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Digital image processing
 
 
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Digital image processing is the use of computer algorithm
Algorithm

In mathematics, computing, linguistics and related subjects, an algorithm is a sequence of finite instructions, often used for calculation and data processing....
s to perform image processing
Image processing

In electrical engineering and computer science, image processing is any form of signal processing for which the input is an , such as photographs or video frame; the output of image processing can be either an image or a set of characteristics or parameters related to the image....
 on digital image
Digital image

A digital image is a representation of a two-dimensional using ones and zeros . Depending on whether or not the is fixed, it may be of vector graphics or raster graphics type....
s. As a subfield of digital signal processing
Digital signal processing

Digital signal processing is concerned with the representation of the signal s by a sequence of numbers or symbols and the processing of these signals....
, digital image processing has many advantages over analog image processing; it allows a much wider range of algorithms to be applied to the input data, and can avoid problems such as the build-up of noise and signal distortion during processing.

History
Many of the techniques of digital image processing, or digital picture processing as it was often called, were developed in the 1960s at the Jet Propulsion Laboratory
Jet Propulsion Laboratory

Jet Propulsion Laboratory is a List of federally funded research and development centers and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, California, United States....
, MIT, Bell Labs
Bell Labs

Bell Laboratories is the research organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company .Bell Laboratories has had its headquarters at Berkeley Heights, New Jersey, and it has research and development facilities throughout the world....
, University of Maryland
University of Maryland, College Park

The University of Maryland, College Park is a public research university located in the city of College Park, Maryland in Prince George's County, Maryland outside Washington, D.C....
, and a few other places, with application to satellite imagery
Satellite imagery

Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites....
, wirephoto standards conversion, medical imaging
Medical physics

File:Gamma knife.jpgMedical physics is the application of physics to medicine. It generally concerns physics as applied to medical imaging and radiotherapy, although a medical physicist may also work in many other areas of healthcare....
, videophone
Videophone

A videophone, also known by the trademarked name Picturephone, is a telephone which is capable of both Sound and video duplex transmission....
, character recognition, and photo enhancement.






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Encyclopedia


Digital image processing is the use of computer algorithm
Algorithm

In mathematics, computing, linguistics and related subjects, an algorithm is a sequence of finite instructions, often used for calculation and data processing....
s to perform image processing
Image processing

In electrical engineering and computer science, image processing is any form of signal processing for which the input is an , such as photographs or video frame; the output of image processing can be either an image or a set of characteristics or parameters related to the image....
 on digital image
Digital image

A digital image is a representation of a two-dimensional using ones and zeros . Depending on whether or not the is fixed, it may be of vector graphics or raster graphics type....
s. As a subfield of digital signal processing
Digital signal processing

Digital signal processing is concerned with the representation of the signal s by a sequence of numbers or symbols and the processing of these signals....
, digital image processing has many advantages over analog image processing; it allows a much wider range of algorithms to be applied to the input data, and can avoid problems such as the build-up of noise and signal distortion during processing.

History


Many of the techniques of digital image processing, or digital picture processing as it was often called, were developed in the 1960s at the Jet Propulsion Laboratory
Jet Propulsion Laboratory

Jet Propulsion Laboratory is a List of federally funded research and development centers and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, California, United States....
, MIT, Bell Labs
Bell Labs

Bell Laboratories is the research organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company .Bell Laboratories has had its headquarters at Berkeley Heights, New Jersey, and it has research and development facilities throughout the world....
, University of Maryland
University of Maryland, College Park

The University of Maryland, College Park is a public research university located in the city of College Park, Maryland in Prince George's County, Maryland outside Washington, D.C....
, and a few other places, with application to satellite imagery
Satellite imagery

Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites....
, wirephoto standards conversion, medical imaging
Medical physics

File:Gamma knife.jpgMedical physics is the application of physics to medicine. It generally concerns physics as applied to medical imaging and radiotherapy, although a medical physicist may also work in many other areas of healthcare....
, videophone
Videophone

A videophone, also known by the trademarked name Picturephone, is a telephone which is capable of both Sound and video duplex transmission....
, character recognition, and photo enhancement. But the cost of processing was fairly high with the computing equipment of that era. In the 1970s, digital image processing proliferated, when cheaper computers and dedicated hardware became available. Images could then be processed in real time, for some dedicated problems such as television standards conversion
Television standards conversion

Television standards conversion is the process of changing one type of TV system to another. The most common is from NTSC to PAL or the other way around....
. As general-purpose computers became faster, they started to take over the role of dedicated hardware for all but the most specialized and compute-intensive operations.

With the fast computers and signal processors available in the 2000s, digital image processing has become the most common form of image processing, and is generally used because it is not only the most versatile method, but also the cheapest.

Tasks


Digital image processing allows the use of much more complex algorithms for image processing, and hence can offer both more sophisticated performance at simple tasks, and the implementation of methods which would be impossible by analog means.

In particular, digital image processing is the only practical technology for:
  • Classification
    Statistical classification

    Statistical classification is a procedure in which individual items are placed into groups based on quantitative information on one or more characteristics inherent in the items and based on a training set of previously labeled items....
  • Feature extraction
    Feature extraction

    In pattern recognition and in , Feature extraction is a special form of dimensionality reduction.When the input data to an algorithm is too large to be processed and it is suspected to be notoriously redundant then the input data will be transformed into a reduced representation set of features ....
  • Pattern recognition
    Pattern recognition

    Pattern recognition is a sub-topic of machine learning. It is "the act of taking in raw data and taking an action based on the Category of the data"....
  • Projection
    Projection

    Projection can be any of:* The display of an image by devices such as:**Movie projector**Video projector**Overhead projector**Slide projector...
  • Multi-scale signal analysis


Some techniques which are used in digital image processing include:
  • Principal components analysis
    Principal components analysis

    Principal component analysis involves a mathematical procedure that transforms a number of possibly correlated variables into a smaller number of uncorrelated variables called principal components....
  • Independent component analysis
    Independent component analysis

    Independent component analysis is a computational method for separating a multivariate signal into additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals....
  • Self-organizing map
    Self-organizing map

    A self-organizing map is a type of artificial neural network that is trained using unsupervised learning to produce a low-dimensional , discretized representation of the input space of the training samples, called a map....
    s
  • Hidden Markov model
    Hidden Markov model

    A hidden Markov model is a statistical model in which the system being modeled is assumed to be a Markov process with unknown parameters; the challenge is to determine the hidden parameters from the observable data....
    s
  • Neural networks


Applications


Digital camera images


Digital cameras generally include dedicated digital image processing chips to convert the raw data from the image sensor into a color-corrected image in a standard image file format. Images from digital cameras often receive further processing to improve their quality, a distinct advantage digital cameras have over film cameras. The digital image processing is typically done by special software programs that can manipulate the images in many ways.

Many digital cameras also enable viewing of histogram
Histogram

In statistics, a histogram is a graphical display of tabulated frequency , shown as bars. It shows what proportion of cases fall into each of several Categorization....
s of images, as an aid for the photographer to better understand the rendered brightness range of each shot.

See also


  • Computer graphics
    Computer graphics

    Computer graphics are graphics created by computers and, more generally, the representation and manipulation of pictorial data by a computer....
  • Computer vision
    Computer vision

    Computer vision is the science and technology of machines that see. As a scientific discipline, computer vision is concerned with the theory for building artificial systems that obtain information from images....
  • Digitizing
    Digitizing

    Digitizing or digitization is representing an Object , , document or a Signal by a discrete set of its points or sample s. The result is called "digital group representation" or, more specifically, a "digital image", for the object, and "digital form", for the signal....
  • Endrov
    Endrov

    is an open-source plugins aimed for image analysis and data processing. Being based on Java , it is portable and can both be run locally and as an applet....
  • GPGPU
    GPGPU

    General-purpose computing on graphics processing units is the technique of using a graphics processing unit, which typically handles computation only for computer graphics, to perform computation in applications traditionally handled by the central processing unit....
  • ImageJ
    ImageJ

    ImageJ is a public domain, Java -based program developed at the National Institutes of Health. ImageJ was designed with an open architecture that provides extensibility via Java plugins and recordable macros....
  • Homomorphic filtering
    Homomorphic filtering

    Homomorphic filtering is a generalized technique for signal and image processing, involving a nonlinear mapping to a different domain in which linear filter techniques are applied, followed by mapping back to the original domain....
  • OpenCV
    OpenCV

    OpenCV is a computer vision library originally developed by Intel Corporation. It is free for commercial and research use under a BSD license. The library is cross-platform, and runs on Microsoft Windows, Mac OS X, Linux, PlayStation Portable, VCRT and other embedded devices....
  • Standard test image
    Standard test image

    A standard test image is a digital image file used across different institutions to test and algorithms. By using the same standard test images, different labs are able to compare results, both visually and quantitatively....
  • Super-resolution
    Super-resolution

    Super-resolution are techniques that in some way enhance the of an imaging system. There are different views as to what is considered an SR-technique: some consider only techniques that break the diffraction-limited of systems, while others also consider techniques that merely break the limit of the digital as SR....


External links

  • (contains a Java applet
    Java applet

    A Java applet is an applet delivered to the users in the form of Java bytecode. Java applets can run in a Web browser using a Java Virtual Machine , or in Sun Microsystems's AppletViewer, a stand-alone tool for testing applets....
    )