Examples of fields that use digital image processing

One of the simplest ways to develop a basic understanding of the extent of image processing applications is to categories images according to their source (e.g., visual, x-ray and son on). The principle energy source for images in use today is the electromagnetic energy spectrum. Other important sources of energy include acoustic, ultrasonic and electronic (in the form of electron beams used in electron microscopy). Synthetic images used for modeling and visualization are generated by computer.
Electromagnetic waves can be conceptualized as propagating sinusoidal waves of varying wavelengths, or they can be thought of as a stream of mass less particles, each traveling in a wavelike pattern and moving at the speed of light. Each mass less particle contain a certain amount (bundle ) of energy. Each bundle of energy is called a photon. If spectral bands are grouped according to energy per photon, we obtain the spectrum ranging from gamma rays (highest energy) at the one end to radio waves (lowest energy) at the other.

Gammaray imaging
Major uses of imaging based on gamma rays include nuclear medicine and astronomical observations. In nuclear medicine, the approach is to inject a patient with a radioactive isotope that emits gamma rays as it decays. Images are produced from emissions collected by gamma ray detectors.
Positron emission tomography(PET)
The patient is given a radioactive isotope that emits positrons as it decays. When a positron meets a electron, both are annihilated and two gamma rays are given off. These are detected and a tomographic image is created using the basic principles of tomography.

X-ray Imaging (oldest source of EM radiation)
X-rays for medical and industrial imaging are generated using an x-ray tube, which is a vacuum tube with a cathode and anode. The cathode is heated, causing free electrons to be released. These electrons flow at high speed to the positively charged anode. When the electron strike a nucleus, energy is released in the form x-ray radiation. The energy(penetrating power) of the x-rays is controlled by a current applied to the filament in the cathode.
Angiography is another major application in an area called contrast enhancement radiography. The procedure is used to obtain images of blodd vessels. A catheter ( a small flexible hollow tube) is inserted, for example into an artery of vein in the groin. The catheter is threaded into the blood vessel and guided to the area to be studied. When the catheter reaches the site under investigation, an x-ray contrast medium is injected through the catheter. This enhances contrast of the blood vessles and enables the radiologist to see any irregularities or blockages.

Imaging in the visible and infrared bands
Infrared band often is used in conjunction with visual imaging. The applications ranges from light microscopy, astronomy, remote sensing industry and law enforcement.
Eg:
Microscopy- the applications ranges from enhancement to measurement
Remote sensing-weather observation from multispectral images from satellites
Industry-check up the bottledrink with less quantity
Law enforcement – biometrics

Imaging in the microwave band
Dominant application in microwave band is radar. The unique feature of imaging radar is its ability to collect data over virtually any region at any time, regardless of weather or ambient lighting conditions. Some radar waves can penetrate clouds and under certain conditions can also see through vegetation, ice and extremely dry sand. In many cases, radar is the only way to explore inaccessible regions of the earth’s surface. An imaging radar works like a flash camera in that it provides it own illumination (microwaves pulses) to illuminate an area on the ground and take a snapshot image.

Imaging in the radio band
Major applications of imaging in the radio band are in medicine and astronomy. In medicine radio waves are used in magnetic resonance imaging (MRI). This techniques places a patient in a powerful magnet and passes radio waves through his or her body in short pulses. Each pulse causes a responding pulse of radio waves to be emitted by patient’s tissues. The location from which theses signals orginate and their strength are determined by a computer which produces a two-dimensional picture of a section of the patient.

Other Imaging Modalities Acoustic images, electron microscopy and synthetic (computer – generated images)
Imaging using sound finds application in geological exploration, industry and medicine. The most important commercial applications of image processing in geology are in mineral and oil exploration.
Ultrasound imaging is used routinely in manufacturing, the best known applications of this technique are in medicine, especially in obsterics, where unborn babies are imaged to determine the health of their development.
Fractals are striking examples of computer-generated images.