imaging

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imaging

The representation, by means of TV pictures, photographs, graphs, etc., of an object or area by the sensing and recording of patterns of light or other radiation emitted by, reflected from, or transmitted through the object or area. Two broad classifications are chemical imaging, i.e. photography, and electronic imaging. Both are important in astronomy, a variety of photographic emulsions and electronic devices being available for different frequency bands of the electromagnetic spectrum.

The majority of information gathered by ground-based and orbiting telescopes is in digital form so that it can be manipulated by computer. This information can be derived directly from electronic devices, such as CCDs, photon-counting detectors, or photovoltaic detectors, associated with the telescope. These devices respond to radiation by converting it to an electrical signal. They are more sensitive than photographic emulsions, responding to lower levels of intensity and/or producing an image in a shorter time. Photographic plates do, however, provide an image of a much greater area of the sky than existing electronic devices. Machines, such as COSMOS, have therefore been built to measure data on photographic plates rapidly and automatically and produce results in digital form.

An electronic detector can be moved across the focused image of an astronomical object or area of the sky, or the image can be moved across the detector. The electrical signal from the detector is sampled in such a way that an array of values corresponding to an array of portions of the complete image is obtained. Alternatively the image falls on a large number of closely packed detectors, all producing a signal. In each case the result is a set of numbers corresponding to some property of the individual image portions, e.g. the intensity at a particular wavelength. The individual portions into which the image is divided are called pixels (short for picture elements). The greater the number of pixels per image, the higher the resolution, i.e. the greater the detail seen.

This numerical version of the image will normally reside in a computer system, and can be manipulated in different ways in order to highlight different aspects of the original image; the manipulative techniques are known as image processing. The final form of the display can be a TV monitor, a visual display unit attached to a computer, a plotting device, or photographic film, and information derived from the image can also appear in graphs and tables, and be subjected to statistical and numerical analysis.

imaging

[′im·i·jiŋ]
(physics)
The formation of images of objects.

imaging

(graphics)
The production of graphic images, either from a video camera or from digitally generated data (see visualisation), or the recording of such images on microfilm, videotape or laser disk.

See also scanner.

imaging

(1) Creating a film or electronic image of any picture or paper form. Imaging is accomplished by scanning or photographing an object and turning it into a matrix of dots (bitmap), the true meaning of which is unknown to the computer, only to the human viewer. Scanned documents containing text can be encoded into computer data with page recognition software (see OCR). See micrographics, image processing and document imaging.

(2) The illusion of a live performance in audio playback. Microphone placement during recording, post-recording mixing in the studio and the performance of the speakers when listening all contribute to the quality of the imaging. Geared to the type of venue such as a concert hall or nightclub, surround sound processing in the audio equipment creates or enhances effects that attempt to make imaging more realistic.

Speaker Imaging
From the playback side, imaging quality is derived mostly from the speakers. The stiffness and mass of the speaker cone, along with the materials used to suspend the cone in its frame, are the primary criteria that affect the speaker's capability of reproducing sound accurately, and thus the imaging. See surround sound and audiophile.
References in periodicals archive ?
The American College of Physicians (ACP) recommends against screening low-risk, asymptomatic adults with resting ECG, stress ECG, stress echocardiography, or stress myocardial perfusion imaging [152].
Liu, "Evaluation of novel cationic 99mTc(I)-tricarbonyl complexes as potential radiotracers for myocardial perfusion imaging," Nuclear Medicine and Biology, vol.
Marzullo, "Accuracy of myocardial perfusion imaging in detecting multivessel coronary artery disease: A cardiac CZT study," Journal of Nuclear Cardiology, pp.
Technetium 99m based myocardial perfusion imaging predicts clinical outcome in the community outpatient setting: The nuclear utility in the community ('NUC') study.
Increased prognostic value of combined myocardial perfusion imaging and exercise electrocardiography in patients with coronary artery disease.
Of the 444 symptomatic diabetes patients, 78.5% had no inducible ischemia on stress SPECT myocardial perfusion imaging, 16.5% had l%-9% left ventricular ischemia, and 5% had left ventricular ischemia of at least 10%.
Superiority of exercise myocardial perfusion imaging compared with the exercise ECG in the diagnosis of coronary artery disease.
The overall diagnostic accuracy of CT angiography is essentially equivalent to that of SPECT myocardial perfusion imaging, its main competition.
Merhige, clinical associate professor of nuclear medicine at the University at Buffalo (N.Y.) and medical director of The Heart Center at the Niagara Falls Memorial Medical Center, shows that a newer method, called positron emission tomography myocardial perfusion imaging, or PET MPI, provides a more accurate "picture" of coronary obstruction, costs 30% less, reduces the need for follow-up invasive procedures by 50%, and produces excellent clinical outcomes.
CV Therapeutics also has other clinical and preclinical drug development candidates and programs, including regadenoson, which is being developed for potential use as a pharmacologic stress agent in myocardial perfusion imaging studies.

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