Measuring Image Quality of ENT Chip-on-tip Endoscopes

Geleijnse, Gijs; Hakkesteegt, Marieke M.; Groot, Jan de; Metselaar, R M

doi:10.2352/j.imagingsci.technol.2021.65.2.020503

Cited by 3 publications

(8 citation statements)

References 15 publications

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“…2 ). 16 The manufacturers of the ENT-endoscopes specify an operating range of 5 to 50 mm, but the focal length is undisclosed. The tip of the endoscope was positioned at a distance of 30 mm to the target, because ENT-professionals estimated this as the common operational distance.…”

Section: Methodsmentioning

confidence: 99%

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

Geleijnse

Rieger

2022

J. Biomed. Opt.

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. Significance Flexible endoscopes are essential for medical internal examinations. Digital endoscopes are connected to a video processor that can apply various operations to enhance the image. One of those operations is edge enhancement, which has a major impact on the perceived image quality by medical professionals. However, the specific methods and parameters of this operation are undisclosed and the arbitrary units to express the level of edge enhancement differ per video processor. Aim Objectively quantify the level of edge enhancement from the recorded images alone, and measure the effect on sharpness and noise. Approach Edge enhancement was studied in four types of flexible digital ear nose and throat endoscopes. Measurements were performed using slanted edges and gray patches. The level of edge enhancement was determined by subtracting the step response of an image without edge enhancement from images with selected settings of edge enhancement and measuring the resulting peak-to-peak differences. These values were then normalized by the step size. Sharpness was characterized by observing the normalized modulation transfer function (MTF) and computing the spatial frequency at 50% MTF. The noise was measured on the gray patches and computed as a weighted sum of variances from the luminance and two chrominance channels of the pixel values. Results The measured levels were consistent with the level set via the user interface on the video processor and varied typically from 0 to 1.3. Both sharpness and noise increase with larger levels of edge enhancement with factors of 3 and 4 respectively. Conclusions The presented method overcomes the issue of vendors expressing the level of edge enhancement each differently in arbitrary units. This allows us to compare the effects, and we can start exploring the relationship with the subjectively perceived image quality by medical professionals to find substantiated optimal settings.

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Section: Methodsmentioning

confidence: 99%

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

Geleijnse

Rieger

2022

J. Biomed. Opt.

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“…Sharpness was measured using the slanted edge method, the default standard and is described in detail in ISO 12233 [15,17]. This method measures the modulation transfer function (MTF), which is a measure of how well a system can transfer contrast at a certain spatial frequency, i.e., resolution.…”

Section: Objective Image Quality Assessmentmentioning

confidence: 99%

“…These circles served as reference for determining the regions of interest within the image on the test chart. The sharpness was quantified by the frequency (line pairs per mm) at which the MTF first has a value of 50% (MTF50) [15].…”

Section: Objective Image Quality Assessmentmentioning

confidence: 99%

“…Singular studies have objectively measured aspects of image quality of flexible endoscopes [11][12][13][14], but a consistent approach is missing. Camera manufacturers have developed and continuously improved standards that can be adopted and adapted to objectively measure aspects of image quality of endoscopes [15,16]. The Rez Checker Target Nano Matte (Figure 1) is a test chart that was designed by Image Science associates to be more suited to narrow illumination geometries, notably those used in endoscopic imaging.…”

Section: Introductionmentioning

confidence: 99%

“…It supports the objective measurement of the image quality metrics, including sharpness, noise and color fidelity. In our earlier study, we showed that these methods can be applied to different digital ENT endoscopes and yield measurement results that are objective, reproducible and specific per type of endoscope [15].…”

Section: Introductionmentioning

confidence: 99%

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

Geleijnse¹,

Veder²,

Hakkesteegt³

et al. 2022

jist

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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 E 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.

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Edge Enhancement Optimization in Flexible Endoscopic Images to the Perception of Ear, Nose and Throat Professionals

Geleijnse,

Veder,

Hakkesteegt

et al. 2023

The Laryngoscope

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ObjectivesDigital endoscopes are connected to a video processor that applies various operations to process the image. One of those operations is edge enhancement that sharpens the image. The purpose of this study was to (1) quantify the level of edge enhancement, (2) measure the effect on sharpness and image noise, and (3) study the influence of edge enhancement on image quality perceived by ENT professionals.MethodsThree digital flexible endoscopic systems were included. The level of edge enhancement and the influence on sharpness and noise were measured in vitro, while systematically varying the levels of edge enhancement. In vivo images were captured at identical levels of one healthy larynx. Each series of in vivo images was presented to 39 ENT professionals according to a forced pairwise comparison test, to select the image with the best image quality for diagnostic purposes. The numbers of votes were converted to a psychometric scale of just noticeable differences (JND) according to the Thurstone V model.ResultsThe maximum level of edge enhancement varied per endoscopic system and ranged from 0.8 to 1.2. Edge enhancement increased sharpness and noise. Images with edge enhancement were unanimously preferred to images without edge enhancement. The quality difference with respect to zero edge enhancement reaches an optimum at levels between 0.7 and 0.9.ConclusionEdge enhancement has a major impact on sharpness, noise, and the resulting perceived image quality. We conclude that ENT professionals benefit from this video processing and should verify if their equipment is optimally configured.Level of EvidenceN/A Laryngoscope, 2023

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Measuring Image Quality of ENT Chip-on-tip Endoscopes

Cited by 3 publications

References 15 publications

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

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

Edge Enhancement Optimization in Flexible Endoscopic Images to the Perception of Ear, Nose and Throat Professionals

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Measuring Image Quality of ENT Chip-on-tip Endoscopes

Cited by 3 publications

References 15 publications

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

Influence of edge enhancement applied in endoscopic systems on sharpness and noise

The Objective Measurement and Subjective Perception of Flexible ENT Endoscopes&#x2019; Image Quality

Edge Enhancement Optimization in Flexible Endoscopic Images to the Perception of Ear, Nose and Throat Professionals

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