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Digital image
 
 
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A digital image is a representation of a two-dimensional image
Image

An image is an artifact, usually two-dimensional , that has a similar appearance to some subject —usually a physical object or a person....
 using ones and zeros (binary). Depending on whether or not the image resolution
Image resolution

Image resolution describes the detail an holds. The term applies equally to digital images, film images, and other types of images. Higher resolution means more image detail....
 is fixed, it may be of vector
Vector graphics

Vector graphics is the use of geometrical Primitive s such as point s, line , curves, and shapes or polygon, which are all based upon mathematical equations, to represent s in computer graphics....
 or raster
Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
 type. Without qualifications, the term "digital image" usually refers to raster images.

aster images have a finite set of digital
Digital

A digital system uses discrete values, usually but not always symbolized numerically to represent information for input, processing, transmission, storage, etc....
 values, called picture elements or pixel
Pixel

In digital imaging, a pixel is the smallest item of information in an image. Pixels are normally arranged in a 2-dimensional grid, and are often represented using dots, squares, or rectangles....
s. The digital image contains a fixed number of rows and columns of pixels.






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A digital image is a representation of a two-dimensional image
Image

An image is an artifact, usually two-dimensional , that has a similar appearance to some subject —usually a physical object or a person....
 using ones and zeros (binary). Depending on whether or not the image resolution
Image resolution

Image resolution describes the detail an holds. The term applies equally to digital images, film images, and other types of images. Higher resolution means more image detail....
 is fixed, it may be of vector
Vector graphics

Vector graphics is the use of geometrical Primitive s such as point s, line , curves, and shapes or polygon, which are all based upon mathematical equations, to represent s in computer graphics....
 or raster
Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
 type. Without qualifications, the term "digital image" usually refers to raster images.

Raster

Raster images have a finite set of digital
Digital

A digital system uses discrete values, usually but not always symbolized numerically to represent information for input, processing, transmission, storage, etc....
 values, called picture elements or pixel
Pixel

In digital imaging, a pixel is the smallest item of information in an image. Pixels are normally arranged in a 2-dimensional grid, and are often represented using dots, squares, or rectangles....
s. The digital image contains a fixed number of rows and columns of pixels. Pixels are the smallest individual element in an image, holding quantized values that represent the brightness of a given color at any specific point.

Typically, the pixels are stored in computer memory as a raster image
Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
 or raster map, a two-dimensional array of small integers. These values are often transmitted or stored in a compressed
Image compression

Image compression is the application of Data compression on digital images. In effect, the objective is to reduce redundancy of the image data in order to be able to store or data transmission data in an efficient form....
 form.

Raster images can be created
Digital imaging

Digital imaging or digital image acquisition is the creation of digital images, typically from a physical object. The term is often assumed to imply or include the digital image processing, , , digital printing, and display of such images....
 by a variety of input devices and techniques, such as digital camera
Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording digital image via an electronics .Many compact digital still cameras can record sound and moving video as well as still photographs....
s, scanner
Image scanner

In computing, a scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass window for scanning....
s, coordinate-measuring machines, seismographic profiling, airborne radar, and more. They can also be synthesized from arbitrary non-image data, such as mathematical functions or three-dimensional geometric models; the latter being a major sub-area of computer graphics
Computer graphics

Computer graphics are graphics created by computers and, more generally, the representation and manipulation of pictorial data by a computer....
. The field of digital image processing
Digital image processing

Digital image processing is the use of computer algorithms to perform on digital images. As a subfield of digital signal processing, 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 si...
 is the study of algorithms for their transformation.

Raster image types

Each pixel of a raster image is typically associated to a specific 'position' in some 2D region, and has a value consisting of one or more quantities (samples) related to that position. Digital images can be classified according to the number and nature of those samples:

  • binary
    Binary image

    A binary image is a digital image that has only two possible values for each pixel. Typically the two colors used for a binary image are black and white though any two colors can be used....
  • grayscale
    Grayscale

    In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample , that is, it carries only intensity information....
  • color
    Color image

    A color image is a digital image that includes color information for each pixel.For visually acceptable results, it is necessary to provide three sample s for each pixel, which are interpreted as coordinates in some color space....
  • false-color
  • multi-spectral
    Multi-spectral image

    Multi-spectral imaging is a technology originally developed for space-based imaging. Multi-spectral imaging can capture light from electromagnetic spectrum, such as infrared....
  • thematic
    Thematic image

    Thematic images are usually image products of Statistical classification processing of multispectral images of the earth surface. The classification process differentiates types of surface such as land, water, forest, lake, structure etc....
  • picture function
    Picture function

    A picture function is a mathematical representation of a two-dimensional image as a Function of two spatial variables. The function f describes the intensity of the point at coordinates ....


The term digital image is also applied to data associated to points scattered over a three-dimensional
Volume

The volume of any solid, liquid, plasma, vacuum or theoretical object is how much three-dimensional space it occupies, often quantified numerically....
 region, such as produced by tomographic
Tomography

Tomography is imaging by sections or sectioning. A device used in tomography is called a tomograph, while the image produced is a tomogram....
 equipment. In that case, each datum is called a voxel
Voxel

A voxel is a volume element, representing a value on a regular grid in 3D computer graphics space. This is analogous to a pixel, which represents 2D computer graphics image data....
.

Raster file formats

Most users come into contact with raster images through digital cameras. Some digital camera
Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording digital image via an electronics .Many compact digital still cameras can record sound and moving video as well as still photographs....
s give access to almost all the data captured by the camera, using the RAW file format. The Universal Photographic Imaging Guidelines (UPDIG) suggests this format be used when possible since RAW files produce the best quality images. This file format allows the photographer and the processing agent the greatest level of control and accuracy for output. Unfortunately, there is an issue of proprietary information [trade secrets] for some camera makers, but organizations are attempting to influence the manufacturers of them to avail these records publicly. An alternative may be a Digital Negative (DNG)
Digital Negative (file format)

In digital photography, the Digital Negative file format is a royalty free RAW image format designed by Adobe Systems. Its specification was announced on September 27, 2004....
 an Adobe product described as “the public, archival format for digital camera raw data”. Although this format is not yet universally accepted, support for the product is growing and archival confidence is building.

Vector

Vector images may be created from scratch with illustration software, or by converting a raster image to vector form.

Often, both raster and vector elements will be combined in one image, for example, in the case of a billboard with text (vector) and photographs (raster).

Image viewing

The user can utilize different program to see the image. The GIF, JPEG
JPEG

In computing, JPEG is a commonly used method of for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality....
 and PNG images can be seen simply using a web browser
Web browser

A Web browser is a application software which enables a user to display and interact with text, images, videos, music, games and other information typically located on a Web page at a website on the World Wide Web or a local area network....
 because they are the standard internet image formats. The SVG
Scalable Vector Graphics

Scalable Vector Graphics is a family of specifications of XML-based file format for describing two-dimensional vector graphics, both static and dynamic ....
 format is more and more used in the web and is a standard W3C format.

Some viewers offer a slideshow
Slideshow

Slideshow is a modern concatenation of "Reversal film Show". A slideshow is a display of a series of chosen images, which is done for artistic or instructional purposes....
 utility, to see the images in a certain folder one after the other automatically.

See also