An efficient autofocus algorithm for a visible microscope on a Mars lander

Lüthi, Benjamin; Thomas, N.; Hviid, S. F.; Rueffer, P.

doi:10.1016/j.pss.2010.05.002

Cited by 9 publications

(6 citation statements)

References 6 publications

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“…In addition, in order to analyze and view the results more conveniently and intuitively, this study normalizes all the results, as shown in Figure 5 . The non-subsampled contourlet transform (NSCT), Tenengrad algorithm [ 29 ], Roberts algorithm [ 30 , 31 ], discrete cosine transform (DCT) [ 32 , 33 ], energy of gradient (EOG) [ 34 ] algorithm, Canny algorithm [ 35 , 36 ], and Laplacian algorithm [ 37 , 38 ] are selected for this comparative experiment. The Tenengrad algorithm uses a Sobel [ 39 , 40 ] operator to extract gradient values in horizontal and vertical directions, and then calculates the gradient square sum of all pixels.…”

Section: Resultsmentioning

confidence: 99%

A Method for Medical Microscopic Images’ Sharpness Evaluation Based on NSST and Variance by Combining Time and Frequency Domains

Zhou

et al. 2022

Sensors

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An algorithm for a sharpness evaluation of microscopic images based on non-subsampled shearlet wave transform (NSST) and variance is proposed in the present study for the purpose of improving the noise immunity and accuracy of a microscope’s image autofocus. First, images are decomposed with the NSST algorithm; then, the decomposed sub-band images are subjected to variance to obtain the energy of the sub-band coefficients; and finally, the evaluation value is obtained from the ratio of the energy of the high- and low-frequency sub-band coefficients. The experimental results show that the proposed algorithm delivers better noise immunity performance than other methods reviewed by this study while maintaining high sensitivity.

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Section: Resultsmentioning

confidence: 99%

A Method for Medical Microscopic Images’ Sharpness Evaluation Based on NSST and Variance by Combining Time and Frequency Domains

Zhou

et al. 2022

Sensors

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“…Focusing was performed by translating the specimen along its axis in increments of the depth of field (40 μm). Algorithms for analyzing the successive focal planes have been developed [54]. The resolution was approximately 4 μm/pixel.…”

Section: Microscopes Used On Planetary Missionsmentioning

confidence: 99%

Imaging technologies and strategies for detection of extant extraterrestrial microorganisms

Nadeau

Bedrossian

Lindensmith

2018

Advances in Physics: X

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There is no reductionist definition of life, so the way organisms look, behave, and move is the most definitive way to identify extraterrestrial life. Life elsewhere in the Solar System is likely to be microbial, but no microscope capable of imaging prokaryotic life has ever flown on a lander mission to a habitable planet. Nonetheless, high-resolution microscopes have been developed that are appropriate for planetary exploration. Traditional light microscopy, interferometric microscopy, light-field microscopy, scanning probe microscopy, and electron microscopy are all possible techniques for the detection of extant micro-organisms on Mars and the moons of Jupiter and Saturn. This article begins with a general discussion of the challenges involved in searching for prokaryotic life, then reviews instruments that have flown, that have been selected for flight but not flown or not flown yet, and developing techniques of great promise for life detection that have not yet been selected for flight.

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“…The entire microscope was mechanically translated along its axis in increments of the depth of field in order to focus; in-focus elements were then combined into an image. Improved algorithms for such image processing have since been developed (Luethi et al , 2010 ). The resolution was approximately 4 μm pixel −1 .…”

Section: Instrument Conceptsmentioning

confidence: 99%

Microbial Morphology and Motility as Biosignatures for Outer Planet Missions

et al. 2016

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Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement—Biosignatures—Microbiology—Europa—Ice. Astrobiology 16, 755–774.

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An efficient autofocus algorithm for a visible microscope on a Mars lander

Cited by 9 publications

References 6 publications

A Method for Medical Microscopic Images’ Sharpness Evaluation Based on NSST and Variance by Combining Time and Frequency Domains

A Method for Medical Microscopic Images’ Sharpness Evaluation Based on NSST and Variance by Combining Time and Frequency Domains

Imaging technologies and strategies for detection of extant extraterrestrial microorganisms

Microbial Morphology and Motility as Biosignatures for Outer Planet Missions

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