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Multiple classifiers for automated classification of defects in sewers
Published in Mark Knight, Neil Thomson, Underground Infrastructure Research, 2020
The basic configuration of the system has been described elsewhere (Moselhi & Shehab-Eldeen, 1999a, b, 2000), and will be briefly described herein for continuity. Figure 1 depicts the overall configuration of the developed automated inspection system. As depicted in Figure 1, the system consists of three main modules. These modules are frame grabber, image analysis and neural network software packages. In utilizing this developed automated inspection system, a CCTV camera first scans the inner surface of a pipe. The videotape that is produced by the CCTV camera is then played back using a VCR. The VCR then feeds the information captured on the tape to the frame grabber module. The frame grabber module captures and digitizes the frames of the acquired images. These digitized images are then fed to the image analysis module. The image analysis module analyzes the digitized images and processes them in a manner so as to prepare a suitable input to the neural network module. The output results obtained from the image analysis module are then fed to several neural networks for training. The trained networks can then be utilized to classify new sets of defects based on their state of knowledge and the extracted features of the respective defects.
Image Processing and Computer Vision for MEMS Testing
Published in Wolfgang Osten, Optical Inspection of Microsystems, 2019
The fundamental tasks of frame grabbers is to provide an electrical interface (analog, digital TTL, RS-422, LVDS, or Camera-Link™) compatible with the camera used, to separate synchronization and image signals (analog, composite video signal), to synchronize image and line synchronization signals where necessary, to digitize video signals from analog cameras if required, and to transmit digital image information to the memory (RAM) of the computer used. Additional functional groups can also be added to frame grabbers. Timers generate clocking, synchronization, trigger, and reset signals for cameras. Multiplexers enable several cameras to be connected. Using look-up tables, the grayscale values of the camera pixels can be mapped onto other grayscale values. Memory modules permit the interim memorizing of images or function as first-in, first-out (FIFO) memories during the transmission of images to the computer’s memory. High-end frame grabbers are also equipped with special signal processors or field-programmable gate arrays (FPGA’s) and program memories, thus enabling image-processing algorithms to be performed extremely fast and without placing a strain on the computer’s processor. A block diagram of the principal component of a frame grabber is shown in Figure 1.22.
Digital Image Processing Systems
Published in Scott E. Umbaugh, Digital Image Processing and Analysis, 2017
A standard analog video camera requires a frame grabber, or image digitizer, to interface with the computer. The frame grabber is a special purpose piece of hardware that accepts a standard analog video signal, and outputs an image in the form that a computer can understand—a digital image. Analog video standards vary throughout the world; RS-170A, RS-330, and RS-343A are the monochrome video standards in the North America and Japan. RS-343A is used for high-resolution video with 675 to 1023 lines per frame. CCIR is the monochrome standard used primarily in Europe. The three color video standards are NTSC, PAL, and SECAM. NTSC is used in North America, Japan, and parts of South America, while PAL is used in parts of Africa, Asia, and Northern Europe. SECAM is used in parts of Africa, Asia, Eastern Europe, Russia, and France. NTSC is 525 lines, 30 frames (60 fields) per second, 2:1 interlaced standard. PAL and SECAM are 625 lines, 25 frames (50 fields) per second, 2:1 interlaced standards.
Comparison of optimisation strategies for the improvement of depth detection capability of Pulse-Compression Thermography
Published in Quantitative InfraRed Thermography Journal, 2020
H. Malekmohammadi, S. Laureti, P. Burrascano, M. Ricci
A National Instrument PCI-6711 Arbitrary Waveform Generator (AWG) board and a National Instrument 1433 Camera Link Frame Grabber were connected to a PC, and an ad hoc virtual instrument developed in LabVIEW managed the signal generation/acquisition. The AWG board provided both the wanted linear chirp excitation and a reference clock signal (CLK) for triggering the IR camera acquisition, which was a Xenics Onca-MWIR-InSb camera placed in reflection mode. A sketch of the experimental set-up used is depicted in Figure 3. The coded signal was input into a TDK Lambda GEN 750W power supply that fed eight LED chips in the visible spectrum placed at about 30 cm from the SUT. The LED chips are capable to provide a maximum overall power of 400 W. The thermograms were acquired at 40 FPS.