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Image analysis is the extraction of meaningful information from images; mainly from digital images by means of digital image processing techniques. Image analysis tasks can be as simple as reading bar coded tags or as sophisticated as identifying a person from their face.
Computers are indispensable for the analysis of large amounts of data, for tasks that require complex computation, or for the extraction of quantitative information. On the other hand, the human visual cortex is an excellent image analysis apparatus, especially for extracting higher-level information, and for many applications — including medicine, security, and remote sensing — human analysts still cannot be replaced by computers. For this reason, many important image analysis tools such as edge detectors and neural networks are inspired by human visual perception models.
Computer image analysis
Computer image analysis largely contains the fields of computer or machine vision, and medical imaging, and makes heavy use of pattern recognition, digital geometry, and signal processing. This field of computer science developed in the 1950s at academic institutions such as the MIT A.I. Lab, originally as a branch of artificial intelligence and robotics.
It is the quantitative or qualitative characterization of two-dimensional (2D) or three-dimensional (3D) digital images. 2D images are, for example, to be analyzed in computer vision, and 3D images in medical imaging. The field was established in the 1950sâ€”1970s, for example with pioneering contributions by Azriel Rosenfeld, Herbert Freeman, Jack E. Bresenham, or King-Sun Fu.
There are many different techniques used in automatically analysing images. Each technique may be useful for a small range of tasks, however there still aren't any known methods of image analysis that are generic enough for wide ranges of tasks, compared to the abilities of a human's image analysing capabilities. Examples of image analysis techniques in different fields include:
- 2D and 3D object recognition,
- image segmentation,
- motion detection e.g. Single particle tracking,
- video tracking,
- optical flow,
- medical scan analysis,
- 3D Pose Estimation,
- automatic number plate recognition.
Digital image analysis
Digital Image Analysis is when a computer or electrical device automatically studies an image to obtain useful information from it. Note that the device is often a computer but may also be an electrical circuit, a digital camera or a mobile phone. The applications of digital image analysis are continuously expanding through all areas of science and industry, including:
- medicine, such as detecting cancer in an MRI scan.
- microscopy, such as counting the germs in a swab.
- remote sensing, such as detecting intruders in a house.
- astronomy, such as calculating the size of a planet.
- materials science, such as determining if a metal weld has cracks.
- machine vision, such as to automatically count items in a factory conveyor belt.
- security, such as detecting a person's eye color or hair color.
- robotics, such as to avoid steering into an obstacle.
- optical character recognition, such as automatic license plate detection.
- assay micro plate reading, such as detecting where a chemical was manufactured.
- metallography, such as determining the mineral content of a rock sample.
Object-based image analysis
Object-Based Image Analysis (OBIA) is a sub-discipline of sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors.
In common with the eyes of other mammals, the human eye's non-image-forming photosensitive ganglion cells in the retina receive the light signals which affect adjustment of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock.
The eye is not properly a sphere, rather it is a fused two-piece unit. The smaller frontal unit, more curved, called the cornea is linked to the larger unit called the sclera. The corneal segment is typically about 8 mm (0.3 in) in radius. The sclera constitutes the remaining five-sixths; its radius is typically about 12 mm. The cornea and sclera are connected by a ring called the limbus. The iris â€“ the color of the eye â€“ and its black center, the pupil, are seen instead of the cornea due to the cornea's transparency. To see inside the eye, an ophthalmoscope is needed, since light is not reflected out. The fundus (area opposite the pupil) shows the characteristic pale optic disk (papilla), where vessels entering the eye pass across and optic nerve fibers depart the globe.
The dimensions differ among adults by only one or two millimeters. The vertical measure, generally less than the horizontal distance, is about 24 mm among adults, at birth about 16â€“17 mm. (about 0.65 inch) The eyeball grows rapidly, increasing to 22.5â€“23 mm (approx. 0.89 in) by the age of three years. From then to age 13, the eye attains its full size. The volume is 6.5 ml (0.4 cu. in.) and the weight is 7.5 g. (0.25 oz.)
The eye is made up of three coats, enclosing three transparent structures. The outermost layer is composed of the cornea and sclera. The middle layer consists of the choroid, ciliary body, and iris. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels, which can be seen in an ophthalmoscope.
Within these coats are the aqueous humor, the vitreous body, and the flexible lens. The aqueous humor is a clear fluid that is contained in two areas: the anterior chamber between the cornea and the iris and exposed area of the lens; and the posterior chamber, behind the iris and the rest. The lens is suspended to the ciliary body by the suspensory ligament (Zonule of Zinn), made up of fine transparent fibers. The vitreous body is a clear jelly that is much larger than the aqueous humor, and is bordered by the sclera, zonule, and lens. They are connected via the pupil.
The retina has a static contrast ratio of around 100:1 (about 6Â½ f-stops). As soon as the eye moves (saccades) it re-adjusts its exposure both chemically and geometrically by adjusting the iris which regulates the size of the pupil. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal chemistry (the Purkinje effect) are mostly complete in thirty minutes. Hence, a dynamic contrast ratio of about 1,000,000:1 (about 20 f-stops) is possible. The process is nonlinear and multifaceted, so an interruption by light merely starts the adaptation process over again. Full adaptation is dependent on good blood flow; thus dark adaptation may be hampered by poor circulation, and vasoconstrictors like alcohol or tobacco.
The eye includes a lens not dissimilar to lenses found in optical instruments such as cameras and the same principles can be applied. The pupil of the human eye is its aperture; the iris is the diaphragm that serves as the aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it can range from 2 mm () in a brightly lit place to 8 mm () in the dark. The latter value decreases slowly with age, older people's eyes sometimes dilate to not more than 5-6mm.
Field of view
The approximate field of view of a human eye is 95Â° out, 75Â° down, 60Â° in, 60Â° up. About 12â€“15Â° temporal and 1.5Â° below the horizontal is the optic nerve or blind spot which is roughly 7.5Â° high and 5.5Â° wide.
Eye irritation has been defined as â€œthe magnitude of any stinging, scratching, burning, or other irritating sensation from the eyeâ€�. It is a common problem experienced by people of all ages. Related eye symptoms and signs of irritation are e.g. discomfort, dryness, excess tearing, itching, grating, sandy sensation, smarting, ocular fatigue, pain, scratchiness, soreness, redness, swollen eyelids, and tiredness, etc. These eye symptoms are reported with intensities from severe to less severe. It has been suggested that these eye symptoms are related to different causal mechanisms.
Several suspected causal factors in our environment have been studied so far. One hypothesis is that indoor air pollution may cause eye and airway irritation. Eye irritation depends somewhat on destabilization of the outer-eye tear film, in which the formation of dry spots results in such ocular discomfort as dryness. Occupational factors are also likely to influence the perception of eye irritation. Some of these are lighting (glare and poor contrast)
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Answers:You might get more response if you go visit a clinic or hospital in person. Few of us here in "Computers & Internet" will have access to pictures of people's arms.
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Answers:He sure didn't patent it on any reptile Perish the thought
Answers:well.... their is no vissual instrument out there that can measure the "electrical" activity of the brain, our 3 most sensitive methods for in vivo imaging is MRI, fMRI, and PET. MRI (magnetic resonance imaging) and fMRI work very similar, by detecting what is known as the BOLD signal. Basically they emasure higher activities of blood flow by picking up the iron in blood and spinning the associated electrons of the water molecules in the area (it gets more technical than that). PET (positron emission tomography) is another method of imaging involving the use of radiotracer chemicals. Basically you are treated with low level radiation molecules which either have a non specific (F18- glucose) or can be specific in order to vissualize a type of tissue or cell density (c11 raclopride for vissualization of dopamine neurons in parkinsons patients). Both techniques are able to make 3D images based on the way photographs are taken. basically the vissual software takes thousands of pictures (really readings from detected material either electron spin energy or PET emissions) which can be constructed to form a 3D image. Electrical activity can only be picked up through probes that are measuring alpha, theta, and gamma frequencies given off by the brain, or by electrophysiology probes (however i am not aware of many human protocols for these instruments). Electrophysiology probes are actually inserted into the brain area of interest where it can pick up a field of electrical potential, but to my knowledge most of this work is done in animals.