Computer vision tasks include methods for
acquiring,
processing,
analyzing, and understanding
digital image
A digital image is an image composed of picture elements, also known as pixels, each with '' finite'', '' discrete quantities'' of numeric representation for its intensity or gray level that is an output from its two-dimensional functions f ...
s, and extraction of
high-dimensional data from the real world in order to produce numerical or symbolic information, e.g. in the form of decisions.
"Understanding" in this context signifies the transformation of visual images (the input to the
retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
) into descriptions of the world that make sense to thought processes and can elicit appropriate action. This image understanding can be seen as the disentangling of symbolic information from image data using models constructed with the aid of geometry, physics, statistics, and learning theory.
The
scientific discipline of computer vision is concerned with the theory behind artificial systems that extract information from images. Image data can take many forms, such as video sequences, views from multiple cameras, multi-dimensional data from a
3D scanner, 3D point clouds from
LiDaR
Lidar (, also LIDAR, an acronym of "light detection and ranging" or "laser imaging, detection, and ranging") is a method for determining ranging, ranges by targeting an object or a surface with a laser and measuring the time for the reflected li ...
sensors, or medical scanning devices. The technological discipline of computer vision seeks to apply its theories and models to the construction of computer vision systems.
Subdisciplines of computer vision include
scene reconstruction,
object detection,
event detection,
activity recognition,
video tracking,
object recognition
Object recognition – technology in the field of computer vision for finding and identifying objects in an image or video sequence. Humans recognize a multitude of objects in images with little effort, despite the fact that the image of the ...
,
3D pose estimation, learning, indexing,
motion estimation
In computer vision and image processing, motion estimation is the process of determining ''motion vectors'' that describe the transformation from one 2D image to another; usually from adjacent video frame, frames in a video sequence. It is an wel ...
,
visual servoing,
3D scene modeling, and
image restoration.
Definition
Computer vision is an
interdisciplinary field
Interdisciplinarity or interdisciplinary studies involves the combination of multiple academic disciplines into one activity (e.g., a research project). It draws knowledge from several fields such as sociology, anthropology, psychology, economi ...
that deals with how computers can be made to gain high-level understanding from
digital image
A digital image is an image composed of picture elements, also known as pixels, each with '' finite'', '' discrete quantities'' of numeric representation for its intensity or gray level that is an output from its two-dimensional functions f ...
s or
video
Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...
s. From the perspective of
engineering
Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...
, it seeks to automate tasks that the
human visual system can do.
"Computer vision is concerned with the automatic extraction, analysis, and understanding of useful information from a single image or a sequence of images. It involves the development of a theoretical and algorithmic basis to achieve automatic visual understanding."
[http://www.bmva.org/visionoverview The British Machine Vision Association and Society for Pattern Recognition Retrieved February 20, 2017] As a
scientific discipline, computer vision is concerned with the theory behind artificial systems that extract information from images. The image data can take many forms, such as video sequences, views from multiple cameras, or multi-dimensional data from a
medical scanner. As a technological discipline, computer vision seeks to apply its theories and models for the construction of computer vision systems.
Machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
refers to a systems engineering discipline, especially in the context of factory automation. In more recent times, the terms computer vision and machine vision have converged to a greater degree.
[''Computer Vision'' Principles, algorithms, Applications, Learning 5th Edition by E.R. Davies Academic Press, Elsevier 2018 ISBN 978-0-12-809284-2]
History
In the late 1960s, computer vision began at universities that were pioneering
artificial intelligence
Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of re ...
. It was meant to mimic the
human visual system as a stepping stone to endowing robots with intelligent behavior.
In 1966, it was believed that this could be achieved through an undergraduate summer project, by attaching a camera to a computer and having it "describe what it saw".
What distinguished computer vision from the prevalent field of
digital image processing at that time was a desire to extract
three-dimensional
In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values (''coordinates'') are required to determine the position (geometry), position of a point (geometry), poi ...
structure from images with the goal of achieving full scene understanding. Studies in the 1970s formed the early foundations for many of the computer vision
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...
s that exist today, including
extraction of edges from images, labeling of lines, non-polyhedral and
polyhedral modeling, representation of objects as interconnections of smaller structures,
optical flow, and
motion estimation
In computer vision and image processing, motion estimation is the process of determining ''motion vectors'' that describe the transformation from one 2D image to another; usually from adjacent video frame, frames in a video sequence. It is an wel ...
.
The next decade saw studies based on more rigorous mathematical analysis and quantitative aspects of computer vision. These include the concept of
scale-space, the inference of shape from various cues such as
shading, texture and focus, and
contour models known as snakes. Researchers also realized that many of these mathematical concepts could be treated within the same optimization framework as
regularization and
Markov random fields.
By the 1990s, some of the previous research topics became more active than others. Research in
projective 3-D reconstructions led to better understanding of
camera calibration. With the advent of optimization methods for camera calibration, it was realized that a lot of the ideas were already explored in
bundle adjustment theory from the field of
photogrammetry
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...
. This led to methods for sparse
3-D reconstructions of scenes from multiple images. Progress was made on the dense stereo
correspondence problem and further multi-view stereo techniques. At the same time,
variations of graph cut were used to solve
image segmentation. This decade also marked the first time statistical learning techniques were used in practice to recognize faces in images (see
Eigenface). Toward the end of the 1990s, a significant change came about with the increased interaction between the fields of
computer graphics
Computer graphics deals with generating images and art with the aid of computers. Computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. ...
and computer vision. This included
image-based rendering,
image morphing, view interpolation,
panoramic image stitching and early
light-field rendering.
Recent work has seen the resurgence of
feature
Feature may refer to:
Computing
* Feature recognition, could be a hole, pocket, or notch
* Feature (computer vision), could be an edge, corner or blob
* Feature (machine learning), in statistics: individual measurable properties of the phenome ...
-based methods used in conjunction with machine learning techniques and complex optimization frameworks.
The advancement of
Deep Learning
Deep learning is a subset of machine learning that focuses on utilizing multilayered neural networks to perform tasks such as classification, regression, and representation learning. The field takes inspiration from biological neuroscience a ...
techniques has brought further life to the field of computer vision. The accuracy of deep learning algorithms on several benchmark computer vision data sets for tasks ranging from classification,
segmentation and optical flow has surpassed prior methods.
Related fields
Solid-state physics
Solid-state physics
Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state phy ...
is another field that is closely related to computer vision. Most computer vision systems rely on
image sensors An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of curren ...
, which detect
electromagnetic radiation
In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...
, which is typically in the form of either
visible,
infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
or
ultraviolet light. The sensors are designed using
quantum physics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...
. The process by which light interacts with surfaces is explained using physics. Physics explains the behavior of
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...
which are a core part of most imaging systems. Sophisticated
image sensors An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of curren ...
even require
quantum mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...
to provide a complete understanding of the image formation process.
Also, various measurement problems in physics can be addressed using computer vision, for example, motion in fluids.
Neurobiology
Neurobiology
Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...
has greatly influenced the development of computer vision algorithms. Over the last century, there has been an extensive study of eyes, neurons, and brain structures devoted to the processing of visual stimuli in both humans and various animals. This has led to a coarse yet convoluted description of how natural vision systems operate in order to solve certain vision-related tasks. These results have led to a sub-field within computer vision where artificial systems are designed to mimic the processing and behavior of biological systems at different levels of complexity. Also, some of the learning-based methods developed within computer vision (''e.g.''
neural net and
deep learning
Deep learning is a subset of machine learning that focuses on utilizing multilayered neural networks to perform tasks such as classification, regression, and representation learning. The field takes inspiration from biological neuroscience a ...
based image and feature analysis and classification) have their background in neurobiology. The
Neocognitron, a neural network developed in the 1970s by
Kunihiko Fukushima, is an early example of computer vision taking direct inspiration from neurobiology, specifically the
primary visual cortex
The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus ...
.
Some strands of computer vision research are closely related to the study of
biological vision—indeed, just as many strands of
AI research are closely tied with research into human intelligence and the use of stored knowledge to interpret, integrate, and utilize visual information. The field of biological vision studies and models the physiological processes behind visual perception in humans and other animals. Computer vision, on the other hand, develops and describes the algorithms implemented in software and hardware behind artificial vision systems. An interdisciplinary exchange between biological and computer vision has proven fruitful for both fields.
Signal processing
Yet another field related to computer vision is
signal processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomograph ...
. Many methods for processing one-variable signals, typically temporal signals, can be extended in a natural way to the processing of two-variable signals or multi-variable signals in computer vision. However, because of the specific nature of images, there are many methods developed within computer vision that have no counterpart in the processing of one-variable signals. Together with the multi-dimensionality of the signal, this defines a subfield in signal processing as a part of computer vision.
Robotic navigation
Robot navigation
Robot localization denotes the robot's ability to establish its own position and orientation within the frame of reference. Path planning is effectively an extension of localization, in that it requires the determination of the robot's current pos ...
sometimes deals with autonomous
path planning
Motion planning, also path planning (also known as the navigation problem or the piano mover's problem) is a computational problem to find a sequence of valid configurations that moves the object from the source to destination. The term is used ...
or deliberation for robotic systems to
navigate through an environment. A detailed understanding of these environments is required to navigate through them. Information about the environment could be provided by a computer vision system, acting as a vision sensor and providing high-level information about the environment and the robot
Visual computing
Other fields
Besides the above-mentioned views on computer vision, many of the related research topics can also be studied from a purely mathematical point of view. For example, many methods in computer vision are based on
statistics
Statistics (from German language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a s ...
,
optimization
Mathematical optimization (alternatively spelled ''optimisation'') or mathematical programming is the selection of a best element, with regard to some criteria, from some set of available alternatives. It is generally divided into two subfiel ...
or
geometry
Geometry (; ) is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures. Geometry is, along with arithmetic, one of the oldest branches of mathematics. A mathematician w ...
. Finally, a significant part of the field is devoted to the implementation aspect of computer vision; how existing methods can be realized in various combinations of software and hardware, or how these methods can be modified in order to gain processing speed without losing too much performance. Computer vision is also used in fashion eCommerce, inventory management, patent search, furniture, and the beauty industry.
Distinctions
The fields most closely related to computer vision are
image processing
An image or picture is a visual representation. An image can be two-dimensional, such as a drawing, painting, or photograph, or three-dimensional, such as a carving or sculpture. Images may be displayed through other media, including a pr ...
,
image analysis
Image analysis or imagery analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques. Image analysis tasks can be as simple as reading barcode, bar coded tags or a ...
and
machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
. There is a significant overlap in the range of techniques and applications that these cover. This implies that the basic techniques that are used and developed in these fields are similar, something which can be interpreted as there is only one field with different names. On the other hand, it appears to be necessary for research groups, scientific journals, conferences, and companies to present or market themselves as belonging specifically to one of these fields and, hence, various characterizations which distinguish each of the fields from the others have been presented. In image processing, the input and output are both images, whereas in computer vision, the input is an image or video, and the output could be an enhanced image, an analysis of the image's content, or even a system's behavior based on that analysis.
Computer graphics
Computer graphics deals with generating images and art with the aid of computers. Computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. ...
produces image data from 3D models, and computer vision often produces 3D models from image data.
There is also a trend towards a combination of the two disciplines, ''e.g.'', as explored in
augmented reality
Augmented reality (AR), also known as mixed reality (MR), is a technology that overlays real-time 3D computer graphics, 3D-rendered computer graphics onto a portion of the real world through a display, such as a handheld device or head-mounted ...
.
The following characterizations appear relevant but should not be taken as universally accepted:
*
Image processing
An image or picture is a visual representation. An image can be two-dimensional, such as a drawing, painting, or photograph, or three-dimensional, such as a carving or sculpture. Images may be displayed through other media, including a pr ...
and
image analysis
Image analysis or imagery analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques. Image analysis tasks can be as simple as reading barcode, bar coded tags or a ...
tend to focus on 2D images, how to transform one image to another, ''e.g.'', by pixel-wise operations such as contrast enhancement, local operations such as edge extraction or noise removal, or geometrical transformations such as rotating the image. This characterization implies that image processing/analysis neither requires assumptions nor produces interpretations about the image content.
* Computer vision includes 3D analysis from 2D images. This analyzes the 3D scene projected onto one or several images, ''e.g.'', how to reconstruct structure or other information about the 3D scene from one or several images. Computer vision often relies on more or less complex assumptions about the scene depicted in an image.
*
Machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
is the process of applying a range of technologies and methods to provide imaging-based automatic inspection, process control, and robot guidance
in industrial applications.
Machine vision tends to focus on applications, mainly in manufacturing, ''e.g.'', vision-based robots and systems for vision-based inspection, measurement, or picking (such as
bin picking). This implies that image sensor technologies and control theory often are integrated with the processing of image data to control a robot and that real-time processing is emphasized by means of efficient implementations in hardware and software. It also implies that external conditions such as lighting can be and are often more controlled in machine vision than they are in general computer vision, which can enable the use of different algorithms.
* There is also a field called
imaging
Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image).
Imaging technology is the application of materials and methods to create, preserve, or duplicate images.
...
which primarily focuses on the process of producing images, but sometimes also deals with the processing and analysis of images. For example,
medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
includes substantial work on the analysis of image data in medical applications. Progress in
convolutional neural networks (CNNs) has improved the accurate detection of disease in medical images, particularly in cardiology, pathology, dermatology, and radiology.
* Finally,
pattern recognition
Pattern recognition is the task of assigning a class to an observation based on patterns extracted from data. While similar, pattern recognition (PR) is not to be confused with pattern machines (PM) which may possess PR capabilities but their p ...
is a field that uses various methods to extract information from signals in general, mainly based on statistical approaches and
artificial neural networks. A significant part of this field is devoted to applying these methods to image data.
Photogrammetry
Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...
also overlaps with computer vision, e.g.,
stereophotogrammetry vs.
computer stereo vision.
Applications
Applications range from tasks such as industrial
machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
systems which, say, inspect bottles speeding by on a production line, to research into artificial intelligence and computers or robots that can comprehend the world around them. The computer vision and machine vision fields have significant overlap. Computer vision covers the core technology of automated image analysis which is used in many fields. Machine vision usually refers to a process of combining automated image analysis with other methods and technologies to provide automated inspection and robot guidance in industrial applications. In many computer-vision applications, computers are pre-programmed to solve a particular task, but methods based on learning are now becoming increasingly common. Examples of applications of computer vision include systems for:

* Automatic inspection, ''e.g.'', in manufacturing applications;
* Assisting humans in identification tasks, e.g., a
species identification system;
* Controlling processes, ''e.g.'', an
industrial robot
An industrial robot is a robot system used for manufacturing. Industrial robots are automated, programmable and capable of movement on three or more axes.
Typical applications of robots include robot welding, welding, painting, assembly, Circu ...
;
*
Detecting events, ''e.g.'', for
visual surveillance or
people counting, e.g., in the
restaurant industry;
* Interaction, ''e.g.'', as the input to a device for
computer-human interaction;
* monitoring agricultural crops, e.g. an open-source
vision transformers model has been developed to help farmers automatically detect
strawberry diseases with 98.4% accuracy.
* Modeling objects or environments, ''e.g.'', medical image analysis or
topographical modeling;
* Navigation, ''e.g.'', by an
autonomous vehicle or
mobile robot;
* Organizing information, ''e.g.'', for
indexing databases of images and image sequences.
*Tracking surfaces or planes in 3D coordinates for allowing
Augmented Reality
Augmented reality (AR), also known as mixed reality (MR), is a technology that overlays real-time 3D computer graphics, 3D-rendered computer graphics onto a portion of the real world through a display, such as a handheld device or head-mounted ...
experiences.
*Analyzing the condition of facilities in industry or construction.
*Automatic real-time lip-reading for devices and apps to assist people with disabilities.
For 2024, the leading areas of computer vision were industry (market size US$5.22 billion), medicine (market size US$2.6 billion), military (market size US$996.2 million).
Medicine
One of the most prominent application fields is
medical computer vision, or medical image processing, characterized by the extraction of information from image data to
diagnose a patient. An example of this is the detection of
tumour
A neoplasm () is a type of abnormal and excessive growth of tissue (biology), tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tiss ...
s,
arteriosclerosis or other malign changes, and a variety of dental pathologies; measurements of organ dimensions, blood flow, etc. are another example. It also supports medical research by providing new information: ''e.g.'', about the structure of the brain or the quality of medical treatments. Applications of computer vision in the medical area also include enhancement of images interpreted by humans—
ultrasonic images or
X-ray images, for example—to reduce the influence of noise.
Machine vision
A second application area in computer vision is in industry, sometimes called
machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
, where information is extracted for the purpose of supporting a production process. One example is quality control where details or final products are being automatically inspected in order to find defects. One of the most prevalent fields for such inspection is the
Wafer industry in which every single Wafer is being measured and inspected for inaccuracies or defects to prevent a
computer chip from coming to market in an unusable manner. Another example is a measurement of the position and orientation of details to be picked up by a robot arm. Machine vision is also heavily used in the agricultural processes to remove undesirable foodstuff from bulk material, a process called
optical sorting.
Military
The obvious examples are the detection of enemy soldiers or vehicles and
missile guidance
Missile guidance refers to a variety of methods of guiding a missile or a guided bomb to its intended target. The missile's target accuracy is a critical factor for its effectiveness. Guidance systems improve missile accuracy by improving its P ...
. More advanced systems for missile guidance send the missile to an area rather than a specific target, and target selection is made when the missile reaches the area based on locally acquired image data. Modern military concepts, such as "battlefield awareness", imply that various sensors, including image sensors, provide a rich set of information about a combat scene that can be used to support strategic decisions. In this case, automatic processing of the data is used to reduce complexity and to fuse information from multiple sensors to increase reliability.
Autonomous vehicles
One of the newer application areas is autonomous vehicles, which include
submersible
A submersible is an underwater vehicle which needs to be transported and supported by a larger ship, watercraft or dock, platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent ope ...
s, land-based vehicles (small robots with wheels, cars, or trucks), aerial vehicles, and unmanned aerial vehicles (
UAV). The level of autonomy ranges from fully autonomous (unmanned) vehicles to vehicles where computer-vision-based systems support a driver or a pilot in various situations. Fully autonomous vehicles typically use computer vision for navigation, e.g., for knowing where they are or mapping their environment (
SLAM), for detecting obstacles. It can also be used for detecting certain task-specific events, ''e.g.'', a UAV looking for forest fires. Examples of supporting systems are obstacle warning systems in cars, cameras and LiDAR sensors in vehicles, and systems for autonomous landing of aircraft. Several car manufacturers have demonstrated systems for
autonomous driving of cars. There are ample examples of military autonomous vehicles ranging from advanced missiles to UAVs for recon missions or missile guidance. Space exploration is already being made with autonomous vehicles using computer vision, ''e.g.'',
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
's ''
Curiosity
Curiosity (from Latin , from "careful, diligent, curious", akin to "care") is a quality related to inquisitive thinking, such as exploration, investigation, and learning, evident in humans and other animals. Curiosity helps Developmental psyc ...
'' and
CNSA's ''
Yutu-2'' rover.
Tactile feedback

Materials such as rubber and silicon are being used to create sensors that allow for applications such as detecting microundulations and calibrating robotic hands. Rubber can be used in order to create a mold that can be placed over a finger, inside of this mold would be multiple strain gauges. The finger mold and sensors could then be placed on top of a small sheet of rubber containing an array of rubber pins. A user can then wear the finger mold and trace a surface. A computer can then read the data from the strain gauges and measure if one or more of the pins are being pushed upward. If a pin is being pushed upward then the computer can recognize this as an imperfection in the surface. This sort of technology is useful in order to receive accurate data on imperfections on a very large surface.
Another variation of this finger mold sensor are sensors that contain a camera suspended in silicon. The silicon forms a dome around the outside of the camera and embedded in the silicon are point markers that are equally spaced. These cameras can then be placed on devices such as robotic hands in order to allow the computer to receive highly accurate tactile data.
Other application areas include:
* Support of
visual effects
Visual effects (sometimes abbreviated as VFX) is the process by which imagery is created or manipulated outside the context of
a live-action shot in filmmaking and video production.
The integration of live-action footage and other live-action fo ...
creation for cinema and broadcast, ''e.g.'',
camera tracking (match moving).
*
Surveillance
Surveillance is the monitoring of behavior, many activities, or information for the purpose of information gathering, influencing, managing, or directing. This can include observation from a distance by means of electronic equipment, such as ...
.
*
Driver drowsiness detection
* Tracking and counting organisms in the biological sciences
Typical tasks
Each of the application areas described above employ a range of computer vision tasks; more or less well-defined measurement problems or processing problems, which can be solved using a variety of methods. Some examples of typical computer vision tasks are presented below.
Computer vision tasks include methods for
acquiring,
processing,
analyzing and understanding digital images, and extraction of
high-dimensional data from the real world in order to produce numerical or symbolic information, ''e.g.'', in the forms of decisions.
Understanding in this context means the transformation of visual images (the input of the retina) into descriptions of the world that can interface with other thought processes and elicit appropriate action. This image understanding can be seen as the disentangling of symbolic information from image data using models constructed with the aid of geometry, physics, statistics, and learning theory.
Recognition
The classical problem in computer vision, image processing, and
machine vision
Machine vision is the technology and methods used to provide image, imaging-based automation, automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision ...
is that of determining whether or not the image data contains some specific object, feature, or activity. Different varieties of recognition problem are described in the literature.
*
Object recognition
Object recognition – technology in the field of computer vision for finding and identifying objects in an image or video sequence. Humans recognize a multitude of objects in images with little effort, despite the fact that the image of the ...
(also called object classification)one or several pre-specified or learned objects or object classes can be recognized, usually together with their 2D positions in the image or 3D poses in the scene. Blippar,
Google Goggles
Google Goggles was an image recognition mobile app developed by Google. It was used for searches based on pictures taken by handheld devices. For example, taking a picture of a famous landmark searches for information about it, or taking a pictu ...
, and LikeThat provide stand-alone programs that illustrate this functionality.
* Identificationan individual instance of an object is recognized. Examples include identification of a specific person's face or fingerprint,
identification of handwritten digits, or the identification of a specific vehicle.
*
Detectionthe image data are scanned for specific objects along with their locations. Examples include the detection of an obstacle in the car's field of view and possible abnormal cells or tissues in medical images or the detection of a vehicle in an automatic road toll system. Detection based on relatively simple and fast computations is sometimes used for finding smaller regions of interesting image data which can be further analyzed by more computationally demanding techniques to produce a correct interpretation.
Currently, the best algorithms for such tasks are based on
convolutional neural network
A convolutional neural network (CNN) is a type of feedforward neural network that learns features via filter (or kernel) optimization. This type of deep learning network has been applied to process and make predictions from many different ty ...
s. An illustration of their capabilities is given by the
ImageNet Large Scale Visual Recognition Challenge; this is a benchmark in object classification and detection, with millions of images and 1000 object classes used in the competition.
Performance of convolutional neural networks on the ImageNet tests is now close to that of humans.
The best algorithms still struggle with objects that are small or thin, such as a small ant on the stem of a flower or a person holding a quill in their hand. They also have trouble with images that have been distorted with filters (an increasingly common phenomenon with modern digital cameras). By contrast, those kinds of images rarely trouble humans. Humans, however, tend to have trouble with other issues. For example, they are not good at classifying objects into fine-grained classes, such as the particular breed of dog or species of bird, whereas convolutional neural networks handle this with ease.
Several specialized tasks based on recognition exist, such as:
*
Content-based image retrievalfinding all images in a larger set of images which have a specific content. The content can be specified in different ways, for example in terms of similarity relative to a target image (give me all images similar to image X) by utilizing
reverse image search techniques, or in terms of high-level search criteria given as text input (give me all images which contain many houses, are taken during winter and have no cars in them).
*
Pose estimationestimating the position or orientation of a specific object relative to the camera. An example application for this technique would be assisting a robot arm in retrieving objects from a conveyor belt in an
assembly line
An assembly line, often called ''progressive assembly'', is a manufacturing process where the unfinished product moves in a direct line from workstation to workstation, with parts added in sequence until the final product is completed. By mechan ...
situation or picking parts from a bin.
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Optical character recognition
Optical character recognition or optical character reader (OCR) is the electronics, electronic or machine, mechanical conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, a photo ...
(OCR)identifying
characters in images of printed or handwritten text, usually with a view to encoding the text in a format more amenable to editing or
indexing (''e.g.''
ASCII
ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...
). A related task is reading of 2D codes such as
data matrix and
QR codes.
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Facial recognition a technology that enables the matching of faces in digital images or video frames to a face database, which is now widely used for mobile phone facelock, smart door locking, etc.
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Emotion recognitiona subset of facial recognition, emotion recognition refers to the process of classifying human
emotions. Psychologists caution, however, that internal emotions cannot be reliably detected from faces.
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Shape Recognition Technology (SRT) in
people counter systems differentiating human beings (head and shoulder patterns) from objects.
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Human activity recognition - deals with recognizing the activity from a series of video frames, such as, if the person is picking up an object or walking.
Motion analysis
Several tasks relate to motion estimation, where an image sequence is processed to produce an estimate of the velocity either at each points in the image or in the 3D scene or even of the camera that produces the images. Examples of such tasks are:
*
Egomotiondetermining the 3D rigid motion (rotation and translation) of the camera from an image sequence produced by the camera.
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Trackingfollowing the movements of a (usually) smaller set of interest points or objects (''e.g.'', vehicles, objects, humans or other organisms
) in the image sequence. This has vast industry applications as most high-running machinery can be monitored in this way.
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Optical flowto determine, for each point in the image, how that point is moving relative to the image plane, ''i.e.'', its apparent motion. This motion is a result of both how the corresponding 3D point is moving in the scene and how the camera is moving relative to the scene.
Scene reconstruction
Given one or (typically) more images of a scene, or a video, scene reconstruction aims at
computing a 3D model of the scene. In the simplest case, the model can be a set of 3D points. More sophisticated methods produce a complete 3D surface model. The advent of 3D imaging not requiring motion or scanning, and related processing algorithms is enabling rapid advances in this field. Grid-based 3D sensing can be used to acquire 3D images from multiple angles. Algorithms are now available to stitch multiple 3D images together into point clouds and 3D models.
Image restoration
Image restoration comes into the picture when the original image is degraded or damaged due to some external factors like lens wrong positioning, transmission interference, low lighting or motion blurs, etc., which is referred to as noise. When the images are degraded or damaged, the information to be extracted from them also gets damaged. Therefore, we need to recover or restore the image as it was intended to be. The aim of image restoration is the removal of noise (sensor noise, motion blur, etc.) from images. The simplest possible approach for noise removal is various types of filters, such as low-pass filters or median filters. More sophisticated methods assume a model of how the local image structures look to distinguish them from noise. By first analyzing the image data in terms of the local image structures, such as lines or edges, and then controlling the filtering based on local information from the analysis step, a better level of noise removal is usually obtained compared to the simpler approaches.
An example in this field is
inpainting.
System methods
The organization of a computer vision system is highly application-dependent. Some systems are stand-alone applications that solve a specific measurement or detection problem, while others constitute a sub-system of a larger design which, for example, also contains sub-systems for control of mechanical actuators, planning, information databases, man-machine interfaces, etc. The specific implementation of a computer vision system also depends on whether its functionality is pre-specified or if some part of it can be learned or modified during operation. Many functions are unique to the application. There are, however, typical functions that are found in many computer vision systems.
* Image acquisition – A digital image is produced by one or several
image sensor An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they refraction, pass through or reflection (physics), reflect off objects) into s ...
s, which, besides various types of light-sensitive cameras, include
range sensors, tomography devices, radar, ultra-sonic cameras, etc. Depending on the type of sensor, the resulting image data is an ordinary 2D image, a 3D volume, or an image sequence. The pixel values typically correspond to light intensity in one or several spectral bands (gray images or colour images) but can also be related to various physical measures, such as depth, absorption or reflectance of sonic or electromagnetic waves, or
magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...
.
* Pre-processing – Before a computer vision method can be applied to image data in order to extract some specific piece of information, it is usually necessary to process the data in order to ensure that it satisfies certain assumptions implied by the method. Examples are:
** Re-sampling to ensure that the image coordinate system is correct.
** Noise reduction to ensure that sensor noise does not introduce false information.
** Contrast enhancement to ensure that relevant information can be detected.
**
Scale space representation to enhance image structures at locally appropriate scales.
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Feature extraction
Feature may refer to:
Computing
* Feature recognition, could be a hole, pocket, or notch
* Feature (computer vision), could be an edge, corner or blob
* Feature (machine learning), in statistics: individual measurable properties of the phenome ...
– Image features at various levels of complexity are extracted from the image data.
Typical examples of such features are:
** Lines,
edges and
ridges.
** Localized
interest points such as
corners,
blobs or points.
:More complex features may be related to texture, shape, or motion.
*
Detection/
segmentation – At some point in the processing, a decision is made about which image points or regions of the image are relevant for further processing.
Examples are:
** Selection of a specific set of interest points.
** Segmentation of one or multiple image regions that contain a specific object of interest.
** Segmentation of image into nested scene architecture comprising foreground, object groups, single objects or
salient object parts (also referred to as spatial-taxon scene hierarchy), while the
visual salience is often implemented as
spatial and
temporal attention.
** Segmentation or
co-segmentation of one or multiple videos into a series of per-frame foreground masks while maintaining its temporal semantic continuity.
* High-level processing – At this step, the input is typically a small set of data, for example, a set of points or an image region, which is assumed to contain a specific object.
The remaining processing deals with, for example:
** Verification that the data satisfies model-based and application-specific assumptions.
** Estimation of application-specific parameters, such as object pose or object size.
**
Image recognition – classifying a detected object into different categories.
**
Image registration – comparing and combining two different views of the same object.
* Decision making Making the final decision required for the application,
for example:
** Pass/fail on automatic inspection applications.
** Match/no-match in recognition applications.
** Flag for further human review in medical, military, security and recognition applications.
Image-understanding systems
Image-understanding systems (IUS) include three levels of abstraction as follows: low level includes image primitives such as edges, texture elements, or regions; intermediate level includes boundaries, surfaces and volumes; and high level includes objects, scenes, or events. Many of these requirements are entirely topics for further research.
The representational requirements in the designing of IUS for these levels are: representation of prototypical concepts, concept organization, spatial knowledge, temporal knowledge, scaling, and description by comparison and differentiation.
While inference refers to the process of deriving new, not explicitly represented facts from currently known facts, control refers to the process that selects which of the many inference, search, and matching techniques should be applied at a particular stage of processing. Inference and control requirements for IUS are: search and hypothesis activation, matching and hypothesis testing, generation and use of expectations, change and focus of attention, certainty and strength of belief, inference and goal satisfaction.
Hardware

There are many kinds of computer vision systems; however, all of them contain these basic elements: a power source, at least one image acquisition device (camera, ccd, etc.), a processor, and control and communication cables or some kind of wireless interconnection mechanism. In addition, a practical vision system contains software, as well as a display in order to monitor the system. Vision systems for inner spaces, as most industrial ones, contain an illumination system and may be placed in a controlled environment. Furthermore, a completed system includes many accessories, such as camera supports, cables, and connectors.
Most computer vision systems use visible-light cameras passively viewing a scene at frame rates of at most 60 frames per second (usually far slower).
A few computer vision systems use image-acquisition hardware with active illumination or something other than visible light or both, such as
structured-light 3D scanners,
thermographic camera
Infrared thermography (IRT), thermal video or thermal imaging, is a process where a Thermographic camera, thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are exa ...
s,
hyperspectral imagers,
radar imaging
Radar is a system that uses radio waves to determine the distance (''ranging''), direction (geometry), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to det ...
,
lidar
Lidar (, also LIDAR, an acronym of "light detection and ranging" or "laser imaging, detection, and ranging") is a method for determining ranging, ranges by targeting an object or a surface with a laser and measuring the time for the reflected li ...
scanners,
magnetic resonance images,
side-scan sonar,
synthetic aperture sonar, etc. Such hardware captures "images" that are then processed often using the same computer vision algorithms used to process visible-light images.
While traditional broadcast and consumer video systems operate at a rate of 30 frames per second, advances in
digital signal processing
Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a ...
and
consumer graphics hardware has made high-speed image acquisition, processing, and display possible for real-time systems on the order of hundreds to thousands of frames per second. For applications in robotics, fast, real-time video systems are critically important and often can simplify the processing needed for certain algorithms. When combined with a high-speed projector, fast image acquisition allows 3D measurement and feature tracking to be realized.
Egocentric vision systems are composed of a wearable camera that automatically take pictures from a first-person perspective.
As of 2016,
vision processing units are emerging as a new class of processors to complement CPUs and
graphics processing units (GPUs) in this role.
See also
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Chessboard detection
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Computational imaging
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Computational photography
Computational photography refers to digital image capture and processing techniques that use digital computation instead of optical processes. Computational photography can improve the capabilities of a camera, or introduce features that were no ...
*
Computer audition
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Egocentric vision
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Machine vision glossary
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Space mapping
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Teknomo–Fernandez algorithm
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Vision science
Vision science is the scientific study of visual perception. Researchers in vision science can be called vision scientists, especially if their research spans some of the science's many disciplines.
Vision science encompasses all studies of vision ...
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Visual agnosia
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Visual perception
Visual perception is the ability to detect light and use it to form an image of the surrounding Biophysical environment, environment. Photodetection without image formation is classified as ''light sensing''. In most vertebrates, visual percept ...
*
Visual system
The visual system is the physiological basis of visual perception (the ability to perception, detect and process light). The system detects, phototransduction, transduces and interprets information concerning light within the visible range to ...
Lists
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Outline of computer vision
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List of emerging technologies
This is a list of emerging technologies, which are emerging technologies, in-development technical innovations that have significant potential in their applications. The criteria for this list is that the technology must:
# Exist in some way; ...
*
Outline of artificial intelligence
References
Further reading
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External links
USC Iris computer vision conference list– a complete list of papers of the most relevant computer vision conferences.
Computer Vision Online – news, source code, datasets and job offers related to computer vision
CVonline– Bob Fisher's Compendium of Computer Vision.
British Machine Vision Association– supporting computer vision research within the UK via the BMVC and
MIUA conferences, ''Annals of the
BMVA'' (open-source journal),
BMVA Summer School and one-day meetings
Computer Vision Container, Joe Hoeller GitHub:Widely adopted open-source container for GPU accelerated computer vision applications. Used by researchers, universities, private companies, as well as the U.S. Gov't.
{{Authority control
Image processing
Packaging machinery
Articles containing video clips