Digital image

Source: Wikipedia, the free encyclopedia.
(Redirected from
Digital image mosaic
)

For broader coverage of this topic, see Digital imaging.

A digital image is an

spatial coordinates denoted with x, y on the x-axis and y-axis, respectively.[1] Depending on whether the image resolution is fixed, it may be of vector or raster type. By itself, the term "digital image" usually refers to raster images or bitmapped images (as opposed to vector images).[citation needed
]

Raster

Main article:
Raster image

Raster images have a finite set of digital values, called picture elements or pixels. 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 or raster map, a two-dimensional array of small integers. These values are often transmitted or stored in a compressed form.

Raster images can be created by a variety of input devices and techniques, such as digital cameras, scanners, 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. The field of digital image processing is the study of algorithms for their transformation.

Raster file formats

Main article:
Raster file format

Most users come into contact with raster images through digital cameras, which use any of several

image file formats
.

Some

Digital Negative (DNG), a proprietary Adobe product described as "the public, archival format for digital camera raw data".[2] Although this format is not yet universally accepted, support for the product is growing, and increasingly professional archivists and conservationists, working for respectable organizations, variously suggest or recommend DNG for archival purposes.[3][4][5][6][7][8][9][10]

Vector

Vector images resulted from mathematical geometry (vector
). In mathematical terms, a vector consists of both a magnitude, or length, and a direction.

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).

Example of vector file types are

AI
.

Image viewing

Image viewer software displayed on images.

W3C
format. In the past, when the Internet was still slow, it was common to provide "preview" images that would load and appear on the website before being replaced by the main image (to give at preliminary impression). Now Internet is fast enough and this preview image is seldom used.

Some scientific images can be very large (for instance, the 46 gigapixel size image of the Milky Way, about 194 Gb in size).[11] Such images are difficult to download and are usually browsed online through more complex web interfaces.

Some viewers offer a

slideshow
utility to display a sequence of images.

History

Further information: Digital imaging § History, and Digital image processing § History
The first scan done by the SEAC in 1957
The SEAC scanner

Early

digital fax machines such as the Bartlane cable picture transmission system
preceded digital cameras and computers by decades. The first picture to be scanned, stored, and recreated in digital pixels was displayed on the Standards Eastern Automatic Computer (
character recognition, and photo enhancement.[13]

Rapid advances in

display technologies, and data compression
algorithms.

The invention of computerized axial tomography (

industry.[14]

Advances in microprocessor technology paved the way for the development and marketing of

photorealism.[15]

Digital image sensors

Main article: Image sensor

The first semiconductor image sensor was the CCD, developed by

television broadcasting.[18]

Early CCD sensors suffered from

digital still cameras. Since then, the PPD has been used in nearly all CCD sensors and then CMOS sensors.[19]

The

MOSFET scaling reaching smaller micron and then sub-micron levels.[21][22] The NMOS APS was fabricated by Tsutomu Nakamura's team at Olympus in 1985.[23] The CMOS active-pixel sensor (CMOS sensor) was later developed by Eric Fossum's team at the NASA Jet Propulsion Laboratory in 1993.[19] By 2007, sales of CMOS sensors had surpassed CCD sensors.[24]

Digital image compression

Main article: Image compression

An important development in digital

Nasir Ahmed in 1972.[25] DCT compression is used in JPEG, which was introduced by the Joint Photographic Experts Group in 1992.[26] JPEG compresses images down to much smaller file sizes, and has become the most widely used image file format on the Internet.[27]

Mosaic

For the artistic concept, see Photographic mosaic.
See also: Image stitching

In digital imaging, a mosaic is a combination of non-overlapping images, arranged in some tessellation. Gigapixel images are an example of such digital image mosaics. Satellite imagery are often mosaicked to cover Earth regions.

Interactive viewing is provided by

virtual-reality photography
.

See also

References

  1. OCLC 966609831
    .
  2. ^ Digital Negative (DNG) Specification Archived 2011-04-20 at the Wayback Machine. San Jose: Adobe, 2005. Vers. 1.1.0.0. p. 9. Accessed on October 10, 2007.
  3. ^ universal photographic digital imaging guidelines (UPDIG): File formats - the raw file issue Archived 2011-10-20 at the Wayback Machine
  4. ^ Archaeology Data Service / Digital Antiquity: Guides to Good Practice - Section 3 Archiving Raster Images - File Formats Archived 2011-12-14 at the Wayback Machine
  5. ^ University of Connecticut: "Raw as Archival Still Image Format: A Consideration" by Michael J. Bennett and F. Barry Wheeler Archived 2011-09-14 at the Wayback Machine
  6. ^ Inter-University Consortium for Political and Social Research: Obsolescence - File Formats and Software Archived 2011-11-02 at the Wayback Machine
  7. ^ JISC Digital Media - Still Images: Choosing a File Format for Digital Still Images - File formats for master archive Archived 2011-11-16 at the Wayback Machine
  8. ^ The J. Paul Getty Museum - Department of Photographs: Rapid Capture Backlog Project - Presentation Archived 2012-06-10 at the Wayback Machine
  9. ^ most important image on the internet - Electronic Media Group: Digital Image File Formats Archived 2010-12-14 at the Wayback Machine
  10. ^ Archives Association of British Columbia: Acquisition and Preservation Strategies (Rosaleen Hill)
  11. ^ "This 46-Gigapixel photo of the Milky Way will blow your mind". 23 October 2015. Archived from the original on 5 July 2018. Retrieved 5 July 2018.
  12. ^ Fiftieth Anniversary of First Digital Image Archived 2010-10-14 at the Wayback Machine.
  13. ^ Azriel Rosenfeld, Picture Processing by Computer, New York: Academic Press, 1969
  14. ^ Gonzalez, Rafael, C; Woods, Richard E (2008). Digital Image Processing, 3rd Edition. Pearson Prentice Hall. p. 577.
    ISBN 978-0-13-168728-8.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  15. ^ Jähne, Bernd (1993). Spatio-temporal image processing, Theory and Scientific Applications. Springer Verlag. p. 208.
    ISBN 3-540-57418-2
    .
  16. ISBN 978-0-8194-3698-6. Archived
    from the original on 2020-11-15. Retrieved 2020-06-06.
  17. ISBN 978-3-319-49088-5. Archived
    from the original on 2020-11-15. Retrieved 2019-10-10.
  18. doi:10.1002/j.1538-7305.1970.tb01790.x
    .
  19. ^
    doi:10.1109/JEDS.2014.2306412
    .
  20. ^ U.S. Patent 4,484,210: Solid-state imaging device having a reduced image lag
  21. S2CID 10556755
    .
  22. S2CID 18831792
    .
  23. S2CID 108450116
    .
  24. ^ "CMOS Image Sensor Sales Stay on Record-Breaking Pace". IC Insights. May 8, 2018. Archived from the original on 21 June 2019. Retrieved 6 October 2019.
  25. doi:10.1016/1051-2004(91)90086-Z. Archived
    from the original on 2016-06-10. Retrieved 2019-09-14.
  26. CCITT. September 1992. Archived
    (PDF) from the original on 30 December 2019. Retrieved 12 July 2019.
  27. BT.com. BT Group. 31 May 2018. Archived from the original
    on 5 August 2019. Retrieved 5 August 2019.
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