Diatom autofocusing in brightfield microscopy: a comparative study

Pech-Pacheco, Jose Luis; Cristóbal, Gabriel; Chamorro-Martı́nez, J.; Fernández-Valdivia, J. J.

doi:10.1109/icpr.2000.903548

Cited by 328 publications

(209 citation statements)

References 8 publications

(7 reference statements)

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“…The rationale behind the selected features is to provide a complementary set of image indicators although other alternative traits are possible. The variance of the Laplacian was found particularly effective as a simple and straightforward autofocus metric [15] which can be implemented in a real-time system [29].…”

Section: Image Feature Characterizationmentioning

confidence: 99%

“…and the range filter provide good estimates for the contrast; the variance of the Laplacian as a measure of sharpness; the Angle Measure Technique spectrum (AMT) as a measure of texture complexity and the Anisotropic Quality Index (AQI) as a quality measure provided by an ideal observer [13,[15][16][17]. The rationale behind the selected features is to provide a complementary set of image indicators although other alternative traits are possible.…”

Section: Image Feature Characterizationmentioning

confidence: 99%

“…The variance of a second derivative operator such as the Laplacian was considered as an image sharpness measure [15]. It is given by…”

Section: Image Feature Characterizationmentioning

confidence: 99%

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Oblique illumination in microscopy: A quantitative evaluation

Sánchez¹,

Cristóbal²,

Bueno

et al. 2018

Micron

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Many biological objects are barely distinguished with the brightfield microscope because they appear transparent, translucent and colourless. One simple way to make such specimens visible without compromising contrast and resolution is by controlling the amount and the directionality of the illumination light. Oblique illumination is an old technique described by many scientists and microscopists that however has been largely neglected in favour of other alternative methods. Oblique lighting is created by illuminating the sample by only a portion of the light coming from the condenser. If properly used it can improve the resolution and contrast of transparent specimens such as diatoms. In this paper a quantitative evaluation of OL in brigthfield microscopy is presented. Several feature descriptors were selected for characterising contrast and sharpness showing that in general OL provides better performance for distinguishing minute details compared to other lighting modalities. Oblique lighting is capable to produce directionally shadowed differential contrast images allowing to observe phase details in a similar way to differential contrast images (DIC) but at lower cost. The main advantage of OL is that the resolution of the light microscope can be increased by effectively doubling the angular aperture. OL appears as a cost-effective technique both for the amateur and professional scientist that can be used as a replacement of DIC or phase contrast when resources are scarce.

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Section: Image Feature Characterizationmentioning

confidence: 99%

Section: Image Feature Characterizationmentioning

confidence: 99%

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Oblique illumination in microscopy: A quantitative evaluation

Sánchez¹,

Cristóbal²,

Bueno

et al. 2018

Micron

View full text Add to dashboard Cite

show abstract

“…In this paper, two assessment parameters (Tenengrad function [30] and mean gray value) are introduced to describe real-time image quality, that is, when both of these assessment parameters vary drastically (e.g. | | 10% change rate  ) between the current moment and the last updating moment for real-time monitoring, the dictionary and blur kernel will be updated for image restoration.…”

Section: Image Deconvolutionmentioning

confidence: 99%

Sparsity-based image monitoring of crystal size distribution during crystallization

Liu

Huo

Cai

et al. 2017

Journal of Crystal Growth

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Abstract:To facilitate monitoring crystal size distribution (CSD) during a crystallization process by using an in-situ imaging system, a sparsity-based image analysis method is proposed for real-time implementation.To cope with image degradation arising from in-situ measurement subject to particle motion, solution turbulence, and uneven illumination background in the crystallizer, sparse representation of a real-time captured crystal image is developed based on using an in-situ image dictionary established in advance, such that the noise components in the captured image can be efficiently removed. Subsequently, the edges of a crystal shape in a captured image are determined in terms of the salience information defined from the denoised crystal images. These edges are used to derive a blur kernel for reconstruction of a denoised image.A non-blind deconvolution algorithm is given for the real-time reconstruction. Consequently, image segmentation can be easily performed for evaluation of CSD. The crystal image dictionary and blur kernels are timely updated in terms of the imaging conditions to improve the restoration efficiency. An experimental study on the cooling crystallization of -type L-glutamic acid (LGA) is shown to demonstrate the effectiveness and merit of the proposed method.

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“…[4][5][6][7][8][9] An ideal evaluation function should have good performance of single-peak, unbiasedness and higher signal to noise ratio. 10,11 One of the focal plane searching algorithms is the mountain-climb searching (MCS) algorithm for its convenience to implement and easiness to control the amount of calculation.…”

Section: Introductionmentioning

confidence: 99%

A fast auto-focusing method of microscopic imaging based on an improved MCS algorithm

Cao

2015

J. Innov. Opt. Health Sci.

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An improved \three steps" mountain-climb searching (MCS) algorithm is proposed which is applied to auto-focusing for microscopic imaging accurately and e±ciently. By analyzing the performance of several evaluation functions, the variance function and the Brenner function are synthesized as a new evaluation function. In the¯rst step, a self-adaptive step length which is much dependent on the reciprocal of the evaluation function value at the beginning position of climbing is used for approaching the halfway up the mountain roughly. Secondly, a¯xed moderate step length is applied for approaching the mountaintop of the variance function as closer as possible. Finally, ā ne step is employed for reaching the exact mountaintop of the Brenner function. The microscope auto-focusing experiments based on the proposed algorithm for blood smear detection have been carried out comprehensively. The results show that the improved algorithm can not only guarantee the precision to get clear focal images, but also improve the auto-focusing e±ciency.

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Diatom autofocusing in brightfield microscopy: a comparative study

Cited by 328 publications

References 8 publications

Oblique illumination in microscopy: A quantitative evaluation

Oblique illumination in microscopy: A quantitative evaluation

Sparsity-based image monitoring of crystal size distribution during crystallization

A fast auto-focusing method of microscopic imaging based on an improved MCS algorithm

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