Correcting Misleading Image Quality Measurements

Koren, Norman L.

doi:10.2352/issn.2470-1173.2020.9.iqsp-242

Cited by 6 publications

(11 citation statements)

References 3 publications

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“…Our results on sharpness are consistent with Koren who reported MTF50 and MTF50P values for images with a known edge enhancement algorithm and parameters. 18 The consistency with the results obtained with a known method and parameters for edge enhancement confirms that the presented method for unknown method and parameters works. The prerequisite for the presented method to work is that there is an option to switch the edge enhancement between different levels.…”

Section: Discussionsupporting

confidence: 77%

“…8(a) ] and is commonly used as a summary metric for the MTF performance. 18 , 19 Sometimes, other metrics are used such as MTF10. MTF10 is the frequency at which the MTF curve crosses 0.1.…”

Section: Methodsmentioning

confidence: 99%

“…This approximates to the Rayleigh criterion for maximal resolution, at which frequency it is just possible to discern two lines. 17 , 18 MTF10 would correlate to counting television lines. However, MTF10 is not robustly to measure since the signal is relatively close to the noise floor and the slope of the MTF curve is small.…”

Section: Methodsmentioning

confidence: 99%

“…A disadvantage of MTF50 is that it is heavily influenced by edge enhancement. MTF50P is the spatial frequency at which the MTF crosses 0.5 of its peak value and is less sensitive to the effect of edge enhancement 18 [ Fig. 8(b) ].…”

Section: Methodsmentioning

confidence: 99%

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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: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

Geleijnse

Rieger

2022

J. Biomed. Opt.

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“…For comparison purposes, spatial frequencies of MTF50P and MTF10P were selected as metrics to summarize the MTF curves. MTF50P describes a spatial frequency where the image contrast drops to 50% of its peak value and it is less sensitive to artificial image sharpening and can provide a more stable indication of the system performance than other similarly used metrics [98]. MTF10P describes a spatial frequency where the image contrast drops to 10% of its peak value and it is considered to correspond to a limiting resolution below which all information can be considered useless.…”

Section: Detail Reproductionmentioning

confidence: 99%

Evaluating the Quality of TLS Point Cloud Colorization

et al. 2020

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Terrestrial laser scanning (TLS) enables the efficient production of high-density colored 3D point clouds of real-world environments. An increasing number of applications from visual and automated interpretation to photorealistic 3D visualizations and experiences rely on accurate and reliable color information. However, insufficient attention has been put into evaluating the colorization quality of the 3D point clouds produced applying TLS. We have developed a method for the evaluation of the point cloud colorization quality of TLS systems with integrated imaging sensors. Our method assesses the capability of several tested systems to reproduce colors and details of a scene by measuring objective image quality metrics from 2D images that were rendered from 3D scanned test charts. The results suggest that the detected problems related to color reproduction (i.e., measured differences in color, white balance, and exposure) could be mitigated in data processing while the issues related to detail reproduction (i.e., measured sharpness and noise) are less in the control of a scanner user. Despite being commendable 3D measuring instruments, improving the colorization tools and workflows, and automated image processing pipelines would potentially increase not only the quality and production efficiency but also the applicability of colored 3D point clouds.

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Use of wire grid polarizers with liquid crystal display for large-volume stereolithography

Rodriguez

Song

Chen

et al. 2022

Additive Manufacturing

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Correcting Misleading Image Quality Measurements

Abstract: Fast track article for IS&T International Symposium on Electronic Imaging 2020: Image Quality and System Performance proceedings.

Cited by 6 publications

References 3 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

Evaluating the Quality of TLS Point Cloud Colorization

Use of wire grid polarizers with liquid crystal display for large-volume stereolithography

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