.lastname: Badano
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland 20993.
authors.forename: Joel
authors.initials: J
authors.lastname: Wang
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
authors.forename: Paul
authors.initials: P
authors.lastname: Boynton
authors.affiliation: Polytech Nantes/Université de Nantes, Nantes 44306, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Le Callet
authors.affiliation: Division of Imaging, Diagnostics and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland 20993.
authors.forename: Wei-Chung
authors.initials: WC
authors.lastname: Cheng
authors.affiliation: Barco Kortrijk 8500, Belgium.
authors.forename: Danny
authors.initials: D
authors.lastname: Deroo
authors.affiliation: Henry Ford Health System, Detroit, Michigan 48202.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Flynn
authors.affiliation: Emergo, Tokyo 162-0841, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsui
authors.affiliation: National Institute of Standards and Technology, Boulder, Colorado 80309.
authors.forename: John
authors.initials: J
authors.lastname: Penczek
authors.affiliation: FFEI Limited, Hemel Hempstead, HP2 7DF, United Kingdom.
authors.forename: Craig
authors.initials: C
authors.lastname: Revie
authors.affiliation: Department of Biomedical Engineering, Duke University, Raleigh, North Carolina 90281.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
authors.affiliation: Independent consultant.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Steven
authors.affiliation: NEC Display Solutions, Itasca, Illinois 60143.
authors.forename: Stan
authors.initials: S
authors.lastname: Swiderski
authors.affiliation: Barco Kortrijk 8500, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: Van Hoey
authors.affiliation: Tokyo Institute of Technology, Meguro-ku Tokyo 152-8552, Japan.
authors.forename: Matsuhiro
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: JVCKENWOOD Corporation, Kanagawa, 221-0022, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Hasegawa
authors.affiliation: University of São Paulo, 05508030, Sao Paulo, Brazil.
authors.forename: Balázs Vince
authors.initials: BV
authors.lastname: Nagy
mesh_terms: D000465:Algorithms; D003116:Color; D003201:Computers; D003626:Data Display; D003952:Diagnostic Imaging / Q000191:economics / Q000295:instrumentation* / Q000379:methods*