The Objective Measurement and Subjective Perception of Flexible ENT Endoscopes' Image Quality

G. Geleijnse*, L. L. Veder, M. M. Hakkesteegt, R. M. Metselaar

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Web of Science)


ENT-flexible endoscopes are an important tool for ear, nose and throat (ENT) professionals to examine the upper airway. Although image quality has improved significantly in the past decade, there is no generally accepted approach to measure this objectively. Sharpness, visual noise and color fidelity are aspects of image quality that can objectively be measured. The purpose of this study was to explore the relationship between these quality metrics and the subjective perception of image quality by ENT-professionals. The image quality of six different flexible endoscopes was assessed objectively and subjectively. Objective measurements were obtained using the Rez Checker Target Nano Matte and comprised sharpness (MTF50), visual noise and color fidelity (CIE 1E 2000). Subjective image quality ranking was obtained by presenting images of a single larynx to 30 ENT-professionals in a forced pairwise comparison and asking them to select the image with the best image quality. Differences in image quality between endoscopes are reliably detected by objective measurement and subjective assessment. A strong positive correlation was found between sharpness and subjective ranking (p < 0.005). Visual noise and color fidelity may be relevant, but did not correlate with the subjective assessment and were probably overshadowed by the strong correlation between sharpness and subjective ranking in the data. The authors found that number of pixels on screen to display the registered image differs per type of endoscope, however more pixels do not necessarily imply a sharper image. The authors will continue their investigation of image quality metrics and their relation to diagnostic accuracy which can provide feedback on design and manufacturing optimization to the industry.

Original languageEnglish
Article number030508
Number of pages6
JournalJournal of Imaging Science and Technology
Issue number3
Publication statusPublished - May 2022

Bibliographical note

Funding Information:
We would like to thank Jet de Gier and Sahar Mokhles for recording the laryngoscopic images and the ENT-professionals for comparing the image pairs. We also thank EIZO Europe GmbH for loaning the diagnostic monitor and remote support for calibration. We acknowledge Olympus Nederland B.V, PENTAX Nederland B.V. and KARL STORZ Endoscopie Nederland B.V. for their support and loaning endoscopes and video processors. Further support was solely from institutional and/or departmental sources. There are no sources of funding to be acknowledged.

Publisher Copyright:
© Society for Imaging Science and Technology 2022


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