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Encyclopedia > Machine vision

Machine vision (MV) is the application of computer vision to industry and manufacturing. Whereas computer vision is mainly focused on machine-based image processing, machine vision most often requires also digital input/output devices and computer networks to control other manufacturing equipment such as robotic arms. Machine Vision is a subfield of engineering that encompasses computer science, optics, mechanical engineering, and industrial automation. One of the most common applications of Machine Vision is the inspection of manufactured goods such as semiconductor chips, automobiles, food and pharmaceuticals. Just as human inspectors working on assembly lines visually inspect parts to judge the quality of workmanship, so machine vision systems use digital cameras, smart cameras and image processing software to perform similar inspections. Computer vision is the science and technology of machines that see. ... Modern car assembly line. ... This article or section does not cite any references or sources. ... A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... UPIICSA IPN - Binary image Image processing is any form of information processing for which the input is an image, such as photographs or frames of video; the output is not necessarily an image, but can be for instance a set of features of the image. ...


Machine vision systems are programmed to perform narrowly defined tasks such as counting objects on a conveyor, reading serial numbers, and searching for surface defects. Manufacturers favour machine vision systems for visual inspections that require high-speed, high-magnification, 24-hour operation, and repeatability of measurements, frequently, these tasks extend roles traditionally occupied by human beings, whose degree of failure is classically high through distraction, illness and circumstance, although humans may display finer perception over the short period and greater flexibility in classification and adaptation to new defects and quality assurance policies. A serial number is a unique number that is one of a series assigned for identification which varies from its successor or predecessor by a fixed discrete integer value. ...


Computers do not 'see' in the same way that human beings are able to. Cameras are not equivalent to human optics and while people can rely on inference systems and assumptions, computing devices must 'see' by examining individual pixels of images, processing them and attempting to develop conclusions with the assistance of knowledge bases and features such as Pattern recognition engines. Although some machine vision algorithms have been developed to mimic human visual perception, a number of unique processing methods have been developed to process images and identify relevant image features in an effective and consistent manner. Machine vision and computer vision systems are capable of processing images consistently, but computer-based image processing systems are typically designed to perform single, repetitive tasks, and despite significant improvements in the field, no machine vision or computer vision system can yet match some capabilities of human vision in terms of image comprehension, tolerance to lighting variations and image degradation, parts' variability etc. Pattern recognition is a field within the area of machine learning. ...

Contents

Components of a machine vision system

A typical machine vision system will consist of several among the following components:

  1. One or more digital or analog camera (black-and-white or colour) with suitable optics for acquiring images
  2. Camera interface for digitizing images (widely known as a "frame grabber")
  3. A processor (often a PC or embedded processor, such as a DSP)
  4. (In some cases, all of the above are combined within a single device, called a smart camera).
  5. Input/Output hardware (e.g. digital I/O) or communication links (e.g. network connection or RS-232) to report results
  6. Lenses to focus the desired field of view onto the image sensor.
  7. Suitable, often very specialized, light sources (LED illuminators, fluorescent or halogen lamps etc.)
  8. A program to process images and detect relevant features.
  9. A synchronizing sensor for part detection (often an optical or magnetic sensor) to trigger image acquisition and processing.
  10. Some form of actuators used to sort or reject defective parts.

The sync sensor determines when a part (often moving on a conveyor) is in position to be inspected. The sensor triggers the camera to take a picture of the part as it passes beneath the camera and often synchronizes a lighting pulse to freeze a sharp image. The lighting used to illuminate the part is designed to highlight features of interest and obscure or minimize the appearance of features that are not of interest (such as shadows or reflections). LED panels of suitable sizes and arrangement are often used to this purpose. This article or section does not cite any references or sources. ... Large format camera lens. ... Digitizing, or digitization, is the process of turning an analog signal into a digital representation of that signal. ... This article needs additional references or sources for verification. ... The term DSP, when used by itself, can refer to: // Underground Bhangra DJ Short for Deathlike Silence Productions. ... A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operates at many speeds for local area networks (LANs). ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... External links LEd Category: TeX ... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ... Distinguish from censure and censer and censor. ... This article is about industrial conveyor belts. ... External links LEd Category: TeX ...


The camera's image is captured by the framegrabber. A framegrabber is a digitizing device (within a smart camera or as a separate computer card) that converts the output of the camera to digital format (typically a two dimensional array of numbers, corresponding to the luminous intensity level of the corresponding point in the field of view, called pixel) and places the image in computer memory so that it may be processed by the machine vision software. Digitizing, or digitization, is the process of turning an analog signal into a digital representation of that signal. ... A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ... This article or section does not cite any references or sources. ...


The software will typically take several steps to process an image. Often the image is first manipulated to reduce noise or to convert many shades of gray to a simple combination of black and white (binarization). Following the initial simplification, the software will count, measure, and/or identify objects, dimensions, defects or other features in the image. As a final step, the software passes or fails the part according to programmed criteria. If a part fails, the software may signal a mechanical device to reject the part; alternately, the system may stop the production line and warn a human worker to fix the problem that caused the failure. A binary image is a digital image that has only two possible values for each pixel. ...


Though most machine vision systems rely on black-and-white cameras, the use of colour cameras is becoming more common. It is also increasingly common for Machine Vision systems to include digital camera equipment for direct connection rather than a camera and separate framegrabber, thus reducing signal degradation. This article or section does not cite any references or sources. ...


"Smart" cameras with built-in embedded processors are capturing an increasing share of the machine vision market. The use of an embedded (and often very optimized) processor eliminates the need for a framegrabber card and external computer, thus reducing cost and complexity of the system while providing dedicated processing power to each camera. Smart cameras are typically less expensive than systems comprising a camera and a board and/or external computer, while the increasing power of embedded processors and DSPs is often providing comparable or higher performance and capabilities than conventional PC-based systems. A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... The term DSP, when used by itself, can refer to: // Underground Bhangra DJ Short for Deathlike Silence Productions. ...


Processing methods

Commercial and open source machine vision software packages typically include a number of different image processing techniques such as the following:

  • Pixel counting: counts the number of light or dark pixels
  • Thresholding: converts an image with gray tones to simply black and white
  • Segmentation: used to locate and/or count parts
    • Blob discovery & manipulation: inspecting an image for discrete blobs of connected pixels (e.g. a black hole in a grey object) as image landmarks. These blobs frequently represent optical targets for machining, robotic capture, or manufacturing failure.
    • Recognition-by-components: extracting geons from visual input
    • Robust pattern recognition: location of an object that may be rotated, partially hidden by another object, or varying in size
  • Barcode reading: decoding of 1D and 2D codes designed to be read or scanned by machines
  • Optical character recognition: automated reading of text such as serial numbers
  • Gauging: measurement of object dimensions in inches or millimeters
  • Edge detection: finding object edges
  • Template matching: finding, matching, and/or counting specific patterns

In most cases, a machine vision system will use a sequential combination of these processing techniques to perform a complete inspection. E.g. A system that reads a barcode may also check a surface for scratches or tampering and measure the length and width of a machined component. This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ... Blob extraction is an image segmentation technique that categorizes the pixels in an image as belonging to one of many discrete regions. ... Geons are simple 3-dimensional forms such as spheres, cubes, cylinders, cones or wedges. ... Pattern recognition is a field within the area of machine learning. ... This article does not cite any references or sources. ... Optical character recognition, usually abbreviated to OCR, is a type of computer software designed to translate images of handwritten or typewritten text (usually captured by a scanner) into machine-editable text, or to translate pictures of characters into a standard encoding scheme representing them (e. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... The goal of edge detection is to mark the points in a digital image at which the luminous intensity changes sharply. ...


Applications of machine vision

The applications of Machine Vision (MV) are diverse, covering areas of endeavour including, but not limited to:

  • Large-scale industrial manufacture
  • Short-run unique object manufacture
  • Safety systems in industrial environments
  • Inspection of pre-manufactured objects (e.g. quality control, failure investigation)
  • Visual stock control and management systems (counting, barcode reading, store interfaces for digital systems)
  • Control of Automated Guided Vehicles (AGVs)
  • Automated monitoring of sites for security and safety
  • Monitoring of agricultural production
  • Quality control and refinement of food products
  • Retail automation
  • Consumer equipment control
  • Medical imaging processes (e.g. Interventional Radiology)
  • Medical remote examination and procedures

Machine vision systems are widely used in semiconductor fabrication; indeed, without machine vision, yields for computer chips would be significantly reduced. Machine vision systems inspect silicon wafers, processor chips, and subcomponents such as resistors and capacitors. NASAs Glenn Research Center cleanroom. ...


In the automotive industry, machine vision systems are used to guide industrial robots, gauge the fit of stamped metal components, and inspect the surface of the painted vehicle for defects. An industrial robot is officially defined by ISO[1] as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes. ...


Though machine vision techniques were developed for the visible spectrum, the same processing techniques may be applied to images captured using imagers sensitive to other forms of spectra such as infrared light or x-ray emissions. Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ...


Related fields

Machine vision is distinct from computer vision. Computer vision extends to topics related to autonomous robotics and machine representation of human vision. Machine Vision refers to automated imaging systems including a wide range of computing disciplines aggregated to form a complete solution to visual problems and can be considered a superset composed of Computer Vision and elements such as equipment control, databasing, network systems, interfacing and machine learning. Computer vision is the science and technology of machines that see. ...


See also

Garry Kasparov playing against Deep Blue, the first machine to win a chess game against a reigning world champion. ... This article does not cite any references or sources. ... Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... Computer vision is the science and technology of machines that see. ... Digital image processing is the use of computer algorithms to perform image processing on digital images. ... First generation Roomba vacuums the carpets in a domestic environment A domestic robot is a robot used for household chores. ... UPIICSA IPN - Binary image Image processing is any form of information processing for which the input is an image, such as photographs or frames of video; the output is not necessarily an image, but can be for instance a set of features of the image. ... An industrial robot is officially defined by ISO[1] as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes. ... Common definitions related to the Machine Vision field. ... A collection of techniques for digital image processing based on mathematical morphology. ... Medical imaging designates the ensemble of techniques and processes used to create images of the human body (or parts thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). ... Optical character recognition, usually abbreviated to OCR, is a type of computer software designed to translate images of handwritten or typewritten text (usually captured by a scanner) into machine-editable text, or to translate pictures of characters into a standard encoding scheme representing them (e. ... Pattern recognition is a field within the area of machine learning. ... Robotic mapping can be used for serving robot guide The problem of Robotic mapping is related to cartography. ... A smart camera is an integrated machine vision system which, in addition to image capture circuitry, includes a processor, which can extract information from images without need for an external processing unit, and interface devices used to make results available to other devices. ... There are very few or no other articles that link to this one. ...

Further reading

E. R. Davies (2004). Machine Vision : Theory, Algorithms, Practicalities. Morgan Kaufmann. 


Batchelor B.G. and Whelan P.F. (1997). Intelligent Vision Systems for Industry. Springer-Verlag. ISBN 3-540-19969-1. . Online PDF version [1]


Demant C., Streicher-Abel B. and Waszkewitz P. (1999). Industrial Image Processing: Visual Quality Control in Manufacturing. Springer-Verlag. ISBN 3-540-66410-6. 


Gonzales R. C. and Wintz P. A. (2001). Digital Image Processing. Longman Higher Education. ISBN 978-0201110265. 


Pham D.T. and Alcock R.J. (2003). Smart Inspection Systems: Techniques and Applications of Intelligent Vision. Academic Press. ISBN 0-12-554157-0. 


Berthold K.P. Horn (1986). Robot Vision. MIT Press. ISBN 0-262-08159-8. 


External links

  • Vision tutorial--Learn what vision is and how it works.
  • The Machine Vision Portal::Buyers Guide::Solutions::News::Informations
  • Informative articles on the specifics of machine vision applications
  • List of smart camera manufacturers

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NERLITE Machine Vision Illumination, Machine Vision Lighting and Machine Vision Imaging Products from Siemens (360 words)
Machine Vision Illumination products, is the industry's most experienced provider of machine vision lighting and machine vision imaging systems.
NERLITE is widely recognized around the globe as the "standard" for machine vision illumination and machine vision imaging.
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Machine vision tends to focus on applications, mainly in industry, e.g., vision based autonomous robots and systems for vision based inspection or measurement.
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