Multispectral photography using multi-channel led cluster

The results presented of an experiment of multispectral imaging the using led clusters without the use of filters . The advantages and disadvantages of this method relative to conventional survey through the filter system. The sources of random and systematic errors demonstrated. Discusses the prospects of using this method of multispectral imagery in creating instrumentation for printing.Представлены результаты эксперимента по применению светодиодного кластера для мультиспектральной фотосъёмки без использования светофильтров. Рассмотрены преимущества и недостатки данного способа по отношению к традиционной съёмке через систему фильтров. Указаны источники возникновения случайной и систематической погрешностей. Обсуждаются перспективы использования данного способа мультиспектральной съёмки при создании контрольно-измерительной аппаратуры для полиграфии

Improved technology of multispectral imaging with multichannel LED cluster

Неравномерное освещение является одним из основных факторов, ведущих к потереточности восстановления спектрального коэффициента отражения по данным мультиспектральной съёмки. При использовании светодиодов эта проблема усугубляется точечным характером пространственно-разнесённых излучателей. В статье рассматривается улучшения светодиодной мультиспектральной съёмочной установки и процесса обработки полученных изображений. Точность результатов существенно улучшена по сравнению с предшествующими работами.Non-uniformity lighting is one of the main factors leading to the loss reconstruction accuracy of of the spectral reflectance according to multispectral photography. When using LEDs, this problem is ompounded by the spatial-spaced point emitters. The article deals with the improvement of led multispectral imaging stand and processing of the obtained images. The accuracy of the results significantly improved compared to previous works

Compensation of spatial and temporal non uniformity of the pulse illumination in multispectral photography

В статье предлагаются методические улучшения в процесс обработки мультиспектральных изображений, полученных при импульсном освещении. Учитывается влияние как неравномерности освещения, так и нестабильности энергии отдельных импульсов. Уровень «чёрного» определяется по отдельному «чёрному» кадру. Для определения уровня «белого» в исследуемых точках применяется интерполяция вместо фильтрации. Точность восстановления спектрального коэффициента отражения существенно улучшилась по сравнению с рядом предшествующих работ.The article suggests methodological improvements in the processing of multispectral images obtained under pulsed illumination. The effect of non-uniform illumination and the instability of the energy of individual pulses takes into account. The black level is determined by a separate black shot. To determine white level in the examination points, interpolation is applied instead of filtering. The accuracy of the reconstruction of spectral reflectance was significantly improved in comparison with several previous works

Investigation of light source effects on digital camera-based spectral estimation

The influence of light sources on digital camera-based spectral estimation is explored. The CIE daylight and non-CIE daylight illuminants with different Correlated Color Temperature (CCT) are first tested comparatively, results indicate that CCT can be used to describe the performance of the CIE daylight illuminants for spectral estimation but not applicable to all types of light sources. To further investigate the mechanism of light effects on spectral estimation, several handmade special shape of Spectral Power Distribution (SPD) are tested, results show that the red component in visible spectrum is crucial for a higher spectral estimation accuracy. Finally, several feature metrics of SPD are proposed to evaluate the performance of the light sources in spectral estimation, results illustrate that the better the feature metrics the better the spectral estimation accuracy

LED Selection for Spectral (Multispectral) Imaging

Research was performed to design an LED-based spectral imaging system having channels, commonly referred to as a multispectral imaging system. The first part tackled the evaluation of a camera model in predicting the signals of a 10 LED LEDmotive Technologies Spectra Tunelab coupled with a Finger Lakes Instrumentation panchromatic camera. The camera model was shown to be valid and effective in predicting the camera signal taking into account the color transformation noise. The second part involved the computational selection of 10 LEDs in order to determine the optimum combination for a custom Spectra Tunelab. The computational selection used the spectral data provided by the manufacturer for their 37 available LEDs. The LEDs were grouped according to a specified wavelength range. The binning process helped in decreasing the computational cost and time; the possible combinations were reduced to 110,592 from the initial calculated value of 348,330,136 possible combinations. The combinations were further reduced to 1000 according to spectral reflectance Root-Mean-Square-Error (RMSE). The Euclidean and score ranking methods were then used to evaluate color transformation noise, spectral error and colorimetric accuracy. Goodness of Fit Coefficient and Throughput were calculated as well to further evaluate the combinations. A compromise among the values were reached to identify the best possible LED combination. The optimal combination has peak wavelengths at 390 nm, 450 nm, 475 nm, 505 nm, 540 nm, 550 nm, 590 nm, 620 nm, 660 nm, and 745 nm. All the LEDs were narrow band except the LED with its peak wavelength at 550 nm. This particular LED was similar to the human visual system’s luminous efficiency function. Its inclusion was important for colorimetric accuracy and small color transformation noise. When evaluating a large color-gamut target made using commonly used commercial pigments and several artist pigments, the following quality metrics were achieved: average ∆E00 of 0.12, total Noise, N of 3.35, a lightness noise (∆L) of 1.22, spectral reflectance RMSE of 6.4 x10-3, GFC of 0.97 and a total throughput of 646.85

Assessment of the influence of spectral radiation of modern light sources on the observer

Cílem předkládané práce je vytvoření metodiky pro posouzení vlivu spektrálního vyzařování různých moderních světelných zdrojů na pozorovatele. Pozorovatelem v tomto případě může být lidské oko, kamerový systém, rostlina apod. Ve své práci se zabývám především vyhodnocováním vlivu spektrálního vyzařování různých moderních světelných zdrojů na kamerové systémy a lidské oko. Práce je určena pro široký okruh uživatelů, kteří mohou díky této databázi ověřit využitelnost jakýchkoliv světelných zdrojů či kamerových čipů v praxi. Práce se skládá z otevřené databáze, která má všestranné využití. V databázi po nahrání vlastních dat nebo využití již nahraných spektrálních křivek zářivostí světelných zdrojů a spektrálních citlivostí kamerových čipů je možné zobrazit výsledné optimalizované spektrální složení pro zvolenou kombinaci světelný zdroj – světelný senzor. Dále je v databázi možnost vypočítat výslednou hodnotu optimalizovaného poměrného spektrálního složení mezi různými spektrálními křivkami světelných zdrojů s rozdílnou náhradní teplotou chromatičnosti a spektrální citlivosti kamerového čipu. Databáze dále umožňuje zobrazit výslednou hodnotu nebezpečí poškození sítnice modrým světlem, která se využívá při výpočtu fotobiologické bezpečnosti svítidel dle normy ČSN EN 62471. Kromě výše uvedeného je možné prostřednictvím databáze také doporučit vhodný světelný zdroj pro návrh osvětlovací soustavy pro osvětlování rostlin nebo spolupracovat přímo s projektantem osvětlení a optimalizovat nejlepší kombinaci světelný zdroj – rostlina. Práce obsahuje ucelený postup vyhodnocení, který je pospán v samostatné kapitole, která popisují databázi spektrálních citlivostí a zářivostí. Databáze je otevřená a je možné do ní nahrávat vlastní naměřená data nebo je možné využít řadu měření, které jsou v ní již nahrány. Jedná se o ucelený celek, který má široké spektrum využití.The aim of the presented work is to create a methodology for assessing the influence of spectral radiation of various modern lamps on the observer. The observer in this case can be the human eye, camera system, plant etc. In my work I deal mainly with the evaluation of the influence of spectral radiation of various modern lamps on camera systems and the human eye. The work is intended for a wide range of users who can verify the usability of any lamps or camera chips in practice thanks to this database. The work consists of an open database, which has a versatile use. In the database, after uploading your own data or using the already recorded spectral curves of the radiant intensity of lamps and spectral sensitivities of camera chips, it is possible to display the resulting optimized spectral composition for the selected combination: lamp – light sensor. Furthermore, in the database it is possible to calculate the resulting value of the optimized relative spectral composition between different spectral curves of lamps with different correlated colour temperature and spectral sensitivity of the camera chip. The database also allows you to display the resulting value of the danger of damage to the retina by a blue light, which is used in the calculation of photobiological safety of luminaires according to ČSN EN 62471. In addition to the above, it is also possible to recommend a suitable lamp for the design of a lighting installation for plant lighting through the database or to work directly with the lighting designer and optimize the best combination: lamp – plant. The work contains a comprehensive procedure for evaluating, which is described in a separate chapter, which describe the database of spectral sensitivities and radiances. The database is open and it is possible to upload your own measured data or it is possible to use the series of measurements that are already recorded in it. It is a integrated whole that has a wide range of uses.410 - Katedra elektroenergetikyvyhově

Detectability of dolphins and turtles from Unoccupied Aerial Vehicle (UAV) survey imagery

For many decades occupied aircraft with trained observers have conducted aerial surveys of marine megafauna to estimate population size and dynamics. Recent technological advances mean that unoccupied aerial vehicles (UAVs) now provide a potential alternative to occupied surveys, eliminating some of the disadvantages of occupied surveys such as risk to human life, weather constraints and cost. In this study, data collected from an occupied aircraft (at 500 ft) and a UAV (at 1400 ft) flown at the same time, deployed for counting dugongs, were compared for detecting dolphins and turtles within Shark Bay, Western Australia. The UAV images were manually reviewed post hoc to count the animals sighted and the environmental conditions (visibility, sea state, cloud cover and glare) had been classified by the occupied teams’ data for each image. The UAV captured more sightings (174 dolphins and 368 turtles) than were recorded by the flight team (93 dolphins and 312 turtles). Larger aggregations (>10 animals) were also found in the UAV images (5 aggregations of dolphins and turtles) compared to the occupied teams sightings (0 dolphins and 3 aggregations of turtles). A generalised linear mixed model determined that turtle detection was significantly affected by visibility, while cloud cover, sea state and visibility significantly affected dolphin detection in both platforms. An expert survey of 120 images was also conducted to determine the image ground sampling distance (GSD; four levels from 1.7 to 3.5 cm/pixel) needed to identify dolphin and turtles to species. At 3 cm/pixel only 40% of the dolphins and turtles were identified to species with a reasonable level of certainty (>75% certainty). This study demonstrated that UAVs can be successfully deployed for detecting dolphins and turtles and that a GSD of 1.7 – 3cm/pixel is too low resolution to effectively identify dolphin and turtle species. Overcoming the limitations imposed on UAVs such as aviator regulatory bodies and payload capabilities will make UAVs a pivotal tool for future research, conservation, and management

Seeing the Big Picture: System Architecture Trends in Endoscopy and LED-Based hyperspectral Subsystem Intergration

Early-stage colorectal lesions remain difficult to detect. Early development of neoplasia tends to be small (less than 10 mm) and flat and difficult to distinguish from surrounding mucosa. Additionally, optical diagnosis of neoplasia as benign or malignant is problematic. Low rates of detection of these lesions allow for continued growth in the colorectum and increased risk of cancer formation. Therefore, it is crucial to detect neoplasia and other non-neoplastic lesions to determine risk and guide future treatment. Technology for detection needs to enhance contrast of subtle tissue differences in the colorectum and track multiple biomarkers simultaneously. This work implements one such technology with the potential to achieve the desired multi-contrast outcome for endoscopic screenings: hyperspectral imaging. Traditional endoscopic imaging uses a white light source and a RGB detector to visualize the colorectum using reflected light. Hyperspectral imaging (HSI) acquires an image over a range of individual wavelength bands to create an image hypercube with a wavelength dimension much deeper and more sensitive than that of an RGB image. A hypercube can consist of reflectance or fluorescence (or both) spectra depending on the filtering optics involved. Prior studies using HSI in endoscopy have normally involved ex vivo tissues or xiv optics that created a trade-off between spatial resolution, spectral discrimination and temporal sampling. This dissertation describes the systems design of an alternative HSI endoscopic imaging technology that can provide high spatial resolution, high spectral distinction and video-rate acquisition in vivo. The hyperspectral endoscopic system consists of a novel spectral illumination source for image acquisition dependent on the fluorescence excitation (instead of emission). Therefore, this work represents a novel contribution to the field of endoscopy in combining excitation-scanning hyperspectral imaging and endoscopy. This dissertation describes: 1) systems architecture of the endoscopic system in review of previous iterations and theoretical next-generation options, 2) feasibility testing of a LED-based hyperspectral endoscope system and 3) another LED-based spectral illuminator on a microscope platform to test multi-spectral contrast imaging. The results of the architecture point towards an endoscopic system with more complex imaging and increased computational capabilities. The hyperspectral endoscope platform proved feasibility of a LED-based spectral light source with a multi-furcated solid light guide. Another LED-based design was tested successfully on a microscope platform with a dual mirror array similar to telescope designs. Both feasibility tests emphasized optimization of coupling optics and combining multiple diffuse light sources to a common output. These results should lead to enhanced imagery for endoscopic tissue discrimination and future optical diagnosis for routine colonoscopy