Background Bruising is the most common type of mechanical damage, which is inevitable along the postharvest chain, including harvesting, sorting, packaging and so on. It's the major cause of postharvest loss. However, the detection of bruises mainly relies on manual inspection which is time-consuming and mistake-prone, especially for the early bruises. In recent years, with the development of computer vision, more and more imaging techniques for real-time and automated bruise detection are proposed and studied again. Scope and approach This review provides an overview of recent advances in imaging techniques for bruise detection. The imaging techniques presented include spectral techniques (biospeckle imaging, hyperspectral/multispectral imaging, fluorescence imaging and structured-illumination reflectance imaging), nuclear magnetic techniques (magnetic resonance imaging and X-ray imaging) and thermal imaging. The basic principles of these imaging techniques and their application in bruise detection are concisely introduced. Key findings and conclusion The imaging techniques mentioned above exhibit potential to detect the bruised tissue and the bruise volume in real time and to overcome the fallibility, tediousness, destructiveness, and time-consumption, which are the disadvantages of traditional methods. In future research, integration of these techniques, developing specific algorithms for bruise detection and attempting to apply them into an assembly line for commercial value will be the research hotpots. In addition, the range of applications of these techniques for fruit and vegetable types also needs to be extended, and applying them in a practically assembly line should be enhanced.

Recent advances in imaging techniques for bruise detection in fruits and vegetables

Background Biospeckle laser technique is an emerging non-destructive, quality detection tool used for the evaluation of biological samples. It is rapid, easy to operate and economical, and assures the quality and safety of the fresh produces. Scope and approach The biological activity of the materials is altered due to the contamination, damages, maturation, etc. Hence, these factors can be non-destructively analyzed by the biospeckle method combined with the numerical processing techniques. Several qualitative and quantitative methods namely, Fujii, Absolute Value Difference, Inertia Moment, Generalized Difference, etc have been developed for effective biospeckle analysis. Major applications of this tool include identification of bruises, maturation and ripening changes in fruits and vegetables, meat quality detection, seed viability analysis, and detection of fungal colony infection. Key findings and conclusions Even though the technology has got a wide range of applications, there are some limitations and challenges that hinder its large scale adoption. The impediments such as external noise and interferences have to be addressed to obtain accurate results. There is a need for the development of standardized procedures for conducting the analysis. This review mainly discusses the various applications of biospeckle laser technique as a non-destructive tool in quality and safety analysis, the methods adopted for the evaluation process, the relation between biochemical changes and biospeckle and the various challenges thereof.

Biospeckle laser technique – A novel non-destructive approach for food quality and safety detection

In the present paper intensity-based algorithms have been applied to differentiate the bruised and fresh regions of an Indian apple through biospeckle technique during its 9 day shelf life. Existing algorithms such as the co-occurrence matrix, inertia moment, absolute value difference, generalized difference, parameterized Fujii, biospeckle activity (BA) value, granulometric size distribution (GSD) and grey-level co-occurrence matrix (GLCM), as well as three new proposed algorithms namely parameterized generalized difference, alternative generalized difference (AGD) and parameterized global average Fujii, have been used for qualitative and quantitative analysis. Co-occurrence matrix and activity level spectral maps have been used for qualitative analysis, whereas mean activity plots, curve of the BA index, GSD plots and texture features have been used for quantitative analysis. The experimental results suggest that overall difference in biospeckle activity between the bruised and fresh regions is maximum for the inertia moment method (521.99). Of the three proposed algorithms AGD gives the maximum overall difference in biospeckle activity (42.35). In addition, the BA value and parameters of the GLCM have also been applied for the first time to distinguish between the bruised and fresh regions of an Indian apple, and it is concluded that both the methods may be used for good differentiation between the bruised and fresh regions of apples.

https://iopscience.iop.org/article/10.1088/1054-660X/26/11/115601/pdf

Biospeckle technique for the non-destructive differentiation of bruised and fresh regions of an Indian apple using intensity-based algorithms

The recovery of the topography of eggs using digital images analysis allows the prediction with a non-destructive and with a non-contact way of the egg mass, yolk, egg white, and eggshell, which are products widely used in the industrial sphere. The present research seeks to develop a methodology to recovery the tridimensional shape of eggs through image analysis, in particular by the moire technique with the proposition of an independent calibration. For the accomplishment of this research, eggs of different sizes classified in XL (more than 73g), L (63 to 73g), M (53 to 63 g), and S (until 53 g) were used. In each test realized at the laboratory, one egg, randomly selected was illuminated with the projection of grids and the images were taken and processed to obtain the tridimensional shape of the object by moire technique (TM). The dimensions of its main axes were measured by means of a caliper rule, being used as a reference for the TM calibration. Empirical equations were adjusted for the correction of the dimensions, presenting coefficient of determination of 0.961, 0.955, and 0.988. TM showed to be adequate for recovering the egg topography providing errors smaller or equal to 5.47%, with a clear demand of an independent calibration in the three dimensions, and without any standard object.

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Recuperação da topografia de ovos por meio da técnica de moiré e calibração independente

Application of wood in rural construction is diffused all around the world since remote times. However, its inclusion in structural design deserves strong support from broad knowledge of material properties. The pertinent literature reveals the application of optical methods in determining the complete field displacement on bodies exhibiting regular as well as irregular surfaces. The use of moiré techniques in experimental mechanics consists in analyzing the patterns generated on the body surface before and after deformation. The objective of this research work is to study the qualitative deformation behavior of wooden testing specimens under specific loading situations. The experiment setup follows the literature description of shadow moiré methods. Results indicate strong anisotropy influence of the generated displacement field. Important qualitative as well as quantitative stress and strain distribution were obtained wooden members which are applicable to rural constructions. Keywords—Moiré methods, wooden structural material, rural constructions.

Photomechanical Analysis of Wooden Testing Bodies under Flexural Loadings

El bambu es considerado como una materia prima muy importante para los paises en vias de desarrollo, pues combina levedad con una elevada resistencia mecanica Hasta ahora no se conoce adecuadamente el comportamiento del material cuando es sometido a los ensayos de caracterizacion mecanica En este trabajo se busco evaluar probetas de bambu ( Guadua angustifolia ) sometidas al ensayo de compresion simple Se utilizo la tecnica de  moire  de sombra para mapear las deformaciones de las probetas en funcion de la cantidad de nudos presentes en ella (0, 1 o 2) Los resultados obtenidos evidenciaron la adecuacion de la tecnica utilizada, permitiendo observar la distribucion de las lineas de iso-deformacion en el bambu Palabras clave :  bambu; guadua; moire

https://www.scielo.cl/pdf/maderas/v9n3/art 10.pdf

Técnica de moiré aplicada al análisis de esfuerzos de compresión en el bambú guadua

Biospeckle Supported Fruit Bruise Detection

The dynamic speckle or biospeckle is an interference phenomenon generated at the reflection of a coherent light by an active surface or even by a particulate or living body surface. The above mentioned phenomenon gave scientific support to a method named biospeckle which has been employed to study seed viability, biological activity, tissue senescence, tissue water content, fruit bruising, etc. Since the above mentioned method is not invasive and yields numerical values, it can be considered for possible automation associated to several processes, including selection and sorting. Based on these preliminary considerations, this research work proposed to study the interaction of a laser beam with vegetative samples by measuring the incident light intensity and the transmitted light beam intensity at several vegetative slabs of varying thickness. Tests were carried on fifteen slices of apple tissue divided into three thickness groups, i.e., 4 mm, 5 mm, 18 mm and 22 mm. A diode laser beam of 10mW and 632 nm wavelength and a Samsung digital camera were employed to carry the tests. Outgoing images were analyzed by comparing the gray gradient of a fixed image column of each image to obtain a laser penetration scale into the tissue, according to the slice thickness. Keywords—Fruit, laser, laser transmission, vegetative tissue.

Laser Transmission through Vegetative Material

Atualmente, diversas técnicas de processamento de imagens têm sido empregadas para quantificar o nível de atividade do solo e água por meio do biospeckle laser. Este, por sua vez, é um fenômeno ótico que ocorre quando há incidência de luz coerente em um material biológico que exibe algum tipo de atividade. A sua aplicação na análise do solo é importante na determinação de padrões associados a atividade biológica, assim com base nestas informações é possível determinar a melhor e mais fidedigna frequência que determine os níveis de atividade biológica do solo. O Biospeckle pode futuramente ser usado como ferramenta nas técnicas de nutrição e fenômenos da biota do solo. Diante disso, este trabalho tem por objetivo avaliar o potencial do biospeckle laser e análises com Waveletes no monitoramento dos níveis de atividade biológica em argissolo vermelho amarelo, típico do estado de Sergipe. Pode-se afirmar que a metodologia aplicada para análise é sensível a diferenças da atividade do solo. A identificação das faixas de frequência geradas pela interferência do solo nos níveis de atividades estudados pode ser calculada com base no teorema da amostragem. Os resultados mostraram que pode haver interferência entre a atividade biológica e a atividade de água no solo, uma vez que, no solo não estéril a diferenciação das faixas de frequência por umidade é potencializada.

Estudo da frequência de interação da atividade biologica em solo de tipo argissolo vermelho amarelho pelo método de biospeckle dinâmico

Plant architecture research subjects are of significant importance to genetics, photosynthesis, transpiration, crop-machine mechanical relationship, etc. In this sense, this research work had been carried in developing a new technique to generate the three dimensional view of plant shape. In this work the plant architecture determination will be carried out by means of a phase shift moire method. The importance of the proposed method is based on the application of a sequence of four grids out of phase by an angle of π/2 radians one from each other. A digital camera was employed to capture the moire patterns, which will generate the image to be processed. The procedure of image analysis involved softwares as Microsoft Powerpoint, Coreldraw and Idrisi. The use of a highly continuous sinusoidal grid, of a collimated light beam, of a higher resolution Charge Coupled Device Camera, as well as the superposition of image discontinuities during the unwrapping procedure included in the phase shifting method, avoided noise occurrence satisfactorily, improving image quality.The conception of tests leading to height determination to generate a topographic description of a plant model was conceived based on optical moire techniques. Obtained results reveal a great potential of the proposed method in determining plant architecture with high precision, at low cost and being not time demanding. Keywords: Moire; Interferometry, Plant Architecture.

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Silvestre Rodrigues

Papers

Técnica de moiré aplicada al análisis de esfuerzos de compresión en el bambú guadua

Biospeckle Supported Fruit Bruise Detection

Laser Transmission through Vegetative Material

Estudo da frequência de interação da atividade biologica em solo de tipo argissolo vermelho amarelho pelo método de biospeckle dinâmico

Moiré inteferometry applied to plant architectural studies / moiré interferométrico aplicado ao estudo da arquitetura de plantas