Conventional CCD Camera Research Articles

Detecting wet surfaces using near infrared lighting

We propose a system to detect wet surfaces using near infrared LED lighting and a conventional CCD camera. There is a sharp fall in the transmission of light through water for wavelengths longer than 920 nm. By detecting this transition it is possible to robustly detect a film of water lying on a surface. This paper considers surfaces that are impermeable, are not hydrophilic, and are sufficiently reflective (reflectivity, rho>0.4). A system is demonstrated that can detect water on a wide range of surfaces that meet these conditions.

Dual Layer LC Panels for Polarization Control to Display Invisible 2D Code

The authors have researched a support system of the reminiscence and life review activity. This support system consists of an interactive tabletop display and interface system. An invisible code is one of the useful technologies. The invisible codes provide us with an operating environment using a pen-like device. However, this technology is applied to the only paper media. The authors think we want to realize an interaction using the invisible code on an electrical media. We propose a method to display invisible codes using LCD panels and to detect a polarized symbol image with a conventional CCD camera.

多チャネル配信による全方位高精細動画像配信サーバの構築

An omnidirectional vision system is an imaging system that can capture a surrounding image in all directions by using a hyperbolic mirror and a conventional CCD camera. This paper proposes a streaming server that can efficiently transfer movies captured by an omnidirectional vision system over the Internet. The proposed system uses multiple channels to deliver multiple movies synchronously. Through this method, the system enables clients to view different directions of omnidirectional movies and also supports the function of changing the view area during the playback period. Evaluation experiments show that our proposed streaming server can effectively deliver multiple movies via multiple channels. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(11): 41–54, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10375

Polarization Selective Wavelength Tunable Filter

In conventional color CCD cameras, each color pixel consists of different pixels that record the red, green or blue light. However, for special applications such as in astronomy, it is desirable to take pictures at a number of specific wavelengths. In this work, we present the design and fabrication of a liquid crystal wavelength tunable filter which is also able to detect the polarization state of the light. The design consists of a 4-stage Lyot–Öhman filter with an additional liquid crystal cell in front of the filter. By applying the right voltage on the first cell, one can choose the polarization component of the transmitted light.

Abstract 898: Can Angiography With Synchrotron Radiation And A High Sensitivity Receiver Make Lower Doses Of Contrast Medium Possible?

Introduction: Contrast-induced nephropathy (CIN) is a serious complication associated with angiography and interventional angioplasty. Increased doses of contrast medium are a major risk factor of CIN. It was assumed that the occurrence of CIN could be decreased by reducing the dose of contrast medium. We investigated the effects of a new high resolution and high contrast angiographic system on the application of diluted contrast medium. Method: Contrast medium was diluted to 32% (a stock solution), 24%, 16%, 12%, 8%, and 4%. Angiography of the hindlimb in rats using a synchrotron radiation and HARP receiver were performed with each concentration of contrast medium (n=5, respectively). The characteristics of synchrotron radiation are high photon density (10,000 times that of conventional X-rays) and straightness of the beam, which lead to high resolution (26 micrometer/pixel). A HARP Receiver is a high sensitivity image capturing system, which was developed by NHK Sci & Tech Res Lab (Tokyo, Japan). It is about 100 times more sensitive than conventional CCD cameras. Each angiographic image was evaluated by 256 grayscale intensity using graphic software NIH Image. The availability of each image as angiography was determined by the judgment of 5 independent cardiologists respectively. Results: In 256 grayscale, the minimum visible contrast distance for identifying vessels was 10. The value of each image in different concentrations of contrast medium was as follows: 4%: 14+/−12, 8%: 22+/−10, 12%: 23+/−18, 16%: 25+/−11, 24%: 28+/−11, 32%: 40+/−10. Vessels are identified from 4% to 32%. Availability as angiography was confirmed from 8% to 32% by common assent. Conclusions: The angiographic system using synchrotron radiation and a HARP receiver was able to take angiographic images with as low as 8% contrast medium. This may lead to beneficial effects in patients who cannot undergo sufficient angiography and interventional angioplasty due to renal dysfunction.

Dual compasses를 이용한 스프레더의 자세 제어

A spreader pose control system using dual-electric compasses has been implemented by measuring the skew angle of the spreader with dual-electric compasses. In the conventional spreader pose measurement, CCD cameras, laser sensors or tilt sensors are mostly used. However those sensors are not only sensitive to the weather and disturbances but also expensive to build the system. To overcome the shortcomings, an inexpensive and efficient system to control the spreader pose has been implemented using the dual-magnetic compasses. Since the spreader iron-structures are noise sources to the magnetic compass, it is not considered to use the magnetic compass to measure the orientation of the spreader. An algorithm to eliminate the interferences of metal structures to the dual compasses has been developed in this paper. The 10:1 reduction model of a spreader control system is implemented and the control performance is demonstrated to show the effectiveness of the dual-magnetic compasses proposed in this research.

Determining star-image location: A new sub-pixel interpolation technique to process image centroids

We develop a theoretical methodology to estimate the location of star centroids in images recorded by CCD and active pixel sensors. The approach may be generalized to other applications were point-sources must be located with high accuracy. In contrast with other approaches, our technique is suitable for use with non-100% fill ratio sensors. The approach is applied experimentally to two camera systems employing sensors with fill-ratios of approximately 50%. We describe experimental approaches to implement the new paradigm and characterize centroid performance using laboratory targets and against real night-sky images. Applied to a conventional CCD camera, a centroid performance of 11.6 times the raw pixel resolution is achieved. Applied to a camera employing an active-pixel sensor a performance of 12.8 is demonstrated. The approach enables the rapid development of autonomous star-camera systems without the extensive characterizations required to derive polynomic fitting coefficients employed by traditional centroid algorithms.

Automated Crop and Weed Monitoring in Widely Spaced Cereals

An approach is described for automatic assessment of crop and weed area in images of widely spaced (0.25 m) cereal crops, captured from a tractor mounted camera. A form of vegetative index, which is invariant over the range of natural daylight illumination, was computed from the red, green and blue channels of a conventional CCD camera. The transformed image can be segmented into soil and vegetative components using a single fixed threshold. A previously reported algorithm was applied to robustly locate the crop rows. Assessment zones were automatically positioned; for crop growth directly over the crop rows, and for weed growth between the rows. The proportion of crop and weed pixels counted was compared with a manual assessment of area density on the basis of high resolution plan view photographs of the same area; this was performed for views with a range of crop and weed levels. The correlation of the manual and automatic measures was examined, and used to obtain a calibration for the automatic approach. The results of mapping of a small field, at two times, are presented. The results of the automated mapping appear to be consistent with manual assessment.

A ternary barcode detection system with a pattern-adaptable dual threshold

A ternary barcode detection system employing a dual-threshold detection method is proposed to increase detection speed and detection range. This system, providing adaptability to any ternary barcode pattern through the attenuation of an enveloped line of a detected barcode signal and subtraction from the original barcode signal, enables detection over a longer range and also at higher scanning speeds while remaining compact and containing a great amount of information. The system was tested and confirmed to operate at a maximum scanning speed of seven times that of conventional CCD cameras under the practical detection range. It is estimated that a combination of ternary barcodes consisting of nine elements per character will enable the system to express at least 640 characters, over 14 times more than the conventional binary barcode Code39. This system is expected to enable the real-time identification of goods in automated warehouses and production lines.

Least squares algorithm for rapid analysis of Fabry–Perot fringe patterns

Accurate measurement and analysis of Fabry–Perot fringe patterns is essential in many areas of optical metrology. This paper presents a least squares, two dimensional method of interferogram acquisition and fringe analysis, which ensures highly accurate results together with rapid measurement. An experimental implementation is also described, using a conventional CCD camera to image fringes, demonstrating a measurement bandwidth of 25 Hz, and an estimated phase measurement accuracy of δ = ± (5 × 10−4).

Using multispectral imaging to measure temperature profiles and emissivity of large thermionic dispenser cathodes

The authors measured temperature, temperature uniformity, and emissivity of two large thermionic tungsten cathodes. This was necessary because their operating life is strongly affected by nonuniformities in temperature. The cathodes were self-heated 6.5 and 8-in. disks operating in a vacuum at about 1l00 °C. We measured the temperature of the cathodes by a combination of multispectral imaging using a conventional CCD camera and spot pyrometry using three spot pyrometers. We took images at the blue end of the spectrum (0.4 μm) to determine temperature accurate to 3% K. Spot pyrometers at the red end of the spectrum (to 1.8 μm) yielded emissivity with an uncertainty of 15%. We emphasized using data in the blue to determine the temperature and data in the red to determine emissivity. Our analysis displays data so that assumptions in determining temperature and emissivity are transparent. Because we obtained a linear relationship between camera counts and integrated exitance of a blackbody, we concluded that the camera was calibrated correctly.

Microwave radiation and X-ray-induced phenomena in semiconductors

We review experimental results on interaction of microwave and X-rays with various semiconductors that have been obtained at the Semiconductor Physics Institute starting from the pioneering works of J. Požela up to his latest achievements. Special attention is paid to the microwave technique allowing one to estimate the hot electron diffusion coefficient in semiconductors and the bigradient effect, the phenomenon which has been recognized as a discovery in 1977. The application aspects of the above research are furthered in two different approaches: in microwave range, this is done via non-destructive characterization of material homogeneity either by excitation of the helicon waves or by a local excitation of millimetre waves in the tested sample, while in X-ray range this is exposed in the application of inhomogeneous and graded-gap semiconductors to convert the X-rays into optical range thus enabling their detection by conventional CCD cameras.

Infrared imaging of subcutaneous veins

Imaging of subcutaneous veins is important in many applications, such as gaining venous access and vascular surgery. Despite a long history of medical infrared (IR) photography and imaging, this technique is not widely used for this purpose. Here we revisited and explored the capability of near-IR imaging to visualize subcutaneous structures, with a focus on diagnostics of superficial veins. An IR device comprising a head-mounted IR LED array (880 nm), a small conventional CCD camera (Toshiba Ik-mui, Tokyo, Japan), virtual-reality optics, polarizers, filters, and diffusers was used in vivo to obtain images of different subcutaneous structures. The same device was used to estimate the IR image quality as a function of wavelength produced by a tunable xenon lamp-based monochrometer in the range of 500-1,000 nm and continuous-wave Nd:YAG (1.06 microm) and diode (805 nm) lasers. The various modes of optical illumination were compared in vivo. Contrast of the IR images in the reflectance mode was measured in the near-IR spectral range of 650-1,060 nm. Using the LED array, various IR images were obtained in vivo, including images of vein structure in a pigmented, fatty forearm, varicose leg veins, and vascular lesions of the tongue. Imaging in the near-IR range (880-930 nm) provides relatively good contrast of subcutaneous veins, underscoring its value for diagnosis. This technique has the potential for the diagnosis of varicose veins with a diameter of 0.5-2 mm at a depth of 1-3 mm, guidance of venous access, podiatry, phlebotomy, injection sclerotherapy, and control of laser interstitial therapy.

Kidney Glomerulus Observation in Interactive VR Space

This paper presents the system designed to observe kidney glomeruli interactively with conventional CCD cameras and immersive virtual reality (VR) space. First, we captured the X-ray transmitted images and converted them to computer tomogram (CT). Second, the three-dimensional (3D) image was reconstructed using various image processing, binarization, dilation, contraction, labeling and surface rendering. Third, we presented the 3D image on the immersive projection system (IPS) and installed the function of on-line counting of the number of glomeruli. This system provides an observer the immersive environment and enables him to count the kidney glomeruli interactively.

Spectral-reflectance reconstruction in the near-infrared region by use of conventional charge-coupled-device camera measurements.

Our aim is to develop a method for obtaining the reflectance spectra of samples in the near-infrared (NIR) region (800-1,000 nm) by using a small number of measurements performed with a conventional CCD camera (multispectral imaging). We experimentally determined the spectral sensitivity of the CCD camera in the NIR range, used a method based on principal component analysis to reconstruct the spectral reflectance of the samples, and analyzed the number and shape of the filters that need tobe used to apply this method. Finally we obtained the reflectance spectra of a set of 30 spectral curves by numerical simulation. The small amount of errors in the spectral reconstruction shows the potential of this method for reconstructing spectral reflectances in the NIR range.

Particle field digital holographic reconstruction in arbitrary tilted planes

Digital holography is applied to the reconstruction of small particles in a plane whose orientation is arbitrary as specified by the user. The diffraction pattern produced by the particles is directly recorded by a conventional CCD camera. The digital recorded image enables the recovery of particle-images in several parallel planes of the probe volume. Afterwards, an interrogation slice corresponding to a thin layer around a theoretical arbitrary tilted plane is fixed. The pixels whose 3D coordinates belong to this slice are selected and juxtaposed to rebuild the particle images. The feasibility is demonstrated on a fiber tilted with respect to the camera plane. A second example is given on an experimental particle field. These results let us predict future applications such as the characterization of particle fields in planes other than those parallel with the camera plane.

Single-shot sonogram generation for femtosecond laser pulse diagnostics by use of two-photon absorption in a silicon CCD camera

We present an experimental technique capable of single-shot recording of an ultrashort laser pulse sonogram by use of two-photon absorption in a conventional silicon CCD camera. The quadratic spectral phase, introduced into a 100-fs pulse by a grating stretcher, was measured and found to be in good agreement with the analytically calculated value. The nonlinear response of silicon allows sonogram characterization in a wavelength range from 1 to 2 mum .

Using multi-exposure of color fringes to measure the beating motion of a moth

A multi-exposure of color fringes method has been developed to improve the capture speed of a conventional color CCD camera. In the method, four groups of projected fringe patterns encoded with different colors and different directions are stored in one CCD frame. Therefore the capture frequency of the conventional CCD can be improved to 200 Hz. It is available to measure the insect wings with low beating frequency, such as dragonfly, moth, or butterfly, whose beating frequency is about 30–40 Hz. We have used the method to measure the beating motion of a moth successfully.

Holographic recording of fast events on a CCD camera

We report on holographic recording of nanosecond events on a conventional CCD camera. Three frames of an air-discharge event, with resolution of 5.9 ns and frame interval of 12 ns, are recorded in a single CCD frame. Each individual frame is reconstructed by digital filtering of the CCD frame, since successively recorded holograms are centered at different carrier frequencies in the spatial frequency domain.

A vision based navigation system for autonomous aircraft

A machine perception system for aircraft and helicopters using multiple sensor data for state estimation is presented. By combining conventional aircraft sensors like gyros, accelerometers, artificial horizon, aerodynamic measuring devices and GPS with vision data taken by conventional CCD-cameras mounted on a pan and tilt platform, the position of the craft can be determined as well as the relative position to runways and natural landmarks. The vision data of natural landmarks are used to improve position estimates during autonomous missions. A built-in landmark management module decides which landmark should be focused on by the vision system, depending on the distance to the landmark and the aspect conditions. More complex landmarks like runways are modeled with different levels of detail that are activated dependent on range. A supervisor process compares vision data and GPS data to detect mis-tracking of the vision system e.g. due to poor visibility and tries to reinitialize the vision system or to set focus on another landmark available. During landing approach obstacles like trucks and airplanes can be detected on the runway. The system has been tested in real-time within a hardware-in-the-loop simulation. Simulated aircraft measurements corrupted by noise and other characteristic sensor errors have been fed into the machine perception system; the image processing module for relative state estimation was driven by computer generated imagery. Results from real-time simulation runs are given.