A digital image is a representation of a two-dimensional image using ones and zeros (binary). An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Image resolution describes the detail an Image holds The term applies equally to Digital images film images and other types of images Vector graphics is the use of geometrical primitives such as points lines, Curves and shapes or Polygon (s which are all based In Computer graphics, a raster graphics image or bitmap, is a Data structure representing a generally rectangular grid of Pixels Without qualifications, the term "digital image" usually refers to raster images.
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Raster
Raster images have a finite set of digital values, called picture elements or pixels. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for In Digital imaging, a pixel ( pict ure el ement is the smallest piece of information in an image 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. In Computer graphics, a raster graphics image or bitmap, is a Data structure representing a generally rectangular grid of Pixels These values are often transmitted or stored in a compressed form. 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
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. Digital imaging or digital image acquisition is the creation of Digital images typically from a physical object Many compact digital still cameras can record Sound and moving Video as well as still Photograph. Historical precedent Scanners can be considered the successors of early telephotography input devices consisting of a rotating drum with a single Photodetector at 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 are Graphics created by Computers and more generally the Representation and Manipulation of Pictorial Data The field of digital image processing is the study of algorithms for their transformation. Digital image processing is the use of computer Algorithms to perform Image processing on Digital images As a subfield of Digital signal processing
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. In Signal processing, sampling is the reduction of a Continuous signal to a Discrete signal. Digital images can be classified according to the number and nature of those samples:
The term digital image is also applied to data associated to points scattered over a three-dimensional region, such as produced by tomographic equipment. A binary image is a Digital image that has only two possible values for each Pixel. In Computing, a grayscale or greyscale Digital image is an image in which the value of each Pixel A (digital color image is a Digital image that includes Color information for each Pixel. A false-color image is an image that depicts a subject in Colors that differ from those a faithful full-color photograph would show Multi-spectral imaging is a technology originally developed for space-based imaging Thematic images are usually image products of classification processing of Multispectral images of the Earth surface A picture function is a mathematical representation of a Two-dimensional image as a function of two spatial variables The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically Tomography is imaging by sections or sectioning A device used in tomography is called a tomograph, while the image produced is a tomogram. In that case, each datum is called a voxel. A voxel (a Portmanteau of the words Volumetric and Pixel) is a volume element representing a value on a Regular grid in
Raster file formats
Most users come into contact with raster images through digital cameras. Some digital cameras give access to almost all the data captured by the camera, using the RAW file format. Many compact digital still cameras can record Sound and moving Video as well as still Photograph. A raw image file contains minimally processed data from the image sensor of a Digital camera or Image scanner. 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) an Adobe product described as “the public, archival format for digital camera raw data”. In Digital photography, the Digital Negative ( DNG) File format is a Royalty free RAW image format designed by Adobe Systems [1] Although this format is not yet universally accepted, support for the product is growing and archival confidence is building. [2]
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 and PNG images can be seen simply using a web browser because they are the standard internet image formats. Portable Network Graphics ( PNG) is a bitmapped image format that employs Lossless data compression. A web browser is a software application which enables a user to display and interact with text images videos music games and other information typically located on a The SVG format is more and more used in the web and is a standard W3C format.
Some viewers offer a slideshow utility, to see the images in a certain folder one after the other automatically.
See also
References
- ^ Digital Negative (DNG) Specification. Image editing encompasses the processes of altering Images whether they be digital photographs traditional analog photographs or Illustrations Digital imaging or digital image acquisition is the creation of Digital images typically from a physical object Digital geometry deals with discrete sets (usually discrete point sets considered to be digitized models or Images of objects of the Digital image processing is the use of computer Algorithms to perform Image processing on Digital images As a subfield of Digital signal processing Digital photography is a form of Photography that utilizes Digital technology to make Digital images of subjects A geocoded photograph is a Photograph which is associated with a geographical location 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 This is a comparison of Image file formats. General Ownership of the format and related information Historical precedent Scanners can be considered the successors of early telephotography input devices consisting of a rotating drum with a single Photodetector at Optical character recognition, usually abbreviated to OCR, is the Mechanical or electronic translation of Images of handwritten typewritten Portable storage devices ( PSD s are small Hard drives designed to copy digital Photographs ( RAW data from cameras A screenshot, screen capture, or screen dump is an Image taken by the Computer to record the visible items displayed on the monitor Signal processing is the analysis interpretation and manipulation of signals Signals of interest include sound, images, biological signals such as Digital Image Correlation and Tracking ( DIC/DDIT) is an optical method that employs tracking & image registration techniques for accurate 2D and 3D measurements of Deformations San Jose: Adobe, 2005. Vers. 1. 1. 0. 0. p. 9. Accessed on October 10, 2007.
- ^ Anderson, Richard. The Universal Photographic Digital Imaging Guidelines. Ed. Michael Stewart. 2006. Vers. 2. 0. UPDIG: Universal Photographic Digital Imaging Guidelines. p. 8. Accessed on October 12, 2007
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