On-axis and off-axis viewing of images on CRT displays and LCDs: Observer performance and vision model predictions

Elizabeth A. Krupinski, Jeffrey Johnson, Hans Roehrig, John Nafziger, Jeffrey Lubin

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Rationale and Objectives. Although cathode-ray tube (CRT) displays typically are used for softcopy display of radiographs in the digital reading environment, liquid crystal displays (LCDs) currently are being used as an alternative. LCDs have many desirable viewing properties compared with a CRT, but significant image degradation can occur with off-axis viewing. This study compares observer performance and predictions from a human visual system model for on-axis and off-axis viewing for CRT displays versus LCDs. Materials and Methods. A set of mammograms with different lesion contrasts (n = 400) were shown to six radiologists on CRT and LCD monitors, once on-axis and once off-axis. Observer performance was measured by using receiver operating characteristic techniques. Performance was correlated with results of a human vision model designed to predict observer performance (just noticeable difference [JND]metrix model). Two approaches were used to generate model metrics; a paired discrimination and channelized model observer approach. Results. The performance of human observers indicated that on-axis viewing with the LCD was better than with the CRT, but off-axis viewing was significantly better with the CRT than LCD (F = 8.8175; P < .0001). The paired discrimination model correctly predicted on-axis, but not off-axis, results. The channelized model observer correctly predicted both on- and off-axis results. Conclusion. Off-axis viewing of radiographic images on an LCD monitor degrades human observer performance significantly compared with a CRT display. Care should be taken in the clinic to avoid off-axis viewing during diagnostic interpretation.

Original languageEnglish (US)
Pages (from-to)957-964
Number of pages8
JournalAcademic radiology
Issue number8
StatePublished - Aug 2005


  • Channelized model observer
  • Digital display
  • Just noticeable difference (JND) metrix
  • Observer performance
  • Off-axis viewing
  • Vision model

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


Dive into the research topics of 'On-axis and off-axis viewing of images on CRT displays and LCDs: Observer performance and vision model predictions'. Together they form a unique fingerprint.

Cite this