Color CCD Camera Research Articles

Apple fruit size estimation using a 3D machine vision system

Estimation of fruit size in tree fruit crops is essential for selective robotic harvesting and crop-load estimation. Machine vision systems for fruit detection and localization have been studied widely for robotic harvesting and crop-load estimation. However, only a few studies have been carried out to estimate fruit size in orchards using machine vision systems. This study was carried out to develop a machine vision system consisting of a color CCD camera and a time-of-flight (TOF) light-based 3D camera for estimating apple size in tree canopies. As a measure of fruit size, the major axis (longest axis) was estimated based on (i) the 3D coordinates of pixels on corresponding apple surfaces, and (ii) the 2D size of individual pixels within apple surfaces. In the 3D coordinates-based method, the distance between pairs of pixels within apple regions were calculated using 3D coordinates, and the maximum distance between all pixel pairs within an apple region was estimated to be the major axis. The accuracy of estimating the major axis using 3D coordinates was 69.1%. In the pixel-size-based method, the physical sizes of pixels were estimated using a calibration model developed based on pixel coordinates and the distance to pixels from the camera. The major axis length was then estimated by summing the size of individual pixels along the major axis of the fruit. The accuracy of size estimation increased to 84.8% when the pixel size-based method was used. The results showed the potential for estimating fruit size in outdoor environments using a 3D machine vision system.

Brightness measurement of ships navigation at night based on color CCD camera

In order to measure the light environment of the ships navigation at night better, so as to lay the foundation for the evaluation of the light environment of the ships navigation at night and reduce the impact on the safety of the ship's navigation at night, a method of measuring the brightness of the sea light environment by a color CCD camera was proposed. Based on the principle of imaging, the relationship between brightness and camera parameters was deduced and the chromaticity calibration experiment was used to fit the relationship between the three-stimulus value and the standard RGB. The brightness calibration experiment fits out the unknown parameters in the formula and then the brightness measurement formula was determined. The port of Dalian Newport cruise terminal was chosen to verify the measurement formula. The results show that the method can measure the brightness of the light environment of the ships navigation at night, which has high precision.

Spectrally resolved laser interference microscopy

We developed a new quantitative phase microscopy technique, namely, spectrally resolved laser interference microscopy (SR-LIM), with which it is possible to quantify multi-spectral phase information related to biological specimens without color crosstalk using a color CCD camera. It is a single shot technique where sequential switched on/off of red, green, and blue (RGB) wavelength light sources are not required. The method is implemented using a three-wavelength interference microscope and a customized compact grating based imaging spectrometer fitted at the output port. The results of the USAF resolution chart while employing three different light sources, namely, a halogen lamp, light emitting diodes, and lasers, are discussed and compared. The broadband light sources like the halogen lamp and light emitting diodes lead to stretching in the spectrally decomposed images, whereas it is not observed in the case of narrow-band light sources, i.e. lasers. The proposed technique is further successfully employed for single-shot quantitative phase imaging of human red blood cells at three wavelengths simultaneously without color crosstalk. Using the present technique, one can also use a monochrome camera, even though the experiments are performed using multi-color light sources. Finally, SR-LIM is not only limited to RGB wavelengths, it can be further extended to red, near infra-red, and infra-red wavelengths, which are suitable for various biological applications.

High-speed imaging using 3CCD camera and multi-color LED flashes

This paper demonstrates the possibility of capturing full-resolution, high-speed image sequences using a regular 3CCD color camera in conjunction with high-power light emitting diodes of three different colors. This is achieved using a novel approach, referred to as spectral-shuttering, where a high-speed image sequence is captured using short duration light pulses of different colors that are sent consecutively in very close succession. The work presented in this paper demonstrates the feasibility of configuring a high-speed camera system using low cost and readily available off-the-shelf components. This camera can be used for recording six-frame sequences at frame rates up to 20 kHz or three-frame sequences at even higher frame rates. Both color crosstalk and spatial matching between the different channels of the camera are found to be within acceptable limits. A small amount of magnification difference between the different channels is found and a simple calibration procedure for correcting the images is introduced. The images captured using the approach described here are of good quality to be used for obtaining full-field quantitative information using techniques such as digital image correlation and particle image velocimetry. A sequence of six high-speed images of a bubble splash recorded at 400 Hz is presented as a demonstration.

Multi-perspective digital image correlation method using a single color camera

A novel 3D digital image correlation (DIC) system based on a single three charge-couple device (3CCD) color camera is proposed in this paper. Images from three different perspectives are captured by a 3CCD camera using a reflective-based pseudo-vision system. These images are then separated by the different CCD channels, and the correlation algorithm for the multi-camera DIC system is adopted to evaluate the images. Compared to the conventional multi-camera DIC system, the proposed system is much more compact. In addition, the proposed system has no loss of spatial resolution, compares to the traditional single camera DIC system. The complex surface measurement ability and the measurement accuracy is significantly improved through the use of the multi-camera DIC algorithm. The principle of the proposed system is described in detail as well as the experimental setup. A series of validation tests are performed, and the results are verified with the commercial 3D-DIC system.

Design, development and evaluation of an online grading system for peeled pistachios equipped with machine vision technology and support vector machine

In this study, an intelligent system based on combined machine vision (MV) and Support Vector Machine (SVM) was developed for sorting of peeled pistachio kernels and shells. The system was composed of conveyor belt, lighting box, camera, processing unit and sorting unit. A color CCD camera was used to capture images. The images were digitalized by a capture card and transferred to a personal computer for further analysis. Initially, images were converted from RGB color space to HSV color ones. For segmentation of the acquired images, H-component in the HSV color space and Otsu thresholding method were applied. A feature vector containing 30 color features was extracted from the captured images. A feature selection method based onsensitivity analysis was carried out to select superior features. The selected features were presented to SVM classifier. Various SVM models having a different kernel function were developed and tested. The SVM model having cubic polynomial kernel function and 38 support vectors achieved the best accuracy (99.17%) and then was selected to use in online decision-making unit of the system. By launching the online system, it was found that limiting factors of the system capacity were related to the hardware parts of the system (conveyor belt and pneumatic valves used in the sorting unit). The limiting factors led to a distance of 8mm between the samples. The overall accuracy and capacity of the sorter were obtained 94.33% and 22.74kg/h, respectively.

Design and Development of Compact Hand Held Target Acquisition Device

A compact, lightweight hand held target acquisition device, comprising of an infra red imager, colour CCD camera, eye safe laser range finder, global positioning system and digital magnetic compass has been developed. The aim was to develop a compact, lightweight, modular and man-portable multi function electro-optical system with a recognition range of 1 km for vehicles and 500 m for human movement enabling day and night time surveillance, target ranging capability, ability to generate coordinates of the operator and estimation of target coordinates. Hand Held target acquisition device operates on 12 V DC, has integrated signal processing for all the sensors and display electronics with a weight of 3 kg. Overview of the system, design methodology, performance modeling, range simulation of both the IR imager and colour CCD camera and field results have been presented.

Color Stereo-Digital Image Correlation Method Using a Single 3CCD Color Camera

This paper presents a novel color stereo-digital image correlation (stereo-DIC) method using a single 3CCD color camera for full-field shape, motion, and deformation measurements without any sacrifice of the camera sensor spatial resolution. With the aid of a specially designed color separation device using a beam splitter and two optical bandpass filters, images of blue and red colors are simultaneously recorded by the 3CCD camera from two different optical paths. The blue and red channel sub-images extracted from the recorded color images can be analyzed using the regular stereo-DIC algorithm to obtain the full-field three dimensional (3D) information of a test object surface. The effectiveness and accuracy of the proposed technique are demonstrated by a series of real shape, in-plane and out-of-plane translation, and 3D deformation tests.

Single Shot White Light Interference Microscopy for 3D Surface Profilometry Using Single Chip Color Camera

We present a single shot low coherence white light Hilbert phase microscopy (WL-HPM) for quantitative phase imaging of Si opto-electronic devices, i.e., Si integrated circuits (Si-ICs) and Si solar cells. White light interferograms were recorded by a color CCD camera and the interferogram is decomposed into the three colors red, green and blue. Spatial carrier frequency of the WL interferogram was increased sufficiently by means of introducing a tilt in the interferometer. Hilbert transform fringe analysis was used to reconstruct the phase map for red, green and blue colors from the single interferogram. 3D step height map of Si-ICs and Si solar cells was reconstructed at multiple wavelengths from a single interferogram. Experimental results were compared with Atomic Force Microscopy and they were found to be close to each other. The present technique is non-contact, full-field and fast for the determination of surface roughness variation and morphological features of the objects at multiple wavelengths.

Three-Dimensional Continuous Displacement Measurement with Temporal Speckle Pattern Interferometry.

A speckle interferometer which can measure whole field three-dimensional displacements continuously and dynamically has been built. Three different wavelength lasers are used to produce the speckle interferograms of the two in-plane displacements (displacements in the x- and y-direction) and one out-of-plane displacement (displacement in the z-direction), respectively. One color CCD camera is employed to collect these mixed speckle interferograms simultaneously. The mixed interferograms are separated by the Red, Green and Blue channels of the color CCD camera, and then are processed by the wavelet transform technique to extract the phase information of the measured object. The preliminary experiment is carried out to demonstrate the performance of this new device.

Night airglow in RGB mode

To study dynamics of the upper atmosphere, we consider results of the night sky photometry, using a color CCD camera and taking into account the night airglow and features of its spectral composition. We use night airglow observations for 2010–2015, which have been obtained at the ISTP SB RAS Geophysical Observatory (52° N, 103° E) by the camera with KODAK KAI-11002 CCD sensor. We estimate average brightness of the night sky in R, G, B channels of the color camera for eastern Siberia with typical values ranging from ~0.008 to 0.01 erg·cm–2·s–1. Besides, we determine seasonal variations in the night sky luminosities in R, G, B channels of the color camera. In these channels, luminosities decrease in spring, increase in autumn, and have a pronounced summer maximum, which can be explained by scattered light and is associated with the location of the Geophysical Observatory. We consider geophysical phenomena with their optical effects in R, G, B channels of the color camera. For some geophysical phenomena (geomagnetic storms, sudden stratospheric warmings), we demonstrate the possibility of quantitative relationship between enhanced signals in R and G channels and increases in intensities of discrete 557.7 and 630 nm emissions, which are predominant in the airglow spectrum.

Свечение ночной атмосферы в RGB цветовом представлении

TTo study dynamics of the upper atmosphere, we consider results of the night sky photometry, using a color CCD camera and taking into account the night airglow and features of its spectral composition. We use night airglow observations for 2010–2015, which have been obtained at the ISTP SB RAS Geophysical Observatory (52° N, 103° E) by the camera with KODAK KAI-11002 CCD sensor. We estimate average brightness of the night sky in R, G, B channels of the color camera for eastern Siberia with typical values ranging from ~0.008 to 0.01 erg·cm–2·s–1. Besides, we determine seasonal variations in the night sky luminosities in R, G, B channels of the color camera. In these channels, luminosities decrease in spring, increase in autumn, and have a pronounced summer maximum, which can be explained by scattered light and is associated with the location of the Geophysical Observatory. We consider geophysical phenomena with their optical effects in R, G, B channels of the color camera. For some geophysical phenomena (geomagnetic storms, sudden stratospheric warmings), we demonstrate the possibility of quantitative relationship between enhanced signals in R and G channels and increases in intensities of discrete 557.7 and 630 nm emissions, which are predominant in the airglow spectrum.

Fish Injured Rate Measurement Using Color Image Segmentation Method Based on K-Means Clustering Algorithm and Otsu's Threshold Algorithm

This paper proposes two measurement methods for injured rate of fish surface using color image segmentation method based on K-means clustering algorithm and Otsu's threshold algorithm. To do this task, the following steps are done. Firstly, an RGB color image of the fish is obtained by the CCD color camera and then converted from RGB to HSI. Secondly, the S channel is extracted from HSI color space. Thirdly, by applying the K-means clustering algorithm to the HSI color space and applying the Otsu's threshold algorithm to the S channel of HSI color space, the binary images are obtained. Fourthly, morphological processes such as dilation and erosion, etc. are applied to the binary image. Fifthly, to count the number of pixels, the connected-component labeling is adopted and the defined injured rate is gotten by calculating the pixels on the labeled images. Finally, to compare the performances of the proposed two measurement methods based on the K-means clustering algorithm and the Otsu's threshold algorithm, the edge detection of the final binary image after morphological processing is done and matched with the gray image of the original RGB image obtained by CCD camera. The results show that the detected edge of injured part by the K-means clustering algorithm is more close to real injured edge than that by the Otsu' threshold algorithm.

An experimental study of the ignition and combustion characteristics of single droplets of biochar-glycerol-water slurry fuels

The ignition and combustion behaviour of single droplets of biochar-glycerol-water slurry fuels was experimentally investigated. A pine sawdust biochar with a median particle size (D50) of approximately 12µm was used. The slurry fuels with a constant biochar loading of 42wt% and glycerol/water ratios varying from 0 to 0.5 by weight were prepared. A single droplet of a slurry fuel with diameter ranging from 0.5mm to 2.0mm was suspended on a silicon carbide fibre and burned in air at 1023K in an electrically heated tube furnace. The ignition and combustion processes of the droplets were recorded using a colour CCD camera. The ignition delay time, burnout time and burning rate based on the d2 law were determined. It was found that all the slurry fuels exhibited heterogeneous ignition of biochar residue (agglomerate) following water and glycerol evaporation. The addition of glycerol significantly reduced ignition delay time, shortened burnout time and increased burning rate of the droplets. This effect was enhanced with increasing glycerol/water ratio in the slurry fuels. It was also found that the glycerol was not completely evaporated before ignition and the remaining glycerol burned concurrently with the biochar on or near the agglomerate surface. The combustion of agglomerate after ignition was controlled by external oxygen diffusion to the outer layer of the agglomerate under the conditions tested.

Combined Application of Decision Tree and Fuzzy Logic Techniques for Intelligent Grading of Dried Figs

In this study, the quality assessment of dried figs was performed using a machine vision system and data mining techniques. Images from five different classes were obtained using a color CCD camera. After preprocessing and segmentation of the images, 52 features including 6 from size and shape, 4 from texture and 42 from color information were extracted. To find and select the best features for figs grading, the correlation-based feature selection was utilized. It was found that five features (Mouth Area, Homogeneity, Variance value for R, Variance value for B and Kurtosis value for B/R + G+B) surpassed the other features in the attribute selection process. Afterwards, a combined decision tree-fuzzy logic (DT-FL) technique was developed to classify the dried figs based on the superior features. Comparison of validation stage of the utilized DT classifiers indicated that the DT with REP algorithm was the best classifier with an accuracy of 91.74%. Practical Applications Manual grading is a costly and time-consuming method for dried figs grading. Besides, human inspectors' judgment in quality inspection is usually incompatible with each other. Another method for dried figs sorting is mechanical method. This type of product sorting is carried out based on shape properties. It is evident that use of such methods cannot guarantee the precise sorting of figs because the other important quality indices such as decay and defects cannot be controlled. Therefore, utilization of new technologies such as machine vision and artificial intelligence can be a suitable solution for automated inspection of figs. In this study, the quality grading of dried figs was performed using a machine vision system and data mining techniques. Using such a combined classifying model in the form of an automatic sorting system, it is effectively possible to sort different grades of dried figs with high levels of reliability, speed and accuracy.

비 가시 환경에서의 LRF와 CCD 카메라의 성능비교

In this paper, range measurement performance of LRF (Laser Range Finder) module and image contrast of color CCD camera are evaluated under the aerosol (high temperature steam) environments, which are simulated severe accident conditions of the LWR (Light-Water-Reactor) nuclear power plant. Data of LRF and color CCD camera are key informations, which are needed in the implementation of SLAM (Simultaneous Localization and Mapping) function for emergency response robot system to cope with urgently accidents of the nuclear power plant.

Multi-wavelength phase-shifting interferometry for micro-structures measurement based on color image processing in white light interference

Conventional multi-wavelength phase-shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. In this paper, the white light source, with a single-chip CCD color camera, is used to accomplish multi-wavelength phase-shifting interferometry. In addition, we propose an algorithm which combines white light phase-shifting algorithm, equivalent wavelength method and fringe order method to achieve measuring and calibrating the micro-structures ranging from nanometer scale to micrometer scale. Finally, the proposed method is validated by a traceable step height standard.

An experimental investigation into the ignition and combustion characteristics of single droplets of biochar water slurry fuels in air

The ignition and combustion behaviour of single droplets of slurry fuels made from a coconut shell biochar and a pine sawdust biochar was experimentally investigated. The two types of biochar water slurry fuels were prepared with water content varying from 50 to 70wt% and the median size (D50) of the biochar particles being approximately 10μm. Single droplets of the slurry fuels with diameters ranging from 0.5mm to 1.5mm were suspended on a silicon carbide fibre and burned in air at 1023K in an electrically heated tube furnace. The ignition and combustion processes of the droplets of the slurry fuels were recorded using a colour CCD camera at 200fps. The ignition delay time, burnout time and burning rate based on the d2 law were determined. It was found that the ignition delay time slightly increased first and then decreased as the water content increased from 50wt% to 70wt% for the coconut shell biochar slurry fuels and from 60wt% to 70wt% for the pine sawdust biochar slurry fuels, indicating that the effect of water content on the ignition delay time was a trade-off between the water evaporation time and the heating time of residual solid after water evaporation. The combustion of residual solid after ignition followed a shrinking sphere model and was controlled by external oxygen diffusion to the outer surface of the residual solid and a shallow region below the outer surface. The burning rate of the residual solid calculated based on the d2 law ranged from 0.07 to 0.15mm2s−1, which was also independent of the initial droplet size. A slurry fuel with a higher water content showed a slightly greater burning rate as the voids of inter-particles after water evaporation became larger for slurry fuels with higher water contents.

Rapid multispectral endoscopic imaging system for near real-time mapping of the mucosa blood supply in the lung.

We have developed a fast multispectral endoscopic imaging system that is capable of acquiring images in 18 optimized spectral bands spanning 400-760 nm by combining a customized light source with six triple-band filters and a standard color CCD camera. A method is developed to calibrate the spectral response of the CCD camera. Imaging speed of 15 spectral image cubes/second is achieved. A spectral analysis algorithm based on a linear matrix inversion approach is developed and implemented in a graphics processing unit (GPU) to map the mucosa blood supply in the lung in vivo. Clinical measurements on human lung patients are demonstrated.

Focus on lasers and imaging

Focus on lasers and imaging