Median Filtering Frameworks for Reducing Impulse Noise from Grayscale Digital Images: A Literature Survey

Teoh, Sin Hoong; Ibrahim, Haidi

doi:10.7763/ijfcc.2012.v1.87

Cited by 30 publications

(8 citation statements)

References 24 publications

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“…The median filter was used in image processing as a robust filter [ 18 , 19 ] that preserves the edges of an image. It is a nonlinear filter for removing impulsive noise, and replaces the value of one pixel a ( i , j ) with the median value of all pixels in its neighbourhood: where represent the intensity values in the neighbourhood of the reference pixel, arranged in either increasing or decreasing order.…”

Section: Methods Of Orthodontic Data Processingmentioning

confidence: 99%

Separation of overlapping dental arch objects using digital records of illuminated plaster casts

et al. 2015

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BackgroundPlaster casts of individual patients are important for orthodontic specialists during the treatment process and their analysis is still a standard diagnostical tool. But the growing capabilities of information technology enable their replacement by digital models obtained by complex scanning systems.MethodThis paper presents the possibility of using a digital camera as a simple instrument to obtain the set of digital images for analysis and evaluation of the treatment using appropriate mathematical tools of image processing. The methods studied in this paper include the segmentation of overlapping dental bodies and the use of different illumination sources to increase the reliability of the separation process. The circular Hough transform, region growing with multiple seed points, and the convex hull detection method are applied to the segmentation of orthodontic plaster cast images to identify dental arch objects and their sizes.ResultsThe proposed algorithm presents the methodology of improving the accuracy of segmentation of dental arch components using combined illumination sources. Dental arch parameters and distances between the canines and premolars for different segmentation methods were used as a measure to compare the results obtained.Conclusion A new method of segmentation of overlapping dental arch components using digital records of illuminated plaster casts provides information with the precision required for orthodontic treatment. The distance between corresponding teeth was evaluated with a mean error of 1.38% and the Dice similarity coefficient of the evaluated dental bodies boundaries reached 0.9436 with a false positive rate and false negative rate .

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Section: Methods Of Orthodontic Data Processingmentioning

confidence: 99%

Separation of overlapping dental arch objects using digital records of illuminated plaster casts

et al. 2015

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“…The second step is defect measurement to obtain subsurface information of ROI including defect depth (d), the shortest distance from the boundary of the defect to the inspecting point (D dis ), and thermal wave reflection coefficient of the defect (R), which are achieved by the NLSF method. The third step is noise reduction to enhance image quality (R image and d image), which is achieved by the application of a Median Filter [35] in this paper. The fourth step is to establish the relationship model between h, R, and D dis , shown in Eq.…”

Section: Inspection Processmentioning

confidence: 99%

Three-dimensional subsurface defect shape reconstruction and visualisation by pulsed thermography

Sirikham

Zhao

Liu

et al. 2020

Infrared Physics & Technology

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Defects detected by most thermographic inspection are represented in the form of 2D image, which might limit the understanding of where the defects initiate and how they grow over time. This paper introduces a novel technique to rapidly estimate the defect depth and thickness simultaneously based on one single-side inspection. For the first time, defects are reconstructed and visualised in the form of a 3D image using cost-effective and rapid pulsed thermography technology. The feasibility and effectiveness of the proposed solution is demonstrated through inspecting a composite specimen and a steel specimen with semi-closed airgaps. For the composite specimen, this technique can deliver comparatively low averaged percentage error of the estimated total 3D defect volume of less than 10%.

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“…spatial and/or spectral median based filters. 9 Used on a 3-D HI it may compromise some of the spectral and/or spatial data. In a HI the impulse noise can be observed as stripes in the scanning direction, y, after the dark-frame subtraction.…”

Section: ( )mentioning

confidence: 99%

Increased sensitivity in near infrared hyperspectral imaging by enhanced background noise subtraction

Mehl

Wyller

Burud

et al. 2019

J. Spectral Imaging

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Near infrared hyperspectral photoluminescence imaging of crystalline silicon wafers can reveal new knowledge on the spatial distribution and the spectral response of radiative recombination active defects in the material. The hyperspectral camera applied for this imaging technique is subject to background shot noise as well as to oscillating background noise caused by temperature fluctuations in the camera chip. Standard background noise subtraction methods do not compensate for this oscillation. Many of the defects in silicon wafers lead to photoluminescence emissions with intensities that are one order of magnitude lower than the oscillation in the background noise level. These weak signals are therefore not detected. In this work, we demonstrate an enhanced background noise subtraction scheme that accounts for temporal oscillations as well as spatial differences in the background noise. The enhanced scheme drastically increases the sensitivity of the camera and hence allows for detection of weaker signals. Thus, it may be useful to implement the method in all hyperspectral imaging applications studying weak signals.

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Median Filtering Frameworks for Reducing Impulse Noise from Grayscale Digital Images: A Literature Survey

Cited by 30 publications

References 24 publications

Separation of overlapping dental arch objects using digital records of illuminated plaster casts

Separation of overlapping dental arch objects using digital records of illuminated plaster casts

Three-dimensional subsurface defect shape reconstruction and visualisation by pulsed thermography

Increased sensitivity in near infrared hyperspectral imaging by enhanced background noise subtraction

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